Heat pump heating systems
A heat pump is a central forced air heating and cooling system equipped with a thermostat.
Most heat pumps are called "air source" heat pumps because they derive
their heat from the outside air.
They have two main parts, an outdoor unit with a heat exchanger, compressor and
fan, and an indoor unit with a heat exchanger and air handler.
Another type of heat pump is called a "water source" heat pump. This type
of heat pump has one unit with two heat exchangers, a compressor, and an air handler.
Both types have reversing valves for cooling.
Heat pumps operate like a refrigeration cycle. The cycle moves heat from a cooler
area to a warmer area much like your home refrigerator. Air is moved over an outside
coil extracting heat.
The heat is transferred through an inside coil and then distributed through ducts.
By reversing the cycle, the system will act as an air conditioner. A heat pump does
not generate heat like other heating systems. Instead, it moves heat from one place
to another.
The thermostat starts or shuts off the refrigeration cycle according to the set
temperature. If for some reason the heat pump cannot maintain the desired temperature,
the backup heat comes on. When the set temperature is sensed by the thermostat,
the system shuts off.
Adjusting the thermostat up and down can force the backup heat to come on and will
increase the cost of operation, unless you have a "smart" thermostat,
which brings up the heat slowly and prevents the back up heat from coming on.
Maintenance of your heat pump is important. You should replace the filters once
a month during the heating season or clean the filter if the system has a permanent
one. Keep the registers open and clear from blockage, and keep the outdoor unit
free of debris.
By maintaining good air flow you will extend the life of your unit. The heat pump
should be serviced each year before the heating season. The service call could include
cleaning the coils, cleaning and lubricating fans, checking temperatures across
heat exchangers, checking refrigerant pressure, checking electronic components and
calibrating the thermostat.
Many thermostats do not accurately measure the room temperature. This means that
although you set the thermostat to 68 degrees it may actually allow the room temperature
to climb several degrees higher than your "set point" before shutting
the system off. To check the accuracy of your thermostat, place a thermometer in
a central location in the room. Check the thermometer reading against the reading
on your thermostat. Are they the same? Experiment with the thermostat so you will
know where to set it next time. Remember, the lower you keep the temperature setting,
the lower your energy costs.
There are many options available for heat pumps. These include: clock thermostats,
a variety of compressors, electronic controls and electrostatic filters.
An efficient heat pump uses approximately one-third the energy of a resistance heating
system, such as electric forced air. When including backup heat and defrost cycle,
a heat pump averages about one-half the cost of electric forced air heat. You can
reduce the operation cost further by using a "smart" thermostat and setting
it at 68 degrees.
If the unit does not run, the power could be off, or there could be a blown fuse,
or the thermostat may not be set properly.
If the auxiliary or emergency heat light is always on when the unit is running,
there is some problem with the system. It could be a clogged or dirty filter, blocked
registers, debris on the outside coil, the compressor may be low on refrigerant,
or there could be other internal problems. If there is an increase in electrical
usage for no apparent reason, the compressor may not be working and you may be operating
expensive back-up heat.