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Q.
How important are clean and checks?
A.
All heating and cooling systems should be serviced
every year by a heating and cooling professional.
For
furnaces, your service technician should:
•Check
for leaks, soot, rust, corroded electrical contacts
and frayed wires.
•Perform any necessary cleaning, including the
burner and heat exchanger.
•Inspect the venting system and verify that it
is operating properly.
For heat pumps and air conditioners, your technician
should:
•Inspect
all electrical connections.
•Check the operation of the compressor and outdoor
fan motor.
•Inspect the indoor evaporator coil for cleanliness
and clean if necessary.
•Inspect the furnace or air handler blower assembly
for proper operation and cleanliness.
•Check the refrigerant level in the system.
If the air conditioning or heat pump refrigerant level
is low, a proper leak check should be performed, and
the leak should be repaired or the leaking component
should be replaced.
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Q.
What should an HVAC technician check on my system?
A. All heating and cooling systems
should be serviced every year by a heating and cooling
professional.
For
furnaces, your service technician should:
•Check
for leaks, soot, rust, corroded electrical contacts
and frayed wires.
•Perform any necessary cleaning, including the
burner and heat exchanger.
•Inspect the venting system and verify that it
is operating properly.
For heat pumps and air conditioners, your technician
should:
•Inspect
all electrical connections.
•Check the operation of the compressor and outdoor
fan motor.
•Inspect the indoor evaporator coil for cleanliness
and clean if necessary.
•Inspect the furnace or air handler blower assembly
for proper operation and cleanliness.
•Check the refrigerant level in the system.
If the air conditioning or heat pump refrigerant level
is low, a proper leak check should be performed, and
the leak should be repaired or the leaking component
should be replaced.
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Q. How
often should I change my furnace filter?
A.
Replace
your furnace filter at the start of every heating and
cooling season.
In
environments with high dust or pets, ask your technician
about the option of a high-efficiency air filter or
electronic air cleaner that may need to be replaced
just once a year. They work at least seven times better
than a standard filter at removing dust and other particles.
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Q.
What
to do if the air conditioning won't come on:
A.
1.If
you have no electricity, your air conditioner will not
work. Please call your utility company.
2.If you have a digital thermostat and it is not displaying
a temperature, replace your batteries in the thermostat.
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Furnace
troubleshooting
Q.
What
to do if the furnace won't come on:
A.
1.If
you smell gas, please contact the gas supplier from
your neighbor's phone. Do not light any appliance, touch
any electrical switch or use a phone inside your home.
If you cannot reach the gas supplier, please call 911.
2.If you have no electricity, your furnace will not
work. Please call your utility company.
3.If you have a digital thermostat and it is not displaying
a temperature, replace your batteries in the thermostat.
4.If the furnace is on, but no air is coming through
the vents, call a technician for repair work.
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Q.
What
is SEER?
A.
Buying
a new central air conditioning system is a major investment
- both financially and in your home's comfort. The average
split-system air conditioner will last around 16 years,
so you want to make sure you choose a system that you
will be happy with for a long time. Here are some tips
for choosing a central air conditioning system:
Buy
the highest SEER you can afford. SEER stands for Seasonal
Energy Efficiency Ratio and is a measurement of the
efficiency of your cooling system over the course of
a season. The higher the SEER rating, the higher the
efficiency. Systems purchased to prior to 2006 were
mostly in the 8 to 10 SEER range. In 2006, the minimum
efficiency was raised to 13 SEER. Today, air conditioners
such as the Frigidaire iQ Drive® system can be as
high as 24.5 SEER. A 13-SEER system is 30% more efficient
than a 10-SEER system, and a 24.5 SEER system is 145%
more efficient than a 10-SEER system.
Choose
R-410A refrigerant. Most older systems used a refrigerant
called R-22. In 2010, the new refrigerant standard became
R-410A. R-410A is more environmentally friendly than
past refrigerants because it does not deplete the ozone.
Choosing an R-410A system means you may also have to
replace your line set and your indoor coil, but you
will be getting the maximum efficiency out of your new
system.
Identify
the type of system you currently have. If you have an
outdoor section and an indoor section, you have a "split
system." The split system is the most common type
of system. In the central United States and Canada,
the indoor section is the coil box that sits on top
of your gas or oil furnace. (Many homeowners think this
is part of the furnace when it is actually the indoor
section to the air conditioner.) The furnace blower
is used to distribute cool air throughout the home.
In very hot southern regions, the indoor section is
typically an electric furnace or air handler. This product
has the blower and coil inside a single cabinet. If
you do not have an indoor section, you may have a "packaged"
air conditioner. Packaged units are found in select
regions. The packaged air conditioner contains the blower
and coil components all within the outdoor section and
may even provide gas heat or electric strip heat.
Replace
the entire system, not just the air conditioner. An
air conditioner typically has two components -- the
outdoor section and the indoor section as described
above. It may be tempting to replace only the outdoor
section. But in order for your system to achieve the
efficiency you're paying for, you need to have a matched
system that includes a new indoor coil. Additionally,
old indoor components can adversely impact the performance
of your air conditioner, and your new system warranty
could be canceled if it was not installed with the proper
indoor coil or air handler.
Consider
a heat pump. A heat pump works just like an air conditioner,
cooling you all summer long. But in the fall and early
spring, it can also provide cost-effective electric
heat. Many homeowners are choosing a split-system heat
pump over a split-system air conditioner and then pairing
it with a gas furnace. This dual-fuel system can save
you a lot of money because you heat with electricity
when the weather is mild and with gas when the temperatures
dip below freezing, so you are always using the most
cost-effective fuel source to heat your home. If you
have a packaged system, there are also dual-fuel packaged
systems that combine heat pump and gas heat technology.
Don't
skimp on the install. With a heating and cooling system,
the installation is absolutely critical to performance.
Make sure you hire a certified contractor who is going
to address your ductwork and other home needs in addition
to replacing equipment. A quality installation will
cost more upfront, but it will save you in service and
headaches down the road.
Think
about comfort. Many of the higher-end air conditioners
include extra features that will dramatically improve
your home's comfort. Two-stage systems can run at a
high and low stage, so they are quieter and provide
a better mix of air throughout the home (no hot and
cold spots). Also look for noise reduction features
such as compressor sound blankets and swept-wing fan
blades. Imagine not having to turn up the television
when the air conditioner kicks on.
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Q.
What
is difference between 410A & R-22 refrigerant
?
A. Buying a new central air conditioning
system is a major investment - both financially and
in your home's comfort. The average split-system air
conditioner will last around 16 years, so you want to
make sure you choose a system that you will be happy
with for a long time. Here are some tips for choosing
a central air conditioning system:
Buy
the highest SEER you can afford. SEER stands for Seasonal
Energy Efficiency Ratio and is a measurement of the
efficiency of your cooling system over the course of
a season. The higher the SEER rating, the higher the
efficiency. Systems purchased to prior to 2006 were
mostly in the 8 to 10 SEER range. In 2006, the minimum
efficiency was raised to 13 SEER. Today, air conditioners
such as the Frigidaire iQ Drive® system can be as
high as 24.5 SEER. A 13-SEER system is 30% more efficient
than a 10-SEER system, and a 24.5 SEER system is 145%
more efficient than a 10-SEER system.
Choose
R-410A refrigerant. Most older systems used a refrigerant
called R-22. In 2010, the new refrigerant standard became
R-410A. R-410A is more environmentally friendly than
past refrigerants because it does not deplete the ozone.
Choosing an R-410A system means you may also have to
replace your line set and your indoor coil, but you
will be getting the maximum efficiency out of your new
system.
Identify
the type of system you currently have. If you have an
outdoor section and an indoor section, you have a "split
system." The split system is the most common type
of system. In the central United States and Canada,
the indoor section is the coil box that sits on top
of your gas or oil furnace. (Many homeowners think this
is part of the furnace when it is actually the indoor
section to the air conditioner.) The furnace blower
is used to distribute cool air throughout the home.
In very hot southern regions, the indoor section is
typically an electric furnace or air handler. This product
has the blower and coil inside a single cabinet. If
you do not have an indoor section, you may have a "packaged"
air conditioner. Packaged units are found in select
regions. The packaged air conditioner contains the blower
and coil components all within the outdoor section and
may even provide gas heat or electric strip heat.
Replace
the entire system, not just the air conditioner. An
air conditioner typically has two components -- the
outdoor section and the indoor section as described
above. It may be tempting to replace only the outdoor
section. But in order for your system to achieve the
efficiency you're paying for, you need to have a matched
system that includes a new indoor coil. Additionally,
old indoor components can adversely impact the performance
of your air conditioner, and your new system warranty
could be canceled if it was not installed with the proper
indoor coil or air handler.
Consider
a heat pump. A heat pump works just like an air conditioner,
cooling you all summer long. But in the fall and early
spring, it can also provide cost-effective electric
heat. Many homeowners are choosing a split-system heat
pump over a split-system air conditioner and then pairing
it with a gas furnace. This dual-fuel system can save
you a lot of money because you heat with electricity
when the weather is mild and with gas when the temperatures
dip below freezing, so you are always using the most
cost-effective fuel source to heat your home. If you
have a packaged system, there are also dual-fuel packaged
systems that combine heat pump and gas heat technology.
Don't
skimp on the install. With a heating and cooling system,
the installation is absolutely critical to performance.
Make sure you hire a certified contractor who is going
to address your ductwork and other home needs in addition
to replacing equipment. A quality installation will
cost more upfront, but it will save you in service and
headaches down the road.
Think
about comfort. Many of the higher-end air conditioners
include extra features that will dramatically improve
your home's comfort. Two-stage systems can run at a
high and low stage, so they are quieter and provide
a better mix of air throughout the home (no hot and
cold spots). Also look for noise reduction features
such as compressor sound blankets and swept-wing fan
blades. Imagine not having to turn up the television
when the air conditioner kicks on.
Back
To Top
Q.
What type of air conditioner do
I have?
A.
Identify the type of system you currently have.
If you have an outdoor section and an indoor section,
you have a "split system." The split system
is the most common type of system. In the central United
States and Canada, the indoor section is the coil box
that sits on top of your gas or oil furnace. (Many homeowners
think this is part of the furnace when it is actually
the indoor section to the air conditioner.) The furnace
blower is used to distribute cool air throughout the
home. In very hot southern regions, the indoor section
is typically an electric furnace or air handler. This
product has the blower and coil inside a single cabinet.
If you do not have an indoor section, you may have a
"packaged" air conditioner. Packaged units
are found in select regions. The packaged air conditioner
contains the blower and coil components all within the
outdoor section and may even provide gas heat or electric
strip heat.
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Q.
How
to select the right contractor ?
A.
There are two major influences on getting the best heating
and cooling system to fit your needs:
Know
what to ask the contractor. Because heating or cooling
purchases are infrequent, you may not be aware of the
various product solutions that are available to correct
common indoor comfort problems. If you do not speak
up, the contractor may assume you are not interested
in saving energy, lowering utility costs, or correcting
hot and cold spots in your home. Check out our tips
on what questions to ask.
Select
a skilled contractor. When it comes to central heating
and cooling, product performance and reliability greatly
depend on the contractor's ability to design and install
a system compatible for your home.
Here's
how to make sure you are selecting the right dealer
for your new heating and cooling system. An appropriately
sized system that is also installed correctly is critical
to performance and your happiness.
•Check
to see if the dealer possesses all of the appropriate
licensing for installing HVAC equipment in your state
and local area.
•Review the dealer's listing on the Better Business
Bureau.
•Ask how long they have been in business and if
they offer 24/7 service, financing or accept credit
cards.
•A dealer coming into your home should do more
than just inspect your existing system. Follow the dealer
around to see if he or she is checking air flow, inspecting
the duct system, making note of the windows and the
direction your home faces, etc.
•Be wary of anyone who quotes you a price on the
back of a business card after being in your home for
a few minutes, or even over the phone.
•A knowledgeable dealer that has your best interest
in mind will ask about your experiences in the home
-- how long you have lived there, how long you plan
to stay, if you have pets, allergies, smokers, hot and
cold spots and noise.
•A dealer with the tools to address these problems
will offer viable solutions such as air cleaners, zoning
equipment, programmable thermostats, humidifiers, variable
speed and two-stage technology. If they do not offer
these solutions, they may not be the right dealer for
you.
•It takes more time to complete an installation
when done correctly. Expect to pay more for comprehensive
service, but much less in the long run for your system's
performance and maintenance.
•Typically, manufacturer warranties cover the
replacement of faulty components for a limited time.
Failure due to poor installation is typically not warranted
by manufacturers. Select a dealer who will do a good
job the first time and be around to assist you as needed.
The Air Conditioning Contractors of America (ACCA) suggests
this worksheet to evaluate a potential contractor.
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Q.
What you can expect from your
contractor ?
A.
Here are the things you can expect a qualified heating
and cooling dealer to address when you are purchasing
a new system:
•Selecting
the type of system and equipment (plus operating and
safety controls) that are compatible with the architecture
of your home, fuel availability, fuel costs, the space
available for equipment and duct runs, appearance issues
and project cost.
•Calculating energy savings with a new system.
You may find that investing in a new energy-efficient
system with yield monthly savings greater than money
earned on a CD investment or savings account.
•Performing load or sizing calculations for each
room and the load on the central unit(s). New homes
are better insulated and do not have the same capacity
requirements as older homes. Over-sizing a unit can
contribute to uncomfortable temperatures and inefficient
performance.
•Using the proper industry manual procedures and
manufacturer's data to select, size and place equipment,
supply outlets, ducts and returns.
•Disposing of old equipment.
•Installing to local, state and federal codes
and utility regulations.
•Installing the indoor and outdoor equipment.
A split system is the most common installation.
•Installing the refrigerant lines.
•Installing supply air outlets and returns if
they do not exist or are inadequate.
•Installing duct runs (must be sealed and insulated
to R-6 or R-8 if in unconditioned space) if they do
not exist or are inadequate.
•Installing control system(s), such as thermostats
and/or zoning controls.
•Installing furnace gas piping and vent (if applicable).
•Charging the refrigerant system.
•Checking all control cycles.
•Checking refrigerant charge.
•Checking all power supplies, connections, fuel
trains and vents.
•Measuring and adjusting air flow at the unit
and at the rooms (balancing work).
•Educating the homeowner about the system and
equipment (provide all instructions and manufacturer's
documents, including warranties).
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Here
are some common heating and cooling terms and their
definitions. Getting up to speed on industry terms will
help you better understand your dealer’s proposal.
AFUE:
Annual Fuel Utilization Efficiency. The AFUE percentage
tells you how much energy is being converted to heat.
The higher the number, the greater the efficiency.
Air
Handler: The portion of your heating
and cooling system that forces air through your home's
ductwork.
BTU:
British Thermal Units. The amount of heat it takes to
raise one pound of water one degree Fahrenheit. The
higher the BTU rating, the larger the heating capacity
of the furnace or air conditioner.
Capacity:
The ability of a heating or cooling system to heat or
cool a given amount of space. Heating is usually expressed
in BTUs; cooling is expressed in tons.
Certified
matched system: The Air Conditioning,
Heating and Refrigeration Institute (AHRI) puts heating
and cooling equipment through rigorous certification
processes to ensure systems deliver the promised performance
at certain test conditions.
Compressor:
The motor/pump that drives the air conditioning unit.
It is responsible for pumping refrigerant throughout
the system.
Condenser
Coil: Part of the outdoor portion of
a heating or cooling system, which releases or collects
heat from the outside air.
Damper:
A valve or moveable plate used in ductwork that opens
and closes to control airflow. They are used to direct
air to specific areas of the home.
Downflow:
A type of furnace that takes cool air from the top and
blows warm air to the bottom.
Ductwork:
Hollow metal pipes used to transfer air throughout your
house.
ecoLogic:
Frigidaire’s designation of green heating and
cooling equipment. Learn More About ecoLogic.
Electronic
Air Cleaner: An electronic device that
filters out particles and contaminants in indoor air.
Evaporator
Coil: Part of the heating or cooling
system located indoors that cools and dehumidifies the
air by converting liquid refrigerant into gas.
Heat
Exchanger: The major part of the furnace
that transfers heat into your home.
Heat
Pump: A unit that handles both heating
and cooling. In some climates, a heat pump may handle
your heating and cooling needs more efficiently than
a furnace and air conditioner.
Horizontal
Flow: A type of furnace, installed on
its side, which draws air from one side, heats the air
and then sends it out the other side.
HSPF:
Heating Seasonal Performance Factor. Measures the heating
efficiency of a heat pump. The higher the number, the
more efficient the heat pump heats your home.
Humidifier:
A piece of equipment that adds moisture to the air as
it comes out of the furnace.
HVAC:
Heating, Ventilation, and Air Conditioning.
Refrigerant:
A chemical that cools air as it evaporates.
SEER:
Seasonal Energy Efficiency Ratio. SEER measures a unit's
cooling efficiency. The higher the number, the greater
the efficiency.
Single
Package: An outdoor unit that contains
both a heating and a cooling system.
Split
System: Refers to an air conditioner
or heat pump that is combined with indoor components,
such as an evaporator coil inside and a condenser coil
outside your home.
Thermostat:
A device that monitors and controls your temperature
inside your home.
Ton
(of air conditioning): A ton of air conditioning refers
to capacity in relation to melting one ton of ice in
24 hours. The capacity is measured in British Thermal
Units (Btu); 288,000 Btu are required to melt one ton
of ice in 24 hours (or 12,000 Btu/hr). A 2-ton air conditioner
has a nominal capacity of about 24,000 Btu/h.
Upflow:
A type of furnace that draws cool air from the bottom
and blows the warmed air out the top.
Ventilator:
A ventilator captures heating or cooling energy from
stale indoor air and transfers it to fresh incoming
air.
Zone:
Zoning allows you to control the heating and cooling
delivered to specific areas of your house for a custom
solution. Zoning can increase efficiency and comfort
in the area of the house you use most often.
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Q.
How to choose the right HVAC system
A.
There are two major influences on getting the best
system to fit your needs:
Select
a skilled contractor. When it comes to central heating
and cooling, product performance and reliability greatly
depend on the contractor's ability to design and install
a system compatible for your home. Check out our tips
on how to select the right contractor.
Have
an idea of what you want. Because heating or cooling
purchases are infrequent, you may not be aware of the
various product solutions that are available to correct
common indoor comfort problems. If you do not speak
up, the contractor may assume you are not interested
in saving energy, lowering utility costs, correcting
hot and cold spots in your home or a host of other solutions.
The
best way to purchase a system you will be most satisfied
with is to identify all the things that you would like
to improve on from your current system. Some contractors
will ask you these questions, but some may not. Therefore,
educate yourself what you want your system to do for
you.
An
HVAC purchase is a long-term commitment, so now is the
time to get the system that will satisfy your family's
needs. You can do this by reviewing the questions below.
Do
you want to lower your energy bills?
•If
you have high gas bills in the winter, ask about 95%
furnaces or higher.
•If you have high electric bills in the summer,
ask about 15 SEER or higher.
Would you like to reduce the amount of hot and cold
spots in your home?
•If
there are hot/cold spots predominately during mild temperature
days, then ask about your multi-stage options.
•Basic two-stage systems rely on two stages of
heating or cooling to give better comfort during mild
temperature days.
•Better two-stage systems use two stages of heating
and cooling plus a variable-speed blower to provide
more even temperature and fresh air in the home.
•The best is a modulating system that offers a
multitude of stages to provide the most precise temperature
control and comfort. Not all manufacturers have indoor
and outdoor modulating systems like Frigidaire.
Do you want to control temperature by room?
•Zoning
systems are designed to allow the homeowner to control
the temperature by room. You can zone as little as two
areas or you can zone up to eight. The ability to zone
your home, and the approach to zoning, may vary depending
on both the home layout and contractor skill.
Is it too humid in your home?
Does
it get too dry in the home?
Do
you have pets and the resulting dust and dander?
Is
dust a problem in your home?
Does
anyone in your family have allergies?
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Q.
What is Central air conditioning
?
A.
Central air conditioning, commonly referred to as central
air (U.S.) or air-con (UK), is an air conditioning system
that uses ducts to distribute cooled and/or dehumidified
air to more than one room, or uses pipes to distribute
chilled water to heat exchangers in more than one room,
and which is not plugged into a standard electrical
outlet.
With
a typical split system, the condenser and compressor
are located in an outdoor unit; the evaporator is mounted
in the air handler unit. With a package system, all
components are located in a single outdoor unit that
may be located on the ground or roof.
Central
air conditioning performs like a regular air conditioner
but has several added benefits:
When
the air handling unit turns on, room air is drawn in
from various parts of the building through return-air
ducts. This air is pulled through a filter where airborne
particles such as dust and lint are removed. Sophisticated
filters may remove microscopic pollutants as well. The
filtered air is routed to air supply ductwork that carries
it back to rooms. Whenever the air conditioner is running,
this cycle repeats continually.
Because the condenser unit (with its fan and the compressor)
is located outside the home, it offers a lower level
of indoor noise than a free-standing air conditioning
unit.
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Q.
What is Air Handler ?
A.
An air handler, or air handling unit (often abbreviated
to AHU), is a device used to condition and circulate
air as part of a heating, ventilating, and air-conditioning
(HVAC) system. An air handler is usually a large metal
box containing a blower, heating or cooling elements,
filter racks or chambers, sound attenuators, and dampers.
Air handlers usually connect to ductwork that distributes
the conditioned air through the building and returns
it to the AHU. Sometimes AHUs discharge (supply) and
admit (return) air directly to and from the space served
without ductwork.
Small
air handlers, for local use, are called terminal units,
and may only include an air filter, coil, and blower;
these simple terminal units are called blower coils
or fan coil units. A larger air handler that conditions
100% outside air, and no recirculated air, is known
as a makeup air unit (MAU). An air handler designed
for outdoor use, typically on roofs, is known as a packaged
unit (PU) or rooftop unit (RTU).
Blower/fanAir
handlers typically employ a large squirrel
cage blower driven by an AC induction electric motor
to move the air. The blower may operate at a single
speed, offer a variety of set speeds, or be driven by
a Variable Frequency Drive to allow a wide range of
air flow rates. Flow rate may also be controlled by
inlet vanes or outlet dampers on the fan. Some residential
air handlers (central 'furnaces' or 'air conditioners')
use a brushless DC electric motor that has variable
speed capabilities.
Multiple
blowers may be present in large commercial air handling
units, typically placed at the end of the AHU and the
beginning of the supply ductwork (therefore also called
"supply fans"). They are often augmented by
fans in the return air duct ("return fans")
pushing the air into the AHU.
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Q.
What is A Heat Pump ?
A
heat pump is a machine or device that diverts heat from
one location (the 'source') at a lower temperature to
another location (the 'sink' or 'heat sink') at a higher
temperature using mechanical work or a high-temperature
heat source.A heat pump can be used to provide heating
or cooling. Even though the heat pump can heat, it still
uses the same basic refrigeration cycle to do this.
In other words a heat pump can change which coil is
the condenser and which the evaporator. This is normally
achieved by a reversing valve. In cooler climates it
is common to have heat pumps that are designed only
to provide heating.
Common
examples are food refrigerators and freezers, air conditioners,
and reversible-cycle heat pumps for providing building
space heating. In heating, ventilation, and air conditioning
(HVAC) applications, a heat pump normally refers to
a vapor-compression refrigeration device that includes
a reversing valve and optimized heat exchangers so that
the direction of heat flow may be reversed. Most commonly,
heat pumps draw heat from the air or from the ground.
Heat
pumps have the ability to move heat energy from one
environment to another, and in either direction. This
allows the heat pump to bring heat into an occupied
space, or to take it out. In the cooling mode a heat
pump works the same as an ordinary air conditioner (A/C).
A heat pump uses an intermediate fluid called a refrigerant
which absorbs heat as it vaporizes and releases the
heat when it is condensed. It uses an evaporator to
absorb heat from inside an occupied space and rejects
this heat to the outside through the condenser. The
refrigerant flows outside of the space to be conditioned,
where the condenser and compressor are located, while
the evaporator is inside. The key component that makes
a heat pump different from an air conditioner is the
reversing valve. The reversing valve allows for the
flow direction of the refrigerant to be changed. This
allows the heat to be pumped in either direction.[citation
needed]
In
heating mode the outdoor coil becomes the evaporator,
while the indoor becomes the condenser which absorbs
the heat from the refrigerant and dissipates to the
air flowing through it. The air outside even at 0 °C
(or at any temperature above absolute zero) has heat
energy in it. With the refrigerant flowing in the opposite
direction the evaporator (outdoor coil) is absorbing
the heat from the air and moving it inside. Once it
picks up heat it is compressed and then sent to the
condenser (indoor coil). The indoor coil then injects
the heat into the air handler, which moves the heated
air throughout the house.
In cooling mode the outdoor coil is now the condenser.
This makes the indoor coil now the evaporator. The indoor
coil is now the evaporator in the sense that it is going
to be used to absorb the heat from inside the enclosed
space. The evaporator absorbs the heat from the inside,
and takes it to the condenser where it is rejected into
the outside air.
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Q.
What Is A Condenser?
What
is a condenser? Many people have air conditioners but
are not aware of how or what makes them work. A condenser
is simply one component of an air conditioner. Whether
you have an outdoor air conditioner or a window unit
air conditioner your air conditioner contains a condenser.
Condensers
are used in outdoor air conditioning systems as well
as heat pump systems. Condensers in an air conditioning
unit have very few controls. They will have an on and
off switch. Occasionally these air conditioners will
also have a brown out option. This option shuts down
the compressor when the electrical current is low.
A
condenser is simply a heat exchanger. It compresses
refrigerants into a hot gas to then condense them into
a liquid. A condenser is a major component in a air
conditioning or heat pump unit. It moves air across
the coils to facilitate the transfer of heat.
In
a heat pump unit the condenser has a few more features.
It will have a reverse valve that allows the unit to
switch back and forth between air conditioning and heating.
Even when the unit is heating, it uses the condenser
for defrosting the coils. If the coils become layered
with frost it will effect the units effectiveness this
is defrosted when the reverse valve switches to air
conditioning mode to move the hot gases through the
coils melting the built up ice. It will automatically
switch back to heating mode once the ice is cleared
to once again heat the home.
It
is very important no matter what type of unit you have
to prevent the blockage of the condenser. If the condenser
becomes block it can effect the units efficiency or
even cause the until to completely fail. For this reason
it is one of the most important components of a cooling
or heating system. A condenser allows the maximum airflow
to the unit.
To
keep your unit in good operating condition it is vital
to keep the area around the condenser clear of all debris
as well as keeping the filter clear of dust and dirt.
A clean machine makes a happy machine. A happy machine
will keep you cool during the summer months and warm
during the cold months. It is suggested to change the
units filters when they become dirty, depending on your
area and conditions near your home this may be as often
as once a month or as seldom as every 3 to 6 months.
You will have to pay close attention to your units needs
to decide the right time to change or clean your units
filters.
Keeping
you condenser in good running condition will not only
prolong the life of your heat or cooling system but
also provide you with the most efficient heat and cooling
system saving you money on heat and cooling.
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What
Is an Air Compressor ?
An
air compressor increases the amount of air in a particular
space. By packing in the air, the air pressure is increased
which creates a force that is useful for a variety of
purposes, from industrial and manufacturing to commercial
and personal purposes.
The
original air compressor is the lung. When you take a
deep breath to blow out your birthday candles, for example,
you're increasing the pressure of the air in your lungs,
which effectively is an air compressor containing pressurized
air. You then use the force of the air in your lungs
to blow out the flames of your birthday candles.
Eventually,
man-made air compressors were created. These fall generally
fall into one of two types, positive displacement or
dynamic, defined by its mode of operation. A positive
displacement air compressor works by filling and then
emptying an air chamber. Three common types of positive
displacement air compressors are: reciprocating, rotary
screw and rotary sliding vane. A dynamic air compressor,
on the other hand, uses a a rotating device to accelerate
and then decelerate air. This process uses the speed
or velocity of the air to increase the air's pressure.
Centrifugal air compressors are dynamic air compressors.
Compressed
air can be used in a variety of ways. It can be used
to alter the chemical composition as in the case of
making fertilizer or it can be used for industrial purposes
like production line manufacturing processes or it can
be used to maintain industrial plants. Perhaps the most
well known use of the air compressor is in the case
of pneumatic tools like air powered nail guns, staplers,
sanders, spray guns, or ratchet wrenches. Air compressors
can also be used to move debris. These tools are commonly
available at hardware stores for purchase or rental.
Another
way to group air compressor types is by the number of
stages it has. A two-stage air compressor is usually
used for heavy duty use. This type of unit offers a
higher level of compression than smaller, single stage
air compressors. A two-stage air compressor can store
air for future use, and is more energy efficient since
it produces more air per unit of horsepower than a single
stage compressor. Also, less heat is generated in a
two-stage compressor, which means that wear on the unit
is reduced. Portable electric air compressors are also
available for light-duty applications.
Depending
on the type of air compressor, operation costs can be
high, as in the case of plant maintenance. While air
compressors can run on manual labor, like a hand powered
air compressors, most run on either electricity or natural
gas. It's the natural gas air compressor that is usually
more cost-effective. If the air compressor is used in
a small, enclosed area, an electric model may be more
desirable in order to avoid gas fumes.
The
American Society of Mechanical Engineers (ASME) attests
to the quality and protective features of air compressors.
Their rating can be considered in evaluating air compressors
for purchase or rental. In some states, only ASME-certified
air compressors may be sold. Some safety features include
a safety relief valve, which lets air escape if the
tank's pressure exceeds the maximum. The air compressor
should also have a belt guard for protection, and an
enclosed air intake filtration system.
As
with all tools, proper safety should exercised when
using an air compressor. When not being used, air compressors
should be properly powered off and unplugged.
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How
does the heat work In central Air conditioners as Heat
Pumps?
Heat
pumps and most central air conditioners are called "split
systems" because there is an outdoor unit (called
a condenser) and an indoor unit (an evaporator coil).
The job of the heat pump or air conditioner is to transport
heat from one of these units to the other. In the summer,
for example, the system extracts heat from indoor air
and transfers it outside, leaving cooled indoor air
to be recirculated through your ducts by a fan.
A
substance called a refrigerant carries the heat from
one area to another. Basically, here's how it works:
The
compressor in your outdoor unit will change the gaseous
refrigerant into a high temperature, high-pressure gas.
As that gas flows through the outdoor coil, it loses
heat. That makes the refrigerant condense into a high
temperature, high pressure liquid that flows through
copper tubing into the evaporator coil located in your
fan coil unit or attached to your furnace.
At
that point, the liquid refrigerant is allowed to expand,
turning the liquid refrigerant into a low temperature,
low pressure gas. The gas then absorbs heat from the
air circulating in your home's ductwork, leaving it
full of cooler air to be distributed throughout the
house. Meanwhile, the low temperature, low pressure
refrigerant gas returns to the compressor to begin the
cycle all over again.
While
your air conditioner or heat pump cools the air, it
also dehumidifies it. That's because warm air passing
over the indoor evaporator coil cannot hold as much
moisture as it carried at a higher temperature, before
it was cooled. The extra moisture condenses on the outside
of the coils and is carried away through a drain. The
process is similar to what happens on a hot, humid day,
when condensed moisture beads up on the outside of a
glass of cold lemonade.
The
same process works in reverse in a heat pump during
the winter. The heat pump takes heat out of the outside
air - or out of the ground, if you have a geothermal
heat pump - and it moves that heat inside, where it
is transferred from the evaporator coil to the air circulating
through your home.
That's
not a typographical error, by the way- the heat pump
moves heat from outside to warm your home, even on a
cold day. That's because "cold" is a relative
term. Air as cold as 30 degrees still contains a great
deal of heat - the temperature at which air no longer
carries any heat is well below -200 degrees Fahrenheit.
A heat pump's heat exchanger can squeeze heat out of
cold air, then transfer that heat into your home with
the help of a fan which circulates the warm air through
your ducts.
Heat
pumps are often installed with back-up electric resistance
heat or a furnace to handle heating requirements when
more heat is needed than the heat pump can efficiently
extract from the air.
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What's the best way to
ensure that the central air-conditioning system you
choose is installed properly, and will provide the most
efficient and reliable cooling for your home?
The
pointers below can help you to find the right hardware
and the right technician to install your system, whether
you're replacing an older air conditioner or installing
one for the first time. The information comes from our
experts.
And
while there's no one money-saving strategy that will
work for everyone all the time, there are simple steps
that you can take, as we show in Keeping costs down.
In some cases, you may be able to cut back on air-conditioner
use considerably without seriously inconveniencing your
family.
Design
In a "split system," the typical design, refrigerant
circulates between an indoor coil and a matching outdoor
condenser with compressor. The refrigerant cools the
air, dehumidifying it in the process; a blower circulates
air through ducts throughout the house. A variation
is the "heat pump," a type of system that
functions as heater and cooler. When used as an air
conditioner, a heat pump discharges heat from the house
either into the air or deep into the ground. In the
winter, a heat pump extracts heat from the ground or
the air to warm the house.
Efficiency
This describes how much cooling the unit delivers for
each watt of electricity. Efficiency is expressed as
the Seasonal Energy Efficiency Rating, or SEER. At present,
a SEER of 10 denotes a low-efficiency unit; medium efficiency
is 11 to 14; high efficiency is above 14. New federal
regulations that took effect in 2006 set the minimum
SEER for a central air conditioner at 13.
Size
A synonym for the air conditioner's cooling capacity,
size is measured in British thermal units per hour (Btu/hr.)
or in "tons." One ton of cooling equals 12,000
Btu/hr.
Get
the right contractor
Finding a trustworthy contractor to install and service
an air-conditioning system matters the most. Here's
how to choose:
Ask
around
Seek referrals from neighbors, family, or business associates.
It's wise to get price quotes from at least three contractors.
Check
the background
Contractors who bid on your installation should show
you proof of bonding and insurance, plus any required
contractor's licenses. Check with your local Better
Business Bureau and consumer affairs office for complaint
records. It's a plus if technicians are certified by
a trade organization, such as North American Technician
Excellence or HVAC Excellence, to service residential
heating and cooling equipment. These and other similar
programs assess the technician's knowledge of specific
types of equipment and its proper service methods. We
believe that a contractor who has made the effort to
get certified and has practiced this trade and learned
from several years of service and installation experience,
will be a better service provider.
Get
specifics
Contractors who bid on your job should calculate required
cooling capacity by using a recognized method like the
Air Conditioning Contractors of America's Residential
Load Calculation Manual, also called Manual J. An additional
reference for assessing ductwork needs is Manual D.
The calculations produce a detailed room-by-room analysis
of cooling needs. Ask for a printout of all calculations
and assumptions, including ductwork design. Be leery
of a contractor who bases estimates merely on house
size or vague rules of thumb.
Expect
maintenance
A service plan that combines regular inspections with
discounts on repairs and a labor warranty is worth negotiating
into the overall price. Prices for such service vary
widely.
At
a minimum, regular inspections should include these
steps:
Check
for and repair refrigerant leaks.
Detect and correct duct leaks.
Inspect and tighten the electrical connections, checking
for damage.
Clean the coils, drain pan, and drainage system.
Vacuum the blower compartment.
Replace filter monthly or as recommended by the manufacturer.
Choose the right unit
If you're replacing an old central-air system, you can
expect to pay around $3,000 for the equipment. If you
need ductwork installed because you're starting completely
from scratch or are upgrading a forced-air heating system,
expect to pay $6,000 or more. Improving the system's
air-filtration capabilities is also easiest to do as
part of a general upgrade.
Brand
plays some role in the selection.
Here
are other factors that may affect reliability:
Matching
new equipment with old. If you replace only the condenser,
you have a "field-matched" system that can
be less efficient than advertised and that may require
more repairs because of undetected incompatibilities
between the two.
Damper-zoned cooling. A large or multistory house is
often divided into several heating and cooling zones
to improve temperature control. However, this type of
system is complex and has many more moving parts and
controls and so may require more repairs.
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HOW
TO MAINTAIN CENTRAL DUCT AIR CONDITIONING SYSTEM?
1.Troubleshoot
a Central Air Conditioning System
.........
Central
air conditioners have two separate components: the condenser
and the evaporator. The condenser unit is usually
located outside the house on a concrete slab. The evaporator
coil is mounted in the plenum or main duct junction
above the furnace.
Most
central air conditioners are connected to a home's forced-air
distribution system. Thus, the same motor, blower, and
ductwork used for heating are used to distribute cool
air from the air conditioning system. When a central
air conditioner is operating, hot air inside the house
flows to the furnace through the return-air duct. The
hot air is moved by the blower across the cooled evaporator
coil in the plenum and is then delivered through ducts
to cool the house. When the air conditioner works but
the house doesn't cool, the problem is probably in the
distribution system.
Both
the evaporator and the condenser are sealed. Therefore,
a professional service person should be called for almost
any maintenance other than routine cleaning. Central
air conditioners should be professionally inspected
and adjusted before the beginning of every cooling season.
However, don't let your maintenance end with this annual
checkup. While there aren't many repairs you can make
yourself, there are specific maintenance procedures
you can follow to keep your system operating at peak
efficiency.
Caution:
Before doing any work on an air conditioning system,
make sure the power to the system, both to the condenser
and to the evaporator assembly, is turned off.
2.Cleaning
the Evaporator
Cleaning
the Evaporator
The evaporator for the central air system is located
directly above the furnace in the plenum. The evaporator
may not be accessible, but if it is, you should clean
it once a year. If the plenum has foil-wrapped
insulation at its front, you can clean the evaporator;
if the plenum is a sealed sheet metal box, do not attempt
to open it. Here's how to clean an accessible evaporator:
Step
1: Remove foil-wrapped insulation at front of plenum;
it's probably taped in place. Remove tape carefully,
because you'll have to replace it later. Behind insulation
is access plate, which is held in place by several screws.
Remove screws and lift off plate.
Step
2: Clean entire underside of evaporator unit with stiff
brush. A large hand mirror can help you see what you're
doing. If you can't reach all the way back to clean
entire area, slide evaporator out a little. Evaporator
can be slid out even if it has rigid pipes connected
to it, but be careful not to bend pipes.
Step
3: Clean tray below evaporator unit. This tray carries
condensation away from evaporator. Pour 1 tablespoon
of household bleach into weep hole in tray to prevent
fungus growth. In extremely humid weather, check condensate
drain and pan every other day. If there's much moisture
in pan, weep hole from pan to drain line may be clogged.
Open weep hole with piece of wire.
Step
4: Put unit back into place, reinstall plate, and tape
insulation back over it.
Step
5: Turn back on air conditioner, and check for air leaks.
Seal any leaks with duct tape
3.Maintaining
the Condenser
Maintaining
the Condenser
In most air-conditioning systems, the condenser unit
is located outside the house and is prone to accumulate
dirt and debris from trees, lawn mowing, and airborne
dust. The condenser has a fan that moves air across
the condenser coil. You must clean the coil on the intake
side, so, before you turn off the power to the air conditioner,
check to see which direction the air moves across the
coils. Here's how to clean the condenser:
Step
1: Cut down any grass, weeds, or vines that have grown
around condenser unit; they could be obstructing airflow.
Step
2: Clean condenser with commercial coil cleaner, available
at refrigerator supply stores. Instructions for use
are included. Flush coil clean (do not use hose); let
dry.
Step
3: Clean fins with soft brush to remove accumulated
dirt. You may have to remove protective grille to reach
them. Do not clean fins with garden hose, as water could
turn dirt into mud and compact it between fins. Clean
fins very carefully: They're made of light-gauge aluminum
and are easily damaged. If fins are bent, straighten
them with fin comb, sold at most appliance parts stores.
A fin comb is designed to slide into spaces between
fins. Use it carefully to avoid damaging fins.
Step
4: Check concrete pad on which condenser rests to make
sure it's level. Set carpenters' level front to back
and side to side on top of unit. If pad has settled,
lift pad with pry bar or piece of 2-by-4, then force
gravel or rocks under concrete to level it.
During
the fall and winter, outside condenser units should
be protected from the elements to prevent leaf blockage
and ice damage. Cover the condenser unit with a commercial
condenser cover made to fit the shape of the unit or
use heavy plastic sheeting secured with sturdy cord
4.Handling
the Refrigerant (Only with help of licensed HVAC Contractor)
The
coolant used in most air conditioning systems is a refrigerant
called Freon. If the system does not contain the proper
amount of Freon, little or no cooling will take place.
If you suspect a Freon problem, call a professional
service person to recharge the system. Caution: Do not
try to charge your system's refrigerant lines.
Here's
how you can repair the system's coolant lines. Examine
the lines running from the condenser outside the evaporator
inside the house. If the insulation is damaged or worn,
it will cut down on the cooling efficiency of the unit
and, therefore, should be replaced.
Replace
damaged or worn coolant line insulation with new insulation
of the same type as soon as possible. Follow manufacturer's
instructions for installation.
Many
homes or apartments use window-unit air conditioners,
so it's also important to know how to maintain or service
these smaller units. Learn how to head off problems
and keep these units running smoothly in the next section.
5.Thermostat
The thermostat is located behind the control panel.
Here's how to test and/or replace the thermostat:
Step
1: Remove grille and control panel from unit. Thermostat
has special sensing bulb attached to it; this part extends
from thermostat into evaporator coil area. Its role
is to sense temperature, which is controlled by thermostat.
Step
2: Remove thermostat carefully because you must return
sensing bulb to identical spot later. To make replacement
easier, tag location of bulb before you remove thermostat.
Step
3: Check thermostat with VOM set to RX1 scale. Clip
probes of tester to thermostat terminals, and turn temperature
control dial to coldest setting. If meter reads zero,
thermostat is functioning properly. If reading is higher
than zero, replace thermostat with new one of same type.
If thermostat is held to control panel or frame with
screws, clips, or metal tabs, connect new thermostat
the same way the old one was connected.
Note:
If the thermostat has more than two lead wires connected
to it (not counting the sensing bulb wire) do not try
to test or replace it. Instead, call a professional
service person.
Drain
Ports
As the air conditioner operates, condensed moisture
and water vapor from the evaporator coil are funneled
through drain ports or an opening between the partition
in the middle of the evaporator coil and the condenser
coil. At this point, the fan blows the moisture against
the condenser coil, where the water is dissipated.
Drain
ports can become clogged with dirt. The result is water
leaking from the appliance, usually through the bottom
of the grille. To prevent clogging, clean the ports
with a short piece of wire hanger or the blade of a
pocketknife. Do this at the beginning of every cooling
season and every month during the season. Also check
the condenser side of the air conditioner. Some models
have a drain port along the bottom edge of the cabinet
frame. If your air conditioner has this drain port,
clean it out when you clean the other ports.
The
fan, motor, and compressor require routine maintenance
to keep your air-conditioning unit running at its most
efficient. The following are some simple guidelines.
6.Fan
When a fan malfunctions, the problem is usually loose
or dirty blades. If the fan won't operate or if it's
noisy, cleaning and tightening will usually fix it.
Here's how to repair a room air conditioner's fan:
Step
1: Open cabinet and locate fan.
Step
2: Clean away any debris with vacuum and soft cloth.
Step
3: Check fan blade on motor shaft for looseness. Blade
is fastened to shaft with setscrew at hub of blade.
Tighten
setscrew with screwdriver or Allen wrench. If air conditioner
has round vent fan, tighten fan on motor shaft by inserting
long-blade screwdriver through port in fan.
Fan
is installed in its housing with bolts, and vibration
can loosen these fasteners. Then tighten them with wrench.
Step
4: If fan has oil ports, apply several drops of 20-weight
nondetergent motor oil (not all-purpose oil) to each
port at beginning of cooling season.
Step
5: If you suspect fan motor is faulty, test it with
VOM set to RX1 scale. Disconnect terminal wires from
terminals, and clip probes of VOM to wires.
If
meter reads between about 3 and 30 ohms, motor is functioning
properly. If meter reads either zero or an extremely
high number, replace motor.
To
remove the fan motor, remove the fan, the power wires,
and several mounting bolts. Install the new motor with
the reverse procedure. However, if the condenser coil
must be moved to get the fan out, do not try to remove
the motor. Call a professional service person.
Motor
and Compressor
If problems occur in the motor or compressor of the
air conditioner, call a professional service person.
By
following the routine maintenance mentioned in this
article, you will be able to handle most problems that
occur with your central air conditioning or window unit.
Tips
for Buying or Upgrading your Central Duct Air Conditioning
System.
If you've been thinking of upgrading your old central
air-conditioning system, or installing central air in
a house that has never had it, there's a lot to consider.
Every manufacturer today offers a wide range of products,
with one suited to nearly every situation. A few even
make systems for houses that won't accommodate conventional
ductwork. As you might expect, the two most important
considerations are efficiency and cooling capacity,
but there's more to it than buying the biggest, most
efficient system you can afford. In fact, there's quite
a bit more.
1.
An Equipment Overview
Central
air conditioning is, of necessity, a split system, with
some components installed outdoors and others indoors.
The heaviest, noisiest, heat-shedding components–the
compressor and condenser coil–are installed outdoors,
while the evaporator coil is installed indoors, usually
in the form of an A-frame in the plenum of a forced-air
furnace. In this case, the furnace's blower moves warm
air over the coils and distributes the chilled air.
The indoor and outdoor segments of the system are typically
joined by two refrigeration lines and a low-voltage
relay cable.
If
a home is heated by some means other than forced air–baseboard
or radiant floor heat, for example–the evaporator
coil is typically mounted in a dedicated blower unit,
which pushes the cooled air through conventional ductwork.
Most blower units are installed in attics and crawlspaces
and are connected to flexible, insulated ductwork, which
is the easiest and least costly to install, especially
in retrofit situations.
In
houses built without ductwork, and where conventional
ductwork would be too costly or too inefficient to install,
a ductless central-air system is now possible. Ductless
systems have long been popular in Europe and Asia, where
building methods discourage ductwork, but are relatively
new in the United States. The Carrier Corp. is one of
several companies now making ductless systems for the
U.S. market.
In
these systems, a single outdoor compressor serves several,
smaller evaporator coils located indoors, each in its
own box and each with its own blower fan. These components
are installed on exterior walls, usually on the upper
half, where much of the heat accumulates. They're finished
unobtrusively, but they can be quite large, often measuring
6 x 18 x 24 in. Condensation lines are routed outside,
along with the refrigeration and electrical lines.
Ductless
systems can also provide heat, either through resistance
coils in the wall units or in heat-pump fashion. The
advantages of ductless air over window air are that
ductless systems move the noisiest components outdoors,
they can provide heat, they distribute the air more
evenly, and they don't block the better half of a window.
Installation costs vary widely, but ductless systems
can be more expensive than ducted systems. It's a sliding
scale, with each home's variables–primary building
material, number of rooms, house size and layout–coming
into play. They're reliable and efficient, but they're
not likely to replace ducted systems in the United States.
They're considered problem solvers, with the problem
being fairly rare.
2.
How Conventional Systems Work
All
heating and cooling technology grows from the law of
thermal dynamics that says when hot and cold spaces
are separated by a medium, the transfer through the
medium will always be from hot to cold. Heat follows
cold, whether the medium is human skin, an exterior
wall or the metal surface of an evaporator coil. When
warm, humid air is blown across the evaporator coil
in your furnace, the heat in the air is drawn to and
impinges on the cold metal surface of the coil's fin
tubes. In the process, the moisture in the air condenses
on the cold metal and drips into a pan below the coil,
where it's drained off, thus lowering the humidity in
the house.
It's
a neat trick–a double trick–but it requires
a repeatable cycle, over and over, every time the system's
thermostat demands it. The evaporator coil needs to
be constantly recooled and the heat it absorbs needs
to be carried outdoors. This is accomplished with a
liquid/gas refrigerant, which undergoes a pressure-induced
state change. An outdoor compressor pressurizes the
refrigerant, heating it to a gas state, then sends it
through an adjacent condeser coil to be cooled and returned
back to the evaporator coil. There it picks up household
heat and carries it back to the compressor. When this
cycle is repeated often enough, our homes become a lot
more comfortable.
3.
Understanding Energy Ratings
Air
conditioners have always been prodigious users of electricity,
but efficiencies have improved considerably in the past
few years. Part of this improvement was federally mandated
in 1990, through the culmination of the National Energy
Conservation Policy Act of 1971. These regulations established
minimum efficiency standards for heating and cooling
equipment. As a result, nearly all models manufactured
today are more efficient than those made just 10 or
15 years ago.
How
are systems rated? Central air conditioners–the
condenser units–are given a Seasonal Energy Efficiency
Rating, or SEER. In simple terms, SEER is calculated
by dividing the cooling capacity of a continuously operating
air conditioner by the electrical input required to
run it. The value is expressed in numbers. A SEER 10,
for example, is now the lowest number allowed, and any
number larger than that is accordingly more efficient
and will cost less to operate. Along with the yellow
Energy Guide tags attached to each appliance, these
ratings give consumers a benchmark sense of where their
choices fall on the energy-efficiency scale.
Most
manufacturers now offer SEER 10, 11, 12 and 13 models,
and some offer SEER 14. This gives you five separate
efficiency options, with model numbers usually keyed
to the SEER numbers, so they're easy to recognize. Lennox's
Value 12 system, for example, is a SEER 12.
4.How
Better Efficiencies Are Achieved
Like
the auto industry in its quest for better mileage, cooling
equipment manufacturers have combined some minor tweaking
with some major re-engineering. Because the compressor
is the biggest energy user, that's where they have focused
much of their attention. The first step was to improve
the internal components of standard, reciprocating compressors,
so that less pressure–and therefore, energy–was
lost to internal leaks. Another step was to increase
the size of the condenser coil. With more fin-tube surface
area, the returning refrigerant could be brought to
the compressor with less heat, reducing the compressor's
load.
These
two steps yielded substantial savings, bringing condensers
into federal compliance, but a complete retooling was
needed to achieve significant improvements beyond this
level. Part of the answer was a multispeed compressor.
With two or more speeds, the system doesn't have to
run full out on days when only mild cooling and dehumidification
are needed. Full-speed use is still available for those
really miserable days, but the compressor doesn't have
to run wide open all the time. At low speed, the practical
effect is that of a small compressor matched with an
oversize condenser coil. The savings can be substantial
and most manufacturers offer multispeed compressors
in their lineups.
At
the same time, engineers began testing a radically different
kind of compressor–the scroll. Scroll compressors
are so different that they practically defy description.
But their mechanical advantage is clear. Because they
generate much less friction, they experience much less
wear. The final product is a compressor that is very
efficient and lasts longer. Today, most companies offer
some multispeed and some scroll compressors, though
a few, like Ruud/Rheem, have gone to scroll compressors
exclusively, as a statement of across-the-line quality.
Any way you look at it, today's condenser units are
better than those made just a few years ago.
5.
The Freon Question
As
a result of the Montreal Protocol, a conference that
grew out of international concern over the ozone-depleting
qualities of CFC chemicals, the EPA is mandating the
gradual phaseout of Freon, or R22 refrigerant. The new,
non-ozone-depleting replacement will be R4-10A. In fact,
some manufacturers have switched to R4-10A in some models
already. While this new refrigerant works just as well,
it requires pressures up to 50% greater than Freon,
so it can't be used in existing equipment. Interestingly,
the higher operating pressure actually improves efficiency
slightly. In any case, there's no practical way to convert
existing equipment.
So
where does this leave the tens of millions of us with
Freon-based, R22 systems? The short answer is that the
Freon phaseout is stretched so far into the future that
nearly all of today's air conditioners will have been
replaced by then. The EPA will require a substantial
reduction by 2004, and all products containing R22 must
stop production by 2010. The production of R22 itself
must cease by 2020. For those few R22 units still in
service at that time, recycled R22 will be available,
though it will probably cost a small fortune.
6.
Sizing For Capacity And Efficiency
Your
heating, ventilation and air-conditioning (HVAC) contractor
will size your equipment to meet the specific needs
of your home. Factored into the equation will be the
age of your house, the number and quality of its windows,
how well it's insulated, how many stories it has, its
size, and, of course, local energy rates. Contractors
use industry sizing models, such as Model J, but most
use them as a reference, modifying the results to accommodate
their own years of experience. A 1500-sq.-ft. ranch-style
home, for example, might normally require a 2 1/2-ton
air conditioner, but if it's not well insulated, or
if a good many windows have western exposure, or if
the trees offer little direct shade, then a 3-ton unit
might be more appropriate.
In
any case, sizing is critical. If sized too small, the
system will struggle, and even freeze over, on the warmest
days. If sized too large, the system will cycle on and
off too frequently, greatly reducing its ability to
control humidity. It will also be less efficient. Keep
in mind that efficiency ratings are measured at the
factory, under conditions that may have little to do
with your house. In any case, sizing is a job best left
to seasoned professionals, and it's a good idea to seek
out more than one opinion.
7.
General Installation Costs
What
do air conditioners cost, installed? Again, local prices
will vary significantly, but in a typical Midwestern
town, a nonunion shop might charge between $1200 and
$1700 to replace an old, 3-ton air-conditioner with
a new SEER 10 system. That's assuming a 1500-sq. ft.
house, 20 years old, with ductwork in place. For a similar
home that's new, with a gas furnace and equivalent air
conditioning, the price would be $5000 to $7000, gas
and electrical connections included.
8.
The Price Vs. Efficiency Question
Of
course, you'll always pay more for high-efficiency appliances,
so the critical question is whether you'll save enough
in the long haul to come out ahead. And that, unfortunately,
requires a region-by-region, even a house-by-house,
assessment. You'll need to work closely with your contractor
to make an informed decision. Don't assume that high
efficiency always pays. It may from a good-citizenship
perspective, but real dollars should drive the rest
of the equation. And don't forget to add the cost of
interest on the money gained or lost.
All
we can do here is provide some context. If, for example,
your electricity costs you a low 6 cents per kilowatt-hour
(kwh), and you live in a reasonably well-insulated home
in the northern one-third of the nation, using your
air conditioner 200 to 400 hours per year, a basic SEER
10 system is probably your best choice. There's little
chance that you'd recover the several hundred extra
dollars a SEER 11 or SEER 12 system would cost, spread
over a 12- to 15-year projected service life. You may
hope for longer service, and you'll probably get it,
but don't count on it. A SEER 10 is also a reasonable
choice if you plan to move in the next few years.
On
the other hand, if you live in Yuma, Ariz., and run
your air conditioner 2000 hours per year, then it makes
sense to buy the most efficient model you can afford.
The same might be true if you live on the Eastern Seaboard
and pay 11 or 12 cents per kwh, or if you live in a
house with stone or brick exterior walls, where insulation
is simply not feasible. In these cases, high efficiency
really is a good investment.
Prices
vary by manufacturer and with local market pressures,
but it's probably safe to say that each step up in efficiency
will cost about $200. This may seem a paltry sum, and
it is for many people, but when you consider that the
equipment costs for an entire SEER 10 system might run
$800 to $900, an increase of $200 to $800 is significant.
9.
Quality And Warranties
Most
manufacturers offer two quality levels for each SEER
number. What you get in return is a better-made unit
that runs three to six times quieter and lasts longer.
A quieter-running unit can be a real plus if you–or
your neighbors–are particularly annoyed by a loud
air conditioner. You'll also get a better warranty:
a 10-year compressor warranty instead of five, a 5-year
warranty against leaks in the coils instead of one year.
As with all step-up warranties, you're betting against
yourself, which sometimes pays big dividends. If it
paid more than about 40% of the time, however, the manufacturer
couldn't afford to offer it.
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Important
information on Central ACs
Sizing
Up Your Central Air Conditioner Price Options
It takes more than a few figures and a form online to
thoroughly assess central air prices. There are several
factors that will directly affect the size of the unit
you need, what you’ll be spending up front, and
ultimately what you’ll be shelling out from month-to-month.
Central air conditioner prices go beyond the initial
cost of the unit itself, and all of these factors should
be considered when price shopping for a new air conditioning
system. The best way approximate your home cooling needs
is going to be doing a load calculation, or heat-gain
calculation. The Air Conditioning Contractors of America’s
Manual J Residential Load Calculation includes everything
from the obviously practical to the commonly overlooked
elements of home cooling, so it’s a great rubric
for determining prices of central air.
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Small
House, Round House, Big House: Central Air Conditioner
Prices Vary
The size of the area being cooled is an obvious factor
when it comes to sizing your potential AC unit. The
square footage of your home will directly affect your
home cooling needs.
The
size and position of windows and whether they have shading
contributes to the insulation in your home. If your
home is well insulated, you’ll have less need
for a larger central air system.
The
number of occupants changes both heating and cooling
needs. A full home will generally be warmer, thanks
to natural body heat. A larger house with fewer people
might need a little boost to keep things cool.
Home
appliances and electrical equipment create heat. If
your home is filled with heavy appliances and strong
lights that are often left on, you may need a stronger
central air conditioning system to combat the heat that
they create.
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Direct
Correlation Between a Homeowner's Central AC Prices
and their Central AC Unit's Seasonal Energy Efficiency
Ratio
The efficiency rating you’re aiming for will have
a drastic effect on your central air prices, both initially
and in the long run. The SEER (Seasonal Energy Efficiency
Ratio) is the most important factor to pay attention
to when shopping for efficiency. The simple breakdown
for efficiency ratings:
•16-23
SEER - $4,500 high efficiency, high prices, low month-to-month
costs
•14-17 SEER - $3,000 moderate efficiency
•13 SEER - $2,500 low efficiency, good for rentals,
economical buy
The more energy efficient your central air conditioning
system is, the more expensive the unit itself will be.
The SEER you aim for depends highly on the results of
your load calculation, your regional needs, and how
much you’re willing to spend on the future efficiency
of your central air conditioning system.
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What is the difference
between a condenser and compressor unit?
For home units, the compressor is the outside, large
box shaped unit that is usually on the side, or behind
the house. It takes the freon gas from inside the home
compresses it into a liquid, where it will be pumped
back inside to the condensor. Compressing gas creates
heat, so a fan draws air through the cooling coils on
the side of the unit, and blows it out the top. It is
important that these coils are kept clear of debris,
and should be periodically sprayed off with a hose to
knock off dust that may have accumulated.
Now
that the freon gas is compressed, it gets pumped inside
the house to the condensor, where the pressure falls,
allowing the freon to return to a gas. This creates
an endothermic reaction, drawing heat from the air.
The condensor unit has a series of coils with fins that
get very cold. The warm air in the house is blown over
these coils, cooling it, and then through the ductwork
of the house, and out through the registers.
The
A/C Compressor:
The
air conditioning compressor motor is a pump which draws
sensible heat laden refrigerant gas from the building's
indoor components (evaporator or "cooling coil"
in the indoor air handler) through the larger diameter
refrigerant suction line into the compressor where that
pump compresses the low pressure refrigerant gas to
high pressure and higher temperature.
Raising
the coolant (refrigerant) temperature above outdoor
ambient temperature causes heat to flow from the coolant
(flowing out of the compressor and through the outdoor
A/C condenser coil) into outdoor air. (Heat always flows
from warmer to cooler substances).
Sketch
courtesy of Carson Dunlop.
As
we explain at THERMOSTATIC EXPANSION VALVES, it is the
flow restriction provided by a cap tube or by a TEV
in the refrigerant piping system that allows the A/C
compressor pump to raise the system pressure and thus
increase the temperature at which the coolant changes
state. In other words, the TEV or cap tube allows the
compressor to reduce refrigerant pressure on the LOW
side of the metering device and raise refrigerant pressure
on the HIGH side of the metering device.
Incidentally,
A/C compressors can only accept and compress refrigerant
in gas form. In fact the refrigerant vapor is superheated
to be sure that there is no liquid at the pump - lest
the pump be damaged. If liquid refrigerant were to flow
into the compressor motor it would most likely cause
catastrophic damage.
The
A/C Condenser:
The
high pressure high temperature refrigerant gas leaves
the outdoor compressor and enters the outdoor condensing
coil where it is cooled to a liquid state by the condensing
unit fan that blows outside air across the condensing
coil or by immersion of the condensing coil in cooling
water in some designs.The heat produced in these steps
is transferred to the outside by a fan which blows outside
air across the condensing coil. The liquid refrigerant
is then able to return to the indoor components for
cooling and dehumidifying the building interior.
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Definition
of an Air Conditioner or Heat Pump
An
air conditioner or heat pump compressor is a basically
a motorized pump which moves refrigerant gas from the
indoor cooling coil (where it has evaporated to cool
indoor air blowing over that coil) to the outdoor compressor/condenser
where the gas is compressed and cooled back to a liquid
form. Refrigerant gas moves from the indoor air handler
cooling coil to the outdoor compressor via the larger
refrigerant "suction line". Liquid refrigerant
returns from the outdoor compressor/condenser to the
in-building air handler and evaporator coil. Evaporating
liquid refrigerant inside the indoor cooling coil cools
and dehumidifies indoor air. Condensing refrigerant
gas outdoors at the compressor/condenser effectively
is moving heat from indoors to the outdoor air. [During
heat pump "heating" cycles the process is
reversed, moving "heat" from outdoor air to
the indoor coil.]
The
diagnosis and repair of various defects in the air conditioning
compressor/condenser unit are discussed in detail using
the links provided at the left of this page. Here is
more detail about the components of the air conditioner
or heat pump compressor/condenser unit
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What
are the Components of the Outdoor Portion of a Central
Air Conditioning System - the Air Conditioning Compressor
Unit?
The
Air Conditioning Compressor Itself - on residential
units the A/C compressor motor is most often a hermetic
motor-compressor combined in a single sealed unit like
the Carrier™ unit shown at left.
You
cannot actually see the individual A/C compressor parts
because at least on residential air conditioners or
heat pumps, the entire assembly is enclosed. Sketch
from Carson Dunlop.
If
a ductless split-system air conditioner is installed
an outside compressor unit is still required, typically
looking like the Sanyo™ unit shown at the top
of this page.
If
a "portable" indoor air conditioner is in
use, all of these parts may be inside of a single portable
cooling unit, usually mounted on wheels. Portable air
conditioner units use a duct and fan system to blow
to outdoors the heat that has been extracted from indoor
air.
Window
air conditioners also contain all of these parts in
a single unit, but by hanging the window unit in a window
or in a wall opening, the device has ready access to
outdoor air into which it ultimately is transferring
heat from indoors.
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How
does an air conditioning compressor motor work?
The
job of the compressor/condenser unit is to recompress
warm refrigerant gas (pulled from the indoor air handler
cooling coil) back to a liquid refrigerant that can
be returned to the indoor cooling coil once again. When
the room thermostat calls for cooling, both the indoor
blower or air handler and the outdoor compressor/condenser
begin to work. Control circuits and a contactor relay
turn on the outside compressor/condenser motor and its
outdoor cooling fan as well.
The
air conditioning or heat pump compressor compresses
the incoming refrigerant to a high pressure gas and
moves that gas into the condensing coil described just
below. Typically a piston moves up and down inside of
a cylinder inside the compressor motor, drawing in refrigerant
gas on the down stroke of the piston, and compressing
the refrigerant gas on the up stroke of the piston.
(Some refrigeration compressors such as those made by
Frigidaire™ used a rotary compressor design that
we found durable and powerful enough to lead us to salvage
and re-use these motors for other purposes.
The
refrigerant gas leaves the compressor at high pressure
and at high temperature (since compressing a gas will
raise its temperature). In most air conditioning or
heat pump compressors, a piston moves up and down to
draw in and then compress refrigerant gas, moving refrigerant
vapor from the incoming low side to the outgoing high
side of the compressor.
The
refrigerant gas leaving the compressor (and entering
the condensing coil) will contain both heat that the
refrigerant absorbed at the evaporator coil (heat from
air in living space of the building), and additional
heat produced at the compressor by the process of compressing
the gas. The refrigerant gas is thus heat laden with
sensible heat (heat that we can measure) from the living
area and compressor heat from the compressor motor.
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What
is this Special oil used in air conditioning & refrigeration
compressor motors
Air
conditioning and refrigeration compressors use a special
oil which does not react with the refrigerant liquid
or gas in the system. The oil may mix and travel with
the refrigerant however, and some cooling systems are
designed for deliberate movement of the compressor oil
in order to lubricate some parts such as refrigerant
metering valves or compressor valves.
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What
are Refrigerant lines:
The
larger diameter refrigerant suction line connects the
indoor evaporator coil outlet to the compressor inlet.
The larger refrigerant line (located on the low side
of the system) reduces system pressure and causes vaporization
of the refrigerant (so that sensible heat is absorbed
and the suction line feels cool to the touch). Refrigerant
returning to the compressor from the evaporator coil
and through the refrigerant low pressure suction line,
is in the form of a low pressure, low temperature gas.
Most
air conditioning compressors are designed only to pump
gas vapors, not liquid refrigerant (which could damage
compressor internal parts).
The
refrigerant gas entering the compressor at its inlet
port is said to be heat laden, that is, it was at a
low-enough temperature to have absorbed heat from the
evaporator coil in the living area.
The
smaller-diameter high pressure refrigerant lines connect
the compressor outlet and the condensing coil inlet
and also move refrigerant liquid in it's cooled, condensed
and now liquid state from the outlet of the condensing
coil to the thermal expansion valve (basically a refrigerant
metering device) and the evaporator coil inlet in the
air handler unit in the building. This smaller (in diameter)
refrigerant piping or tubing (located on the high side
of the air conditioning system) reduces volume and thus
increases pressure and temperature in the lines (so
that sensible heat can be transferred to ambient outdoor
air or water if a water-cooled air conditioner system
is in use).
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What
is Service valves or ports
Service
valves or ports are usually present on the refrigeration
lines near the compressor. to permit testing the condition
of the air conditioning system and permit removal, replacement,
or additions to the refrigerant in the system.
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What
is Condensing coil ?
Condensing
coil receives high pressure refrigerant gas from the
compressor and cools this refrigerant gas back to a
liquid state.
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What
is Outdoor cooling fan
Outdoor
cooling fan moves outdoor air across the condensing
coil to cool it and assist in condensing the high pressure,
high temperature refrigerant gas back into a liquid.
It
is this process which completes the transfer of heat
through the refrigerant from indoor air to outdoor air
as the compressor/condenser unit compresses and then
cools the refrigerant back to a liquid.
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