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Freeze protection (optional)
The unit shuts down when it receives a freezestat status.
Fan
The fan runs when the unit runs, unless safeties stop the fan. The fan runs for 5 minutes
after the heating or cooling coils go inactive, to cool or dry the coils.
Heating and cooling - 2 compressor stages
The Room Controller measures the zone temperature and stages the compressors to
maintain setpoint. A 5-minute delay between stages prevents short cycling, and each
stage has a 2-minute minimum on time and a 4-minute minimum off time. The
compressor runs subject to its internal safeties and controls.
Heating is enabled when:
•
The zone temperature is below the heating setpoint, and
•
The fan status is on, and
•
The reversing valve is in heat mode.
Cooling is enabled when:
•
The zone temperature is above the heating setpoint, and
•
The fan status is on, and
•
The reversing valve is in cool mode, and
•
The economizer operation (if enabled) is not maintaining the zone temperature.
The compressor turns off for 30 seconds after the reversing valve changes position.
Supplemental heating stages
The Room Controller measures the zone temperature and stages the heating to maintain
heating setpoint if the compressors do not meet the heating demand. A 5-minute delay
between stages prevents short cycling, and each stage has a 1-minute minimum on time
and a 1-minute minute minimum off time.
The heating is enabled when:
•
The heat pump has been running both stages in the heat mode for at least 10
minutes, or
•
The zone temperature is more than 2°F (1°C) below heating setpoint.
Economizer (optional):
The Room Controller measures the zone temperature and modulates the outside air
dampers to maintain the cooling setpoint. The Room Controller opens the outside air
dampers to at least a configurable minimum position to provide ventilation when the
room is occupied. The Room Controller closes the outside air dampers completely when
the freezestat is on.
The economizer is enabled when:
•
Outside air temperature is at least 3°F (1.5°C) less than the zone temperature, and
•
The outside air temperature is less than 70°F (21°C), and
•
The fan is running, and
•
Heating is not on.
