Furnace vs Heat Pump

[Dog Show Gal]

Had this odd thing happen with getting heat in the RV, and this has never happened in my previous 2 RVs that had the furnace or heat pump option.

I was dry camping and it got cold so I turned on the "furnace" setting via the Dometic thermostat. Worked perfect. Later on I turned on the generator and the air conditioner/heat pump on the ceiling turned on, even though "furnace" was still my setting. First I had cold air blowing out, then it turned warm, and then when it hit 68 degrees, it blew cold air again and did not cycle off. However, I did not want to use the heat pump, I think the propane furnace works better.

I cannot find anything about this in the Dometic booklet. How do I stop the heat pump from turning on when I have furnace selected? Hope this all made sense.

[MNtraveler]

Originally Posted by Dog Show Gal

Had this odd thing happen with getting heat in the RV, and this has never happened in my previous 2 RVs that had the furnace or heat pump option.

I was dry camping and it got cold so I turned on the "furnace" setting via the Dometic thermostat. Worked perfect. Later on I turned on the generator and the air conditioner/heat pump on the ceiling turned on, even though "furnace" was still my setting. First I had cold air blowing out, then it turned warm, and then when it hit 68 degrees, it blew cold air again and did not cycle off. However, I did not want to use the heat pump, I think the propane furnace works better.

I cannot find anything about this in the Dometic booklet. How do I stop the heat pump from turning on when I have furnace selected? Hope this all made sense.

If you go to your fan setting, I'll bet it's set to LO or HI, not to AUTO. When that happens, the fan on the AC/heat pump will go on whether you call for heat or air or not. Always leave this on AUTO. The LO and HI settings are nothing but trouble.

[sgtlm17]

It sounds like your fan setting is not in auto mode but rather set to high or low. Select fan on thermostat. Then select auto. If not in auto mode when using furnace and rig
Has 120v via power cord or generator the ceiling fan will come on. Here's a video how that thermostat works.
https://youtu.be/PQumILC3yv0

[Dog Show Gal]

You are my HEROES, both of you!!!!! Thank you and the video was perfect. I just checked the RV and the fan was set to Lo. I will let you know if I have any problems next weekend when it is supposed to be very cold at night.

Originally Posted by sgtlm17

It sounds like your fan setting is not in auto mode but rather set to high or low. Select fan on thermostat. Then select auto. If not in auto mode when using furnace and rig
Has 120v via power cord or generator the ceiling fan will come on. Here's a video how that thermostat works.
https://youtu.be/PQumILC3yv0

[sgtlm17]

Your very welcome

[MNtraveler]

Glad it is resolved!

[xgarys]

I'm glad you got it taken care of. Out of curiosity, what breed(s)?

[Dog Show Gal]

Originally Posted by xgarys

I'm glad you got it taken care of. Out of curiosity, what breed(s)?

Pointers!!!

[xgarys]

Nice! We're not breeders but we favor Whippets.

[Scrapper]

One thing to point out is if your A/C is on the roof then you have an electric heat element inside it. A true heat pump is just a A/C with the compressor running in reverse and they are generally mounted in a side wall. Also a heat pump is useless below 40 degrees.

[CDRJML]

Agree. We use the heat pump to take the chill off
But use the furnace at 40 and below.

[Kirk S]

Originally Posted by Scrapper

One thing to point out is if your A/C is on the roof then you have an electric heat element inside it. A true heat pump is just a A/C with the compressor running in reverse and they are generally mounted in a side wall. Also a heat pump is useless below 40 degrees.

Interesting. My Forester 3051 with the Dometic 15k roof air is supposed to be a true heat pump without the heating element. I'll have to investigate further.

[fobagbob]

Originally Posted by Scrapper

One thing to point out is if your A/C is on the roof then you have an electric heat element inside it. A true heat pump is just a A/C with the compressor running in reverse and they are generally mounted in a side wall. Also a heat pump is useless below 40 degrees.

The AC in my old old Class C had a heat strip, the AC in my 2017 Forester is a heat pump, no heat strip. You can hear the compressor running in the heating mode and yes, it doesn't work well below 40 degrees, we use the propane furnace then.

The compressor doesn't run in reverse in heat pump mode, the valving reverses the refrigerant flow to switch the function of the condenser and evaporator coils to remove heat from the outside and expel it to the inside of the RV.

[MNtraveler]

Our Dometic AC is also a heat pump not electric heat strip and is located on the roof. True about 40 degrees, use furnace in that range or lower, or electric resistance type space heater if you prefer.

[newRVer]

Interestingly enough on a recent trip to NC I turned on the heat pump expecting the temp to go down to 43 and woke up in the middle of the night because I did not hear the fan on the Heat Pump running. (we always set it to constant Lo speed and not Au at night). It sounded almost like it had frozen up. I turned on the furnace and all was well. Later that morning I discovered the temp in our area actually went down to 37 which might explain why the heat pump stopped working. I always thought that a heat pump would just not output any warm air if the outside temp was below 40, didn't think it would stop working entirely. A few days later we used the heat pump again with no issues but it only went down to about 50.

[MNtraveler]

The coils freeze up.