Good morning, All!I have a question I am hoping one of you can help with.Purchased a 2015 coachmen class C and unknowingly it has a heat pump integrated with the AC.This would be good news, if I used campgrounds often. I boondock quite often, and when the heating circuit sees AC the heatpump wants to run in conjunction with the furnace, as those with heat pumps already know. This is not a good situation when on batteries. The 12v furnace is easily useable all night vs a heat pump firing up and taking the battery down to almost nothing its first run.How do I disable that "feature" to stop the heat pump from firing when I only want the furnace? Is there a way?I tried to shut off the breaker of the AC. That does allow the furnace to work without the heatpump, but I have to CRANK UP the thermostat in order to get the propane furnace to fire, and It does not have the 1/2 degree or 1 degree to kick on the furnace alone. So it's like the system "needs" the heat pump for operation.Any way around this?Appreciate any input!

Are you sure you have a heat pump vs heating strip in the A/C?

No, I am not sure. But it sounds like an AC compressor kicks on when heat is called. So I assumed it was a heat pump since its "basically" the same as AC except in reverse.Ok, so If I have a heating strip OR heat pump. Can I disable one of them so only the propane furnace works? I only have one of those small Dometic thermostats that has no options except to call "Fan/Cool/Furnace" and a setpoint for temp. No current temp in room/fan speed etc.

Ok-Received a response via Email. Sounds like all I need is a dual heat thermostat and I am good to go.If this is not the experience some of you have had, or there is another way to shut off the heat pump portion, please let me know.Otherwise I'll just get a dual mode thermostat ordered per the recommendation.Thanks @wanderingal for the advice!-DR

1. Boondocking usually means NO 120 to RV2. So, since the roof AC/HP is 120 ONLY, you have no problem3. Can you post pic of wall tstat? I have NEVER seen nor heard of your type problem. ALL RV HP, the furnace can be utilized without worrying about the HP coming on, including Dometic. INCLUDING if it is a HEAT Strip instead of a HP. The Heat Strip is also 120 volt. 4. IF NO PIC, can you supply P/N of wall tstat? 5. I think you have a lack of knowledge on your system. Do you have any manuals for your System? Doug(44 years as an RV TECH)Is this your tstat? Does it have 3 wires going to it?https://www.etrailer.com/Accessories-and-Parts/Dometic/DMC79FR.html?feed=npn&utm_source=google&utm_medium=cpc&utm_campaign=Google%20%7C%20Shop%20-%20Accessories%20and%20Parts&adgroupid=86797745500&campaignid=1672411894&creative=404001588944&device=c&devicemodel=&feeditemid=&keyword=&loc_interest_ms=&loc_physical_ms=9027230&matchtype=&network=g&placement=&position=&gclid=EAIaIQobChMI8vb_vOnKgAMVBkl_AB0a1wZ8EAQYASABEgKDZfD_BwE

IF you have the tstat I posted link too. IF you have Fan speed set to Hi or Lo, then IF you have 120 available the roof AC fan will come on. to STOP that you set the Fan speed to AUTO and when on furnace the roof AC fan will NOT run. Doug

Disable Dometic Heat pump on AC unit? (for dry camping)

wa8yxm
Explorer III
Aug 07, 2023
Ok I'm going to tell you what I did on my RV... First. new the Q!@$!#@$E Furnace control was flakey.. The Front Carrier A/C (I won't bother to tell you to avoid Carrier as they don't make 'em any more for RV's) controlled the Furnace and the Thermostat was part of the A/C Ceiling uint.. Had to use a fan to tame it (Blow air from elsewhere in the RV)

So I found where the wires ran down the wall (Behind the master control panel logically) and tapped them.... Did not get around to the rest till the Carrier turned into a Coleman without furnace control

Then I got a simple mercury free mechanical Thermostat from Ace hardware (NO special recommendaton other than i think it was 20 bucks or less) This type uses a bi-metal spring and magnetic contacts (the magnets make it "Snap" open or closed) and wall mounted it.. Unlike the old no longer made Mercury bulb T-Stats this one need not be level. The one I had was heat only.

Add it with a SPDT toggle switch so you can control the furnace either with the Heat Pump system. or independent and you are golden.
DustyRooster
Explorer
Aug 08, 2023
dougrainer wrote:
IF you have the tstat I posted link too. IF you have Fan speed set to Hi or Lo, then IF you have 120 available the roof AC fan will come on. to STOP that you set the Fan speed to AUTO and when on furnace the roof AC fan will NOT run. Doug

@dougrainer

This suggestion looks to have worked! Per previous post, the fan was set on "high", and it called the HP for heat assist. Per your suggestion, when I set the fan to "auto", only the propane furnace was called.

This is the exact behavior I was looking for, and it was just a tstat setting!

These forums come through yet again!

Thanks @dougrainer for the solution, and all for the feedback/suggestions.

-DR

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Disable Dometic Heat pump on AC unit? (for dry camping)

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