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7
EXTENDED HEAT PUMP OPERATION/
REVERSE CYCLE DEFROST
Heat exists in the outdoor air at temperatures even below
0°F. Many central systems, with larger outdoor coils, operate
in the heat pump mode down to temperatures in the mid-
teens or even to single-digit temperatures. Central systems
are able to operate at temperatures this low because of
the larger outdoor coil area, and because central system
heat pumps have a reverse cycle defrost mode that melts
accumulated frost off the outdoor coil.
Other single packaged vertical heat pump units terminate
heat pump operation and switch to more expensive
resistance heat at outdoor temperatures in the 40°F. to
45°F. range. They must terminate heat pump operation
before a frost build-up occurs on the outdoor coil since
they have no way of eliminating the frost.
GE
Appliances
offers a reverse cycle defrost system, like the
central systems, on all Zoneline
®
single packaged vertical heat
pumps. This provides the owners with the savings realized by
the ability to operate in heat pump mode even when outdoor
temperatures drop. GE
Appliances
has adapted the reverse
cycle heat pump defrost system to the
SPVU
for greater
savings in heat pump mode.
The
SPVU
will operate in efficient heat pump mode down to
a 25°F. outdoor temperature. At temperatures below 25°F.,
the unit will automatically switch to electric heat. When the
outdoor temperature rises to 32°F., the unit will automatically
switch back to heat pump operation. As long as the heat pump
output is able to maintain the room temperature within 4°F.
of the thermostat set point, the unit will run in heat pump
mode down to 25°F. outdoor air temperature. The resistance
heater and the heat pump do not operate simultaneously.
If the outdoor temperature is above 25°F. and if the room
temperature falls more than 4°F. below the set point, the
thermostat automatically switches the unit to resistance heat.
If frost develops on the outdoor coil at temperatures above
25°F., the unit initiates the reverse cycle defrost operation
to warm the outdoor coil and allow the unit to resume heat
pump operation.
Prior to initiating the defrost sequence, the electric heaters
will be energized to bring the room to the thermostat set
point. Immediately after the defrost is completed, the electric
heaters are energized to bring the room back to proper room
temperature. The defrost sequence is terminated when the
outdoor coil reaches 68°F. or when nine minutes have elapsed.
CONCEALED MANUAL VENT CONTROL
Open ventilation doors on GE
Appliances
Zoneline Single
Packaged Vertical Air Conditioners and Heat Pumps allow
outside air to enter the room through a screen-covered
opening in the weather barrier that separates the indoor and
outdoor sections of the unit. For each CFM of air to enter
the room, an equal amount of air must be removed through
exhaust fans in the bathroom or rooftops. Outside ambient
air entering the room through this screened vent opening is
not conditioned. This unconditioned air becomes mixed with
the conditioned air that is circulated by the
SPVU
indoor
fan. This air mixture generates an additional heat load/heat
loss that causes the unit to run longer and may translate into
higher operating costs.
A concealed lever located behind the front cover of the
SPVU
is used to open and close the vent door. Zoneline
vent openings are not intended to be the source of make-up
air for building ventilation systems due to the additional
heating or cooling loads generated.
VENTILATION CFM AT VARIOUS ESP POINTS:
For warranty information, see page 17.
VENTILATION (CFM)
STATIC PRESSURE
INCH WATER
9,000
BTUH
12,000
BTUH
18,000
BTUH
230V 230V 230V
0.0 62 68 70
0.1 52 61 65
0.2 46 57 62
0.3 41 52 57
0.4 34 45 50
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