RV AC/heat pump

[littleboss]

Looking for input on the rooftop inverter type AC/heat pump.

If you have one how do you like it?
How quiet is it?
How cold will it still produce heat?

Thanks

[Camp CA]

We have a rooftop AC/heat pump and like it, Its relatively quiet and heats the rv down to ~40 F outside temperature.

[wildtoad]

My last mh had an hp, not sure what type, and we used it all the time. As above works well for heat as long as outside temp is 40 or above, not so well under 40. I like the fact when it knows it can’t heat it auto switched over to the furnace.

It’s no noisier that a std ac unit except for when it goes into defrost mode but even then not too bad.

[Mike8253]

Our front roof unit is both AC and Heat Pump. We use it 1st in preference over the furnace, and it's effective down to around 40 degrees. Sound is same as when in AC mode, so not obtrusive during waking hours. And the nice thing about it being in the fwd. location is that there is only minimal noise in our bedroom when running at night; and we can manage the ducting in the ceiling to direct a greater % of the heated airflow to the bedroom at night. Certainly reduces the propane consumption as well.

[d23haynes57]

I have old school rooftop heat pumps. They work really well to just below freezing. Under 20F they struggle to get started, lots of humming and the heat is not much. Near freezing and above they make a lot of heat, much more than the Hydronic. You do hear them just the AC and they blow the hot air on you.

[Jkwilson1989]

Is there such a thing? As far as I know, the Furrion Chill Cube is the only rooftop inverter style AC on the market, and it isn’t a heat pump.

[littleboss]

This one say good to 33 degrees

https://ecocool.premierproducts.net/products/fb-black

[Dutch Star Don]

Heat pumps are basically your AC running in reverse. So, the heat pump will make the same amount of noise as your air conditioning. The temps it will work in has been discussed above.

We liked to use them in a previous coach when we had hookups, as it saved using our propane, versus the campground's electricity.

Since they heat at the roof line, they can leave the floor level cold. When you stand up from a chair or couch, it's will be like sticking your head into a heat pocket.

When we used ours, we had two, one in the bedroom and one in the main living area. When in the main living area, we turned the rear unit on high to keep the noise down up front and still heat the main area. When we went to bed, we reversed that, running the front unit and leaving the rear off.

Because of the noise, we more often used a couple of portable heaters in the coach.

Just our experience in a Monaco Diplomat!

[photopilot]

As Don says, we run a portable heater in the bedroom if it’s really cold, otherwise we just run the front heat pump. I highly recommend the Wacko Products RV A/C Silencer to reduce the noise. Www.wackoproducts.com.
(Just a satisfied customer)

Walt

[littleboss]

Having a heat pump in the ceiling is no different than most houses having the vents for the furnace in the ceiling. If your feet are cold then the floor isn't insulated properly.

So far I have found that the only actual inverter heat pump (like a mini split) is the Turbro Greenland 13,500 BTU Model GL14V. Says it heats down to 19 degrees and has adjustable heat output from 7200-13500 btu's as it ramps up and down.

The ECO-COOL and TSOT are the same unit made by GREE. Not a true inverter heat pump.
The REC PRO heat pump is made by Houghton and isn't a true inverter either.

I will probably go with the Turbro and use supplemental heat if necessary

[Melungeon]

By their design, heat pumps can only produce the same amount (BTUs) of heat as they do cooling. Larger RVs are normally equipped with 35-40K BTU furnaces while the max you'll ever get from a roof top heat pump is 15K BTU. Heat pumps are much more efficient in maintaining a set temperature than they are at overcoming a large differential temperature. Outdoor temps permitting, do the initial warm up with the furnace, then switch to heat pump.

As mentioned before, a heat pump has a reversing valve that reverses the refrigerant flow. The blower has to run the same speed as on AC to help keep the coil from freezing. The noise levels will be the exact same in both modes.

Having the heat vents in the ceiling isn't the ideal situation in heating mode, especially in an RV. The returns are ceiling mounted also and it's much easier to create an air short circuit where the warm discharge air stays closer to the ceiling and is pulled back in by the return rather than warming the space.

Many of the AC manufacturers offer an electric heat strip which is mostly a joke. You're limited to 1.5KW to be able to run on a 20 amp circuit. That's only a little more than 5000 BTUs of heat and you can't run the heat pump and heat strip at the same time. Even with the limitations, I still believe it's a good economical way to supplement the gas furnace or primary source in milder conditions.

The Furrion Chill Cube is Furrion by label only; it's an LG variable speed mini split in a Furrion housing. LG is one of the premier manufacturers of residential mini splits and a very high qualiity product. The variable speed units always start on a very low speed and speed up over a few seconds, there's no inrush current. They also go to a very low speed once temperature set point is reached and will continue to remove humidity. It's an 18K BTU unit; they don't make a heat pump version yet, but I'm sure it's forthcoming.

Another new variable speed unit is the Turbro Greenland, it is a heat pump and for now only in non-ducted. I'll link a video, this guy is an engineer and does extensive measurements on performance and noise.

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

[SafariBen]

Originally Posted by Melungeon

By their design, heat pumps can only produce the same amount (BTUs) of heat as they do cooling.

Generally, that's not true. The cooling is not helped by the heat off the motors. Theoretically, all of the heat running the compressor and fan motors can be added to the "pumped" heat, but that is not always the case with reversing heat pumps.



Most houses in the north have heat registers in the floor, and cold air returns in the floor also, so the coldest air is returned to the furnace. Not so great for A/C, but works much better than ceiling registers for heat. If you have air leakage, then insulation in the floor is irrelevant, the fan has to work hard to mix cold air coming in at floor level with hot air up high. RV's just aren't designed well for heating.

[Tim_T]

We have a Houghton Belaire 3400 AC/heat pump in our host cascade truck camper. It runs on AC only, but I could power it with the inverter in the camper until the batteries ran out.

I think it is a 13.5k BTU unit. But the volume in the camper is probably equivalent to an 18 foot trailer.

A few weeks ago I tried to run it in the low 20's, wouldn't start and displayed something I interpreted as "too cold to run".
I have successfully run it in the upper 20's while prepping for the current trip. At about 30F outside with the thermostat set to 60, it was cycling on and off holding temperature.

Last night, at about 40F, we were at a comfortable 65 inside, but probably could have increased the setting.

Tonight we will burn propane because we are in the mammoth cave NP primative CG.

[Melungeon]

Originally Posted by SafariBen

Generally, that's not true. The cooling is not helped by the heat off the motors. Theoretically, all of the heat running the compressor and fan motors can be added to the "pumped" heat, but that is not always the case with reversing heat pumps.



Most houses in the north have heat registers in the floor, and cold air returns in the floor also, so the coldest air is returned to the furnace. Not so great for A/C, but works much better than ceiling registers for heat. If you have air leakage, then insulation in the floor is irrelevant, the fan has to work hard to mix cold air coming in at floor level with hot air up high. RV's just aren't designed well for heating.

It's true that motors generate heat. The compressor and blower motors are NOT located in the conditioned air path. They neither add or remove heat to the conditioned air.