Dual Fuel
How do I configure Dual Fuel?
Setting Up Dual Fuel
Setting the thermostat up for dual fuel is fairly painless. If you are using a fully communicating outdoor heat pump such as a (-)P17 or (-)P20 most of the work is already done. The EcoNet gas furnace and heat pump will be acknowledged. The outdoor sensor in the Heat Pump will be used and there is no need to add one.
If you are using a communicating gas furnace with a non-communicating heat pump, you will need to assign that in the outdoor unit settings screen first by going to the settings screen, then installer (for the 700 series you will have to hold installer for about 5 seconds) and AC/HP. You will also need to add an outdoor sensor wire back to the gas furnace IFC.
The main thing you need to do as a technician is set the balance points for the customer. Enter the settings screen, go to installer and select AC/HP button. Toward the bottom you will see…
Heat Source: BOTH
Furnace Locked Out Above: Disabled
Heat Pump Lock Out Below: Disabled
For Heat Source, this is where you decide if you want true dual fuel, furnace only or heat pump only operation. If set to BOTH, it will work as dual fuel.
For Furnace locked out above, this is the outdoor temperature that you don’t want any supplemental assistance from the gas furnace. The furnace will still operate above this temperature when put into emergency heat mode or if there is a fault in the outdoor unit. It just won’t switch over to gas above this temp if someone turns the thermostat up or the unit falls behind.
For Heat Pump Lock Out Below, this is the outdoor temperature at which you want the heat pump to shut down and switch over to gas furnace for all heating calls.
Example Settings:
Heat Source: BOTH
Furnace Lock Out Above: 30°F
Heat Pump Lock Out Below: 10°F
In this scenario, the heat pump will do all the work to heat the home down to 30°F and even down to 10°F. If it is below 30°F the gas furnace can be called on to assist if the inside temperature falls too far below set point. Once it gets below 10°F outside, the system will automatically turn off the HP and turn the gas furnace on for full heating responsibility.
