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How do I control a dual fuel Heat Pump?

Provide Low Supply Temperature Notification

This configuration can be set in the Pelican Web-App > Admin > Thermostat Configuration > ‘select any thermostat‘ > Input Sensor > Function: Supply Temperature > Cool Safe Range.

The Cool Safe Range tells the thermostat that if the thermostat is in a cooling cycle (compressors are enabled) and the supply temperature is not within the configured temperature range within 4 minutes after the compressors were enabled, then to send a notification.

Because this is a range, if the temperature is below the configured range, then a low temperature notification will be sent.

Note: This configuration is only available if the thermostat has a supply temperature sensor wired to it.

Wiring a Pelican thermostat to a Heat Pump unit with dual fuel:

Wire your Pelican thermostat to enable the first compressor with (Y), the second compressor with (Y2), the fan with (G), the reversing valve with (W), and the secondary heating source with the (W2).

Each Pelican thermostat has a configuration called Compressor Lockout*.

You can use Compressor Lockout to prevent the thermostat from enabling the compressors once the outside temperature is below a configured value. Instead the thermostat will use the secondary heating source as its primary heating source to warm the room.

*Note: The Compressor Lockout configuration is only available if your Pelican Solution has an outside temperature sensor part of the overall system. The system automatically shares a single outdoor temperature to all thermostat for Compressor Lockout.

How to configuration the thermostat correctly for a dual fuel Heat Pump:

These first configurations can be found in the Pelican Web-App > Admin > Thermostat Configuration > ‘select any thermostat‘ > Thermostat Settings.

System Type: Heat Pump

Heat Stages: Set to the number of compressor stages the Heat Pump has.

Cool Stages: Set to the number of compressor stages the Heat Pump has.

Reversing Valve: Set to when the thermostat should enable the reversing valve (either during a compressor heating or cooling cycle).

Aux Heat: Set to Emergency. This tells the thermostat to use the secondary heating source if the Heat Pump’s compressor(s) have been running for one (1) hour, but are unable to warm the room to at least 1°F below the heat setpoint (in other words, the Heat Pump has failed to heat the space).

This last configuration can be found in the Pelican Web-App > Admin > Thermostat Configuration > ‘select any thermostat‘ > Thermostat Operation.

Compressor Lockout*: You can set this to any temperature between 0 and 100°F. This should be set to the recommended outside temperature for both when the Heat Pump will be unable to produce an adequate amount of heating output to warm the space and it becomes dangerous to enable the compressor(s) because it is too cold outside and the oil in the compressor(s) will not lubricate the compressor motor adequately. 

What will happen with these configurations?

During periods where the outside temperature is above the Compressor Lockout setting, the thermostat will use the Heat Pump as the primary heating source and will only enable the secondary heating source if the Heat Pump fails to heat the room (an alarm will be generated if this occurs). Once the outside temperature is below the Compressor Lockout setting, the thermostat will not enable the Heat Pump’s compressors and instead automatically switch to using the secondary heating source as its primary heating source to warm the space.

The web-app tracks and displays, in real-time and historically, when and if the Heat Pump is running, how many compressors are running, and when the secondary heating source runs.