York Heat Pumps: YorkGuard VI
Re: Add-On Heat Pump ("Fossil Fuel") Operation
When a heat pump equipped with a YorkGuard VI module is installed in an "Add-On" or "Fossil Fuel" application, the YorkGuard handles all of the "Fossil Fuel" sequences with the addition of a "Bonnet Sensor" between the gas furnace and indoor coil.
- Configure the thermostat for standard Heat Pump operation.
- No additional outdoor sensor required.
| YorkGuard VI - "Fossil Fuel" Sequence of Operation |
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For Fossil Fuel Operation, the following setting must be made on the YorkGuard:
- FFUEL = Set to "On"
- BP = Set for 45, 40 or 35 deg.
- LTCO = Set for 20, 15 or 10 deg.
- Bonnet Sensor installed & wired to "BS" and "BSG"
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| 1. Outdoor above Balance Point (BP) |
- On a call for "Y1" the YorkGuard energizes the compressor for 1st Stage heating.
- On a call for "Y2" the YorkGuard energizes the compressor unloading solenoid to put the compressor in full operation.
- The YorkGuard also energizes "Y2 Out" to tell the variable speed indoor fan to go to "High Heat" speed.
- On a call for "W" (or "Aux") the YorkGuard will keep Aux Heat outputs "W1 Out" and "W2 Out" de-energized.
- If the heat pump goes into a Lockout condition, the YorkGuard will automatically energize "W1 Out" to satisfy heating demand.
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| 2. Outdoor below Balance Point (BP) |
- On a call for "Y1" the YorkGuard energizes the compressor for 1st Stage heating.
- On a call for "Y2" the YorkGuard energizes the compressor unloading solenoid to put the compressor in full operation.
- The YorkGuard also energizes "Y2 Out" to tell the variable speed indoor fan to go to "High Heat" speed.
- On a call for "W" (or "Aux") the YorkGuard will energize "W1 Out" to start the furnace while keeping the compressor operating.
- The compressor continues to operate until the Bonnet Sensor temperature reaches 90 deg.
- If the furnace fails to operate the heat pump will continue to operate to try to maintain heating.
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| 3. Outdoor below LTCO |
- The YorkGuard basically enters Emergency Heat mode.
- On a call for "Y1" the YorkGuard keeps the compressor off and energizes "W1 Out" to start the gas furnace.
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