13
CONDENSATE DRAIN
Condensate Drain Connection
A 3/4” NPT drain connection is supplied for condensate
piping. An external trap must be installed for proper
condensate drainage.
DRAIN
CONNECTION
M
U
M
I
N
I
M
"
2
T
I
N
U
FLEXIBLE
TUBING-HOSE
OR PIPE
3" MINIMUM
A POSITIVE LIQUID
SEAL IS REQUIRED
Drain Connection
HEAT PUMP OPERATION
Heating Cycle
The heat pump operates in the heating cycle by redirecting
refrigerant flow through the refrigerant circuit external to the
compressor. This is accomplished through the reversing
valve. Hot discharge vapor from the compressor is directed
to the indoor coil (evaporator on the cooling cycle) where
the heat is removed, and the vapor condenses to liquid.
It then goes through the expansion device to the outdoor
coil (condenser on the cooling cycle) where the liquid is
evaporated, and the vapor goes to the compressor.
When the solenoid valve coil is energizing for cooling,
the piston in the reversing valve to the low pressure (high
pressure) reverse positions in the reversing valve. In
addition to a reversing valve, a heat pump is equipped
with an expansion device for the indoor coil, and similar
equipment for the outdoor coil is provided with a defrost
control system. The expansion devices are flowrator
distributors and perform the same function on the heating
cycle as on the cooling cycle. The flowrator distributors
also act as check valves to allow for the reverse of
refrigerant flow. When the heat pump is on the heating
cycle, the outdoor coil is functioning as an evaporator. The
temperature of the refrigerant in the outdoor coil must be
below the temperature of the outdoor air in order to extract
heat from the air. Thus, the greater the difference in the
outdoor temperature and the outdoor coil temperature,
the greater the heating capacity of the heat pump. This
phenomenon is a characteristic of a heat pump. It is
a good practice to provide supplementary heat for all
heat pump installations in areas where the temperature
drops below 45°F. It is also a good practice to provide
sufficient supplementary heat to handle the entire heating
requirement should there be a component failure of the
heat pump, such as a compressor, or refrigerant leak,
etc. Since the temperature of the liquid refrigerant in the
outdoor coil on the heating cycle is generally below freezing
point, frost forms on the surfaces of the outdoor coil under
certain weather conditions of temperature and relative
humidity. Therefore, it is necessary to reverse the flow of
the refrigerant to provide hot gas in the outdoor coil to melt
the frost accumulation. This is accomplished by reversing
the heat pump to the cooling cycle. At the same time, the
outdoor fan stops to hasten the temperature rise of the
outdoor coil and lessen the time required for defrosting.
The indoor blower continues to run and the supplementary
heaters are energized.
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