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the heat pump back may be erased by the auxiliary heaters when the heat pump tries to recover from the
setback. A PESM will work best with heat pumps that have one or more of the following features:
a. An outdoor temperature switch that prevents the auxiliary heat from coming on unless it is very cold outside.
This is sometimes called a "heat balance" switch.
b. A thermostat that uses rate of rise to determine if auxiliary heat is necessary: The Enerstat Model DSL-450.
When recovering from setback, the thermostat runs the heat pump first. It will run the auxiliary heat only if
the rate of temperature rise is less than 6 degrees F. per hour.
c. An alternative auxiliary heat source that is inexpensive (i.e. gas).
These features will avoid the use of auxiliary heat (usually an electric strip heater) which is more expensive than
using the heat pump when recovering from setback. In general, heat pumps take a longer time to recover from
setback, so it may be advantageous to program a setback only for extended periods, such as a vacation.
TEMPERATURE, OUTDOOR TEMPERATURE, AND HUMIDITY
When connected to the controller, the Model 31A00-1 (31A00-7 Extended Range) Indoor/Outdoor Temperature and
Model 31A00-2 (31A00-8 Extended Range) Indoor/Outdoor Temperature and Humidity Sensor is used for sensing
indoor temperature and/or reporting the relative humidity from 0 to 100 percent or for sensing the outdoor temperature
and/or reporting the outdoor relative humidity. The outdoor temperature can be displayed on the console, spoken
over the telephone, or displayed on an Omnistat Thermostat.
1. Each Temperature Sensor requires one zone input. Each Humidity Sensor requires one zone input.
- Program the zone type as an Outdoor Temperature (Type 81), Temperature (Type 82), Temperature Alarm
(Type 83), for temperatures between 0
o
F - 120
o
F
- Humidity (Type 84), for humidity between 0% – 100%
- Extended Range Outdoor Temperature (Type 85), Extended Range Temperature (Type 86), and Extended
Range Temperature Alarm (Type 87), for temperatures between -40
o
F - 120
o
F
2. When mounting outdoors, plan to mount under an overhang or to the underside of an eave, also known as the
soffit, to protect it from direct sunlight and rain. Run a 4-conductor wire from the Omni LTe controller to the
selected location.
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