Heat pump with gas furnace?

sorry if this is a dumb question, can a heat pump be installed with a gas forced air furnace?

Of course Bob…it’s all in the thermostat wiring.

Yep, the gas furnace just becomes the “emergency heat” instead of electric strips.

I’ve even seen them with oil furnaces. (back in the old days when I lived in a colder climate!:smiley: )

Called a dual fuel system

in this case, i dont understand the purpose. it was a HUGE 3600 sq ft house with two furnaces. main was 200K btu, other (for upstairs) 60k. why would a 200k btu furnace have a heat pump installed??

how can you tell if a heat pump is installed?

For cooling

If it is truly installed and used as a heat pump, then there will be a “EMERG” position on the thermostat for heating purposes; also, on the AC condenser there should be 3 nipple fittings instead of 2.

Maybe the heat pump was installed later.

Heat pumps are installed on gas and oil furnaces with an interface device called a “fossil fuel kit”](http://www.jacksonsystems.com/pdf/ffk100operation.pdf). This is a safety device and an energy saving device both.

Heat pumps on fossil fuel furnaces often also have an outdoor thermostat that will lock out the heat pump at a certain outdoor ambient temp and permit the fuel burning heating appliance to take over. This permits the heat pump to run during temperatures where it’s cheaper to run the heat pump, and lets the fuel burning heating appliance take over at an outdoor ambient where it’s more effieient to burn fossil fuel.

ok, whats the difference between an a/c unit and a heat pump?

An air conditioner is a heat pump–it just works one way.

The heat pump removes heat from outside and uses it to warm the house inside.

The A/C removes heat from the house and thus lowers the temperature inside.

The thermostat controls either function by activating a reversing valve in the condensing unit.

The difference between a heat pump and a conventional A/C unit.

In the normal heat mode for a heat pump the outside condenser becomes the A-coil and the inside A-Coil on the air handler becomes the condenser. This as JAE stated is accomplished with a reversing valve that is visible thru the top of the outside unit below the condenser fan. Heat inside the home is accomplished simply reversing the flow of freon nothing magic.