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

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 RV
2. So, since the roof AC/HP is 120 ONLY, you have no problem
3. 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

Hi Doug

Thanks for the reply. I will give the "auto" fan a try, it was set on high.

I DO have 120ac available Via Inverter, but turn off the inverter at night due to the inherent battery draw of the inverter, so the furnace ALWAYS sees 120ac if I have the inverter ON.

I don't want the HP kicking on when it sees 120ac coming from the inverter, and its not as simple as shutting off the AC breaker.

Your observation is correct about my lack of knowledge on the system. I am on my first shakeout after purchasing THIS particular Rig, looking for some help.

I came from rigs without heat pumps. Furnaces ran just fine on DC alone and was in no way connected to the unit on the roof. I just want to break any heating connection from the heat pump on the roof and the propane furnace, right now, the 2 ACT like they are DEPENDANT on each other.

The Serial # on the stat is 3313195.012, which does NOT have the option for a HEATSTRIP or HEATPUMP like the 3313194015's.

So it looks like the rig I bought had the AC replaced with the heatpump option, but they never installed the new thermostat to control the heat pump option but who knows, my knowledge is limited about this system.

This could be as simple as using the correct thermostat for the options installed, or setting the fan to "auto" on my current stat....

Thanks for your time, Doug. I do appreciate it

DustyRooster wrote:
Hi Doug

Thanks for the reply. I will give the "auto" fan a try, it was set on high.

I DO have 120ac available Via Inverter, but turn off the inverter at night due to the inherent battery draw of the inverter, so the furnace ALWAYS sees 120ac if I have the inverter ON.

I don't want the HP kicking on when it sees 120ac coming from the inverter, and its not as simple as shutting off the AC breaker.

Your observation is correct about my lack of knowledge on the system. I am on my first shakeout after purchasing THIS particular Rig, looking for some help.

I came from rigs without heat pumps. Furnaces ran just fine on DC alone and was in no way connected to the unit on the roof. I just want to break any heating connection from the heat pump on the roof and the propane furnace, right now, the 2 ACT like they are DEPENDANT on each other.

The Serial # on the stat is 3313195.012, which does NOT have the option for a HEATSTRIP or HEATPUMP like the 3313194015's.

So it looks like the rig I bought had the AC replaced with the heatpump option, but they never installed the new thermostat to control the heat pump option but who knows, my knowledge is limited about this system.

This could be as simple as using the correct thermostat for the options installed....which what was recommended.

Thanks for your time, Doug. I do appreciate it

Generally inverters aren't set up to power everything...or as you have seen, dead house batteries are common. Usually they are set up to only provide power to the devices you purposely want to run off the inverter.

Another thing to check is make sure the battery charger (aka: converter) isn't operating off the inverter.

Given your statements, it's probably time to call in someone with a bit of electrical knowledge.

yep, I suppose you are right. call in the pros.

FYI, the converter/charger is not working off the inverter.

I have a Victron Multiplus inverter/charger to charge the battery bank. So I have my whole rig, everything, tied to the inverter. The factory converter no longer exists.

Ill consider this topic closed. I think I have enough info to get this going they way I need to now.

Thanks for the comments

Bingo. You have the wrong Tstat. You need the CT tstat that can control HP/Heat Strip AND furnace. The furnace is seperate from the roof unit. The furnace is completely 12 volt. Doug

This is what you need. Doug

https://www.dyersonline.com/dometic-black-single-zone-fan-cool-furnace-hp-lcd-thermostat-control-kit.html

Our inverter/charger powers everything in our RV as I wanted.
We have a heat pump on our middle A/C unit and I added soft start (we like to boondock). Our thermostat for that heat pump unit has settings for A/C, heat pump and gas heat. And only one of the three can run at any given time.