Thread: Heat Pump Question

I want to make sure I am testing the gas furnace correctly.(gas forced air) If there is a heat pump on the system, do I go to regular heat or emergency heat when I push the thermostat up to check the tempature on the supply registers?

Please explain. Heat & air is not my specialty.

Thanks Gary

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Gary, with a heat pump and a gas fired forced air furnace in the same house, the heat pump (from my experience) is typically the primary heat source with the gas furnace being the backup. The thermostat should be a heat pump thermostat with an emergency backup heat mode. To test the furnace, put thermostat in emergency backup mode and push the thermostat setting up above the ambient air temperature in the room. That should activate the furnace.

If you are not comfortable with HVAC, it would be money well spent to take an HVAC training course and/or ride along with a current inspector to see how somebody else inspects HVAC systems. If you do the ride alongs, ask plenty of questions, take plenty of notes.

Thanks ! That really helps. I have been on a couple ride alongs but mostly seeing package / combination systems. I have been doing the exterior while the other inspector is on the inside. (we'll swap up later).

Another question???

Is the only way to know if you have a heat pump is by looking for the reversing valve in the condensing unit? Or will the thermostat always tell u with with emergency heat or aux. heat modes on the thermostat?

Originally Posted by Gary Winfield

Is the only way to know if you have a heat pump is by looking for the reversing valve in the condensing unit? Or will the thermostat always tell u with with emergency heat or aux. heat modes on the thermostat?

Look for the data plate and the reversing valve at the exterior unit, don't trust the thermostat to tell the tale, I've seen more than one incorrect stat.
Also, check for function. An outdoor heat pump can be used as an air conditioner without being wired or otherwise configure to work in the heating mode.

On electric heat, does the same apply? If heat pump is present, do I use emergency heat to test furnace or push thermostat to regular heat?

Originally Posted by Gary Winfield

On electric heat, does the same apply? If heat pump is present, do I use emergency heat to test furnace or push thermostat to regular heat?

You really need to bone up on HVAC but the basic setup is that the heat pump thermostat is a two stage unit bringing on the heat pump as the first stage and the gas or electric heat as the second stage automatically when the temperature is 2-4 degrees below the set point. The emergency switch just locks out the first stage so that the outdoor unit is shut down in case there is a need (like and ice storm that covers the outdoor unit or it is broken) so that you still have heat from the second stage.

Jim,

I agree. As i said in my original post heat & air is not my specialty. It makes sense now that you explained it the way you did.

Thanks for your help.

One more twist to this madness.

Consider the fact that the emergency heat is actually just electric and the main heat is gas fired and there is a heat pump installed just for the tax credits to the builder. That actual happened for a period of time. I seriously doubt that the emergency heat would be the heat pump unless you had a third back up (impossible to wire for) as electric heating coils.

Think about that. If the back up was the heat pump for the heat and the temp was in the low thirties or less that would mean that you will not have any heat because the heat pump will not give you any.

Check the heat out and see if it is actually gas fired. It kind of sounds like you did not follow thru with the heat/air check out. Did you actually check the heat and the gas fired up? Or did you just turn the heat on and got heat (which I doubt because it is still summer) or was it just air blowing thru already hot ducts but was not in the low hundreds for supply temp. (unless the attic or where ever the unit ewas is already in the low hundreds)

Just some things to think about.

Again.....a heat pump for back up? when you get no heat in the low thirties or less????? with a heat pump.

I seriously doubt (least I have never seen it) that you would have gas, a heat pump and electric heat coils all in one system.

Originally Posted by Ted Menelly

One more twist to this madness.

Consider the fact that the emergency heat is actually just electric and the main heat is gas fired and there is a heat pump installed just for the tax credits to the builder. That actual happened for a period of time. I seriously doubt that the emergency heat would be the heat pump unless you had a third back up (impossible to wire for) as electric heating coils.

Think about that. If the back up was the heat pump for the heat and the temp was in the low thirties or less that would mean that you will not have any heat because the heat pump will not give you any.

Check the heat out and see if it is actually gas fired. It kind of sounds like you did not follow thru with the heat/air check out. Did you actually check the heat and the gas fired up? Or did you just turn the heat on and got heat (which I doubt because it is still summer) or was it just air blowing thru already hot ducts but was not in the low hundreds for supply temp. (unless the attic or where ever the unit ewas is already in the low hundreds)

Just some things to think about.

Again.....a heat pump for back up? when you get no heat in the low thirties or less????? with a heat pump.

I seriously doubt (least I have never seen it) that you would have gas, a heat pump and electric heat coils all in one system.

Ted, you just like trying to confuse the issue, don't you?