Heat Pump question

[Derby6]

Initially posted on another thread vice starting new thread, but it was in practice forums and felt I would get more visibility here.


I have heat pump question(s). When mine is on, It seems to be producing some heat (I can feel warm vent) but air flow is minimal and what air flow there is doesn't seem warm/hot (wife says air movement makes her cold). Think I may be using the vents wrong.

For Heat pump on rear unit I select Mode=Heat // Source=Electric // Fan=Auto
Should I have Vent open or closed?
Should I have Vent fan on or off?

Lastly will that rear unit push air all the way to front ducts in bedroom?

Current temps in 40/50's at night so if I could make this work vice burning propane that would be awesome!!!

[Camp CA]

Good question for your dealer. My 2020 Montana has one heat pump in the living area and I simply press the thermostat mode to heat pump and set the temperature..........no vents to open or close. Heats the trailer quietly and comfortably in combination with the electric fireplace.

[M&M]

Your settings look appropriate for those temps and the rear HP should do the job. With proper airflow it will push heat to the bedroom in that model. A few things to check to improve airflow 1) remove each of the supply vents and use foil tape to seal so all air is going into the conditioned space and not leaking from around the vent to the attic. 2) Remove return air grill and see if it is fully open to the duct. You need complete openings to return air to the unit for air not to be restricted. I found the opening cut in the ceiling was 10-15% smaller than the grill. That means you’ll get that much less airflow. If not cut opening same as grill and foil tape to improve. There are other recommendations to improve airflow but I found these to be the easiest and provided noticeable improvement.

[Daryles]

As you probably already know, the heat pump in these units doesn't work below about 40⁰F.
Newer home units will work down to 30⁰F.
Check your return air vents (and all the vents) to be sure they are sealed correctly
See post #4 https://www.montanaowners.com/forums...ighlight=Ducts

[Derby6]

Ok I am thinking my vent should be open, fan on low or high.
But then option appears of in or out for vent. I think that should be out for heat???

[Foldbak]

The Coleman 2022 heat pump is ducted throughout the trailer. Setting the rear thermostat on electric heat, auto fan should start the unit and heat the rig. The front won't be as warm due to the distance the air has to travel. I'm not sure what vents you're referring to. Combined with your fireplace and ceiling fan you should have plenty of warm air flow.

[Daryles]

Can you post a picture of your thermostat and year of your rig?
I have a 2019 with a Dometic capacitive touch (CT) thermostat.
For mine to operate correctly I leave the fan in "Auto" then select the function, Furnace, Heat Pump, Air Conditioning with the mode button.
I do not have a "vent" function on the thermostat.

[Derby6]

I have no thermostat; unit is a 2022 3231CK and I have In Command system.

Was gone for better part of day and I had vent open and IN; seemed to be OK, but I think I'm supposed to have vent open and OUT for heat. Will see as it cools off this evening!

[M&M]

On my 2021 unit I found the vent options were not connected to anything. I removed those options from the display.

The green and yellow wires in the hp control box labeled Maxxfan have nothing connected to them.

[Derby6]

Thanks--That's interesting. I kinda wondered why when I would change options I would not hear anything move/notice a change. Except maybe vent fan speed???

[Daryles]

Derby, sorry I don't have In Command.
I do recall reading a post regarding it.
There was very specific instructions regarding the operation.
Maybe do a search on "In Command" or someone my be familiar with that?

[DutchmenSport]

I didn't read all the posts, but when the outside temperature reached about 45 degrees, heat pumps don't blow heat any more. They only blow cold air. They work very well when temps are above 45. It's just the basic nature of an RV heat pump design. Nothing you can do to make this better.

I suggest you pick up a couple ceramic space heaters to supplement the heat when temps fall below 45 to the point they can't keep up any more either because the ambient temperature is simply too cold and the camper has simply too much space. Space heaters do help off-set propane usage a lot too.

[Cat320]

Originally Posted by DutchmenSport

I didn't read all the posts, but when the outside temperature reached about 45 degrees, heat pumps don't blow heat any more. They only blow cold air. They work very well when temps are above 45. It's just the basic nature of an RV heat pump design. Nothing you can do to make this better.

I suggest you pick up a couple ceramic space heaters to supplement the heat when temps fall below 45 to the point they can't keep up any more either because the ambient temperature is simply too cold and the camper has simply too much space. Space heaters do help off-set propane usage a lot too.

Agree. I have a HP and never use it. As a substitute I have two Lasko tower heaters, they are small, light, portable, have adjustable thermostats, Low/High power settings, oscillation capability, and durable...one is over 10 years old.

[bshgto]

85°F to 92°F
The average temperature output of a heat pump is 85°F to 92°F in heat mode without auxiliary heat. Typically, a heat pump will produce a temperature differential of 15-20°F warmer than the current air temperature in heat mode. The air temperature from a heat pump can vary with the age and condition of your heat pump.
So with that being said even under the best conditions the air temp coming out of the vents is below body temp. This is why your wife fells cold. But that`s at the vent not at 4.5 ft. too 5 ft. off the floor where your heart is. And with a 10 ft. ceiling it`s even worse. Rv a/c`s efficiency rating is terrible. just plain sucks
My rear heat pump- a/c unit stopped working this fall and now won`t put out cold or warm air. So it needs to be replaced as I have determined that the reversing valve is stuck mid-way in it's travels. And the new ones are 1800.00 dollars maybe a little cheaper some places plus installation I was going to put in the 3rd a/c but not now.
So I`m putting in a Mini split system. Less than one 3rd the cost of 2 new units half the noise, the heat pump works down to 10 degrees, draws less amps (for the generator) and I will mount the head over the tv in a 3791. The bonus is any a/c tech can work on it. Not just replace it. It will cool or heat the whole first floor like nobody's business. I have talked to 2 different people that have done this in a 3791 they mounted the small outdoor unit on a fold down tray in the back with flexible refrigerant lines to access the roil out tray. Both said the rv a/c dose not compare.
Good winter project.......we`ll see.

https://www.youtube.com/watch?v=TP0KxDykO6k

[mlh]

It’s 40 degrees here and my mini split is putting out 109 degree air and if needed it will put out 120 degree air.
I can’t think of a reason the camper manufacturers don’t use mini splits. They will heat down to -20 degrees or lower.
Lynwood

[Derby6]

Been meaning to post this and got busy. Posting what I figured out with above help, research, and trial and error. Now I have place to go if I need a reminder and hopefully helps others out in the future.

As M&M stated the bottom bottom Vent controls do nothing.
And as DutchmenSport pointed out, the heat pump only work to about 45 degrees.

If I have heat source set on GAS and fan on auto, BOTH the furnace and the heat pump run. I will use this setting when low temps are 45-55.

If I heat source set on ELECTRIC and fan on auto, BOTH the furnace and the heat pump still run. However, the heat pump is the primary; the furnace only turns on when it is needed due to temperature drop well below set temperature; seems like about 10 degrees. I will use this setting when low temps are about 55 or higher.


If I heat source set on GAS and fan on off, ONLY the furnace runs. I will use this setting when low temps are below 45.

[M&M]

You nailed it and agree with you conclusion. On my unit the temperature difference on auto is 3 degrees under will start the furnace. So what I do if trying to warm up with just the heat pump, is step it up 2 degrees at a time.

[TripleP]

I have a 2021 Montana 3761 FL. Am I to understand that my rear AC that is in my bedroom is the one with the heat pump? I was under the assumption it was the middle AC in the kitchen. Unfortunately my rig is in storage and I can't check at this time. Thanks

[Foldbak]

If I'm not mistaken the kitchen AC is an option so that would lead me to believe the heat pump is in the front. I don't think they would put it in the bedroom.

[Mikendebbie]

I agree with Tony - the front unit is the heat pump.

Edit: this opinion is based on the heat pump in my RV serving the larger space.