AC Heat Pump units that work well below freezing?

[yoloinsc]

I was researching upgrading the front A/C unit in our 2015 3711FL to something quieter since the fan needs to be replaced in the unit anyway.

One idea was to get a new unit with a heat pump, since there currently isn't one in this RV. I saw a lot of comments here and elsewhere that some heat pumps don't work well below 40 degrees, but I came across this TOSOT AC Heat pump combo that says it operates down to 23 degrees. TOSOT 15,000 BTU RV Air Conditioner | Heating & Cooling | 8.5 EER

What are the experiences and thoughts from people here on these? Are there ac heat pump models from other manufacturers (ideally ducted) that work well for at least down to freezing?

 

[Todd & Mary]

our AC/heat pump will heat down to about 38 degrees. I wish it operated in lower temps.

 

[Bourbon County]

If you're looking for an RV heat pump that will provide useful heat down to freezing, you can look on the same aisle with the unicorns. If you can't find one there, ask Santa to bring one. What I'm trying to say is there is no such thing.

I looked at the spec sheet on the model you linked and did you happen to notice that it's only rated for 12K BTU on heating? Your furnace is likely 35-40K BTUs so it's less than half that capacity. An RV heat pump can only be supplemental heat, or used in milder temps at best. The thing they didn't state is what discharge air temperature will you have with outdoor temp at 23 degrees. Heat pump air discharge temps fall pretty drastically below 40 degrees. Once they reach the point that they can only deliver discharge temps around 80-85 degrees, you'll find the comfort level too low to be useful. If you want to do a deep dive, look up heat pump COP (coefficient of efficiency), I believe you'll find some good explanations.

There are some residential mini-splits that claim to heat even at sub zero temperatures. The Mitsubishi hyper heat models claim to heat down to -15 degrees. The residential models aren't under the same size, shape, weight, and power constraints as RV models. As far as I know, there are only 2 RV models on the market using variable speed mini-split technology. One is the Furrion Chill Cube who uses LG to make everything but the enclosure; The other is Turbro Greenland. The Furrion is AC only and the Turbro is a heat pump. There's a really good video on You tube about the Turbro. The guy is an engineer and measures every parameter AC related, not on heating. This is a Chinese built unit and from watching the video appears to be a very well engineered and built unit. They have utilized the space available to increase the coil sizes, the condenser fan appears to be dynamically balanced, the compressor is mounted on vibration dampers.

 

[yoloinsc]

our AC/heat pump will heat down to about 38 degrees. I wish it operated in lower temps.

Which make and model do you have?

There's a really good video on You tube about the Turbro.

Thanks! Do you have a link for that channel?

 

[ACKLM8]

Our only experience with heat pump is the one that came on our 2020 3121RL (Dometic A/C-Heat Pump). I've read a lot of posts about the 40-degree "barrier" but I know that in actuality that is just a temperature at which the thermal exchange efficiency drop becomes pretty noticeable. I will generally switch over to the gas furnace when ambient gets down into the high 30's. I did check the output temp of the heat pump once when we had an outdoor temp of 35 and it registered 104 degrees, which I thought was pretty respectable. Both temps measured with certified digital thermometers, so confident of readings. Interesting to know that more efficient units are coming along, but I'm curious about associated cost.

 

[pitman44]

If you're looking for an RV heat pump that will provide useful heat down to freezing, you can look on the same aisle with the unicorns. If you can't find one there, ask Santa to bring one. What I'm trying to say is there is no such thing.

I looked at the spec sheet on the model you linked and did you happen to notice that it's only rated for 12K BTU on heating? Your furnace is likely 35-40K BTUs so it's less than half that capacity. An RV heat pump can only be supplemental heat, or used in milder temps at best. The thing they didn't state is what discharge air temperature will you have with outdoor temp at 23 degrees. Heat pump air discharge temps fall pretty drastically below 40 degrees. Once they reach the point that they can only deliver discharge temps around 80-85 degrees, you'll find the comfort level too low to be useful. If you want to do a deep dive, look up heat pump COP (coefficient of efficiency), I believe you'll find some good explanations.

There are some residential mini-splits that claim to heat even at sub zero temperatures. The Mitsubishi hyper heat models claim to heat down to -15 degrees. The residential models aren't under the same size, shape, weight, and power constraints as RV models. As far as I know, there are only 2 RV models on the market using variable speed mini-split technology. One is the Furrion Chill Cube who uses LG to make everything but the enclosure; The other is Turbro Greenland. The Furrion is AC only and the Turbro is a heat pump. There's a really good video on You tube about the Turbro. The guy is an engineer and measures every parameter AC related, not on heating. This is a Chinese built unit and from watching the video appears to be a very well engineered and built unit. They have utilized the space available to increase the coil sizes, the condenser fan appears to be dynamically balanced, the compressor is mounted on vibration dampers.

That is such a great explanation. The only thing that I'd add is that installing mini-splits for many years one thing I uncovered that doesn't show up in the general info most manufacturer's supply is that there's a dramatic drop in heat output as the outdoor temperature drops. We sold a unit that would put out heat to at least -5F. However the 36,000BTUH unit would only put out 22,000BTUH at -5F. You had to dig thru the manufacturer's engineering data to find this. All the distributors sales people would say that this 3 ton unit heats to -5F. Which was accurate, but doesn't tell the whole story. RV HPs are good in sweater weather.

 

[Barkingdogg]

I have a 2 year old Recpro/ Houghton 13500 low profile 3400. We love it so much quieter than our Dometic 15000 btu thats in our living room. The heat pump was still heating when temps got to teens in Oklahoma this last winter. We dont like to let our trailer get too cold in winter. The icing is it so much quieter than any other rooftop ac we have had

 

[RMcNeal]

I have found with my heat pump, I can get down to low 20's as long as I supplement the heat with space heaters and fireplace. Essentially the same idea as my home heat pump using heat strips to supplement the heat pump. The colder it gets, the less you get out of the heat pump itself, but it does distribute the heat throughout the rig.

 

[mlh]

I would keep the unit you have. The new units have a new refrigerant in them it’s propane and butane and many of the coils are going bad. When that happens you get all that inside your camper. If you have to get a unit be sure to get one that has been sitting on the shelf with the old coolant in it.
Lynwood