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20
Heat Pumps and Energy
Savings
• Heat Pump Operation - Zoneline 5500 Series
Heat sources: Heat pump, heat pump and simultaneous
electric resistance heat, or electric resistance heat
The Zoneline 5500 Series heat pumps employ a highly
featured microprocessor control system interfaced with
thermistors to accurately measure indoor air temperature,
outdoor air temperature, indoor coil temperature, and
outdoor coil temperature. This system allows the
microprocessor to precisely and predictably react to
changing conditions in order to provide a very advanced
Packaged Terminal Heat Pump operating system.
The Zoneline 5500 series is designed to help insure a
comfortable room. When “HEAT” is selected, the unit will
determine if the room air is warm enough to satisfy the
thermostat setting. If the temperature at the unit sensor is
below the desired temperature, the electric resistance heater
will be utilized to warm the room to the point where the
thermostat is satisfied. This feature is designed to allow the
temperature of an unoccupied room to be maintained at an
energy saving level without inconveniencing the room
occupant. Once the thermostat has been satisfied, the
resistance heater will turn off and the heat pump will operate
as shown in Zoneline 5500 Series Heat Source Logic chart
when the thermostat calls for heat again. The unit will operate
in this manner even if connected to a Central Desk Control.
*If the “Temperature Boost” switch (dip switch #8) is in the
“ON” position, the supplemental simultaneous heater will be
used with heat pump operation. Simultaneous supplemental
heater: 1.0 KW @ 230 V; 0.8 KW @ 208 V; 1.7 KW @ 265 V
The “Temperature Boost” option utilizes the supplemental
simultaneous heater simultaneously with heat pump
operation when the outdoor temperature is below 46°F.
regardless of the indoor air temperature. The chart above
indicates the heat source of the Zoneline 5500 series heat
pump under various indoor and outdoor conditions. The
unit is designed to provide heat pump savings without
sacrificing room comfort. The Quick Heat Recovery feature
is not affected by the Zoneline 5500 Series Heat Source
Logic shown in the chart above. For more information
about the Quick Heat Recovery Feature, see page 9. The full
heat output of the resistance heater is dependent upon
circuit amperage and the power connection kit used. See
pages 42 - 43 for information on the power connection kits
and available heater capacities.
A heat pump override switch is provided in the auxiliary
controls to allow the unit to operate only in resistance heat.
The use of this option significantly increases the cost for
heating.
Heat pump defrost - Zoneline 5500 Series
The Zoneline 5500 Series has a reverse cycle demand
defrost system to extend heat pump operation and increase
savings from extended operation. The microprocessor
determines the need for defrosting by criteria based on
continuous compressor running time, outdoor air
temperature, outdoor coil temperature, and the rate of
temperature change of the outdoor coil. When defrosting is
required, the unit reverses the flow of refrigerant to direct
the hot gas into the outdoor coil to melt the frost build-up.
Before and after the reverse cycle defrosting, the unit shuts
off the compressor to allow the refrigerant pressures to
equalize throughout the system. This eliminates the
possibility of a loud reversing noise. During these periods of
pressure equalization, the full resistance heat capacity of the
unit is activated to help insure room comfort conditions
during the defrost cycle. The unit remains in the defrost
cycle for a minimum of 2 minutes up to a maximum of 9
minutes. The defrost cycle terminates when the outdoor coil
reaches a temperature of 68°F or the maximum time has
been reached.
Heat pump condensate See page 34 for information on
heat pump condensate. The Zoneline 5500 Series heat
pump may be ordered with a factory installed Internal
Condensate Removal (ICR) system to minimize the amount
of condensate water draining from the unit during heat
pump operation.
ROOM
TEMPERATURE
VS. THERMOSTAT
SET POINT
Less Than 1.8°F.
Below
1.8°F to 2.7°F.
Below
More than 2.7°F.
Below
Above 46°F.
Heat Pump
Heat Pump
Heat Pump
Between 46°F.
and 25°F.
Heat Pump*
Heat Pump +
Supplemental
Heater
Full Resistance
Heat
Below 25°F.
Full Resistance
Heat
Full Resistance
Heat
Full Resistance
Heat
Zoneline 5500 Series Heat Source Logic
2020 Data Manual 2002 11/7/02 3:19 PM Page 20
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