Ductless AC instead of roof mounted AC

[lastword]

In addition to my roof repairs I am replacing the AC unit on my trailer.
Does anyone have any experience with the Mini Split Ductless AC Heat Pump reliability on an RV? I have seen installs on youtube and they all claim no problems with it. I worry about the bouncing going down the road causing a freon leak, But when I look at the construction of both roof and ductless I don't see significant difference in the build quality or design. So I'm thinking there should be no problem.
Planning to mount the outdoor unit and a generator to a welded platform on the rear of the camper and install a small brush guard and backup camera, and make sure the line-set is insulated and supported properly.
The unit I am planning to use ($460.00 delivered).

https://www.ebay.com/itm/12000-BTU-15-SEER-110V-Mini-Split-Confort-System-Ductless-AC-Heat-Pump-110V/303081116734

Says its good to 600 square ft, I have a little over 200, heating and cooling.
I have worked in manufacturing and installed and maintained many AC units. I have all the tools vacuum pump and hoses/gauges.

Thoughts? Sanity Check!

[S_Davis]

Be careful messing around with the fittings while the unit is running, R410a systems can have operating pressures above 450psi.

[Gulfcoast]

I've used the copper washers mentioned above, and never a leak again in over 20-years.

[mobeewan]

As far as leaking flared joints, 45 degree conical copper washers have been used for years to seal between leaking 45 degree fittings. Several years ago an a/c auto shop installed 2 in the a/c lines in a vehicle I owned to stop leaks at the 45 degree joints. I and the next owner who is a friend never had another a/c leak.

[seaeagle2]

The torque values should be in the installation manual. Those flare fittings are the weak point at this time. There is a whole industry trying to produce an easy to use, reliable tool that will consistently produce a non leaking flare. If it was leaking, and you just tightened it down, it's probably going to leak again at some point.....

[CavemanCharlie]

Thank you for the update.

[ajriding]

Photos photos photos otherwise this does not make as much sense.

Glad it all worked. I did a lot of research on alternatives to the roof unit.

For the amount you spent on this device, why did you not just put on a roof AC and be done with it? A roof unit is built for the road and you are experimenting as if a house unit will hold up over the years of driving…
Ebay finds are maybe $600-800 or a used one around 400. Hint, I have a used Penguin that is perfect in every way except wont run off a 2200 gen.

[Planning]

lastword wrote:
Mini split Update

Overall I am quite happy with the performance of the Mini split

Would love to see a photographic overview of the installation.

[wiskeyVI]

I've seen folks use mini splits I "tiny homes" and converted cargo trailers with good results

[jplante4]

Could you put up a couple of pics of the installation?

[lastword]

Mini split Update
Installed 4/17/2019 so 4 months later its still running and working great. We have taken 4 camping trips 45min, 50min, 1h20min, 2hr30min drive from the house each 4 day duration. I was worried that road vibrations would cause R410a leaks, but none to date.
I have kept it plugged in and running at home since 4/17 set on 82f unless I go in to work on the interior basically as a dehumidifier and to gain a little confidence on reliability.
I did have a problem with a leak at initial installation and had to charge it after finding and re-tightening the leaking flare connection. The high pressure line at the air handling part was leaking. I could not find a torque value for tightening the connections which could be helpful in avoiding this type of leak. I used a bar of soap with a few drips of water and a paint brush to find the leak.

The unit uses .75A with just the blower running and 5.42A while cooling. The unit has no problem holding the camper at 66F while 96F outside. I am quite impressed with its ability to cool. I will report back this winter when I am able to test the heating part of the unit. There are no electric heat strips installed.

Overall I am quite happy with the performance of the Mini split

[DrewE]

lastword wrote:
I will stay with 120v at 7amps.

I'm also looking at making a relay that will hold the compressor off when the refrigerator or microwave is starting. Something that monitors the amp draw/power coming into the RV. When a threshold of amps is drawn by something the control circuit/wire to the compressor is held open (compressor off or wont start). Make the threshold settable.

Assumed usage:
Microwave 5 amps
Refrigerator 3.5 amps
Ductless ac 7 amps
so about 15.5 amps when all is running and assume 2x when it tries to start

As long as more than one thing does not start within a few seconds of each other all is swell!!

Thoughts?

The microwave will use more power than that; the oven's wattage rating is output power, and AC power consumption is at least a couple hundred watts more. Most these days are at least 900W or so output, so 10+ A. There's no appreciable extra startup surge for a microwave.

3A for an RV fridge is about right (and again no startup surge). A residential fridge uses a lot less running (1A or less) but more when starting up or defrosting.

The starting power for the mini-split air conditioner might not be much if any more than the running power, since the units typically use a variable frequency inverter motor drive circuit. It definitely ought to be much less, relatively speaking, than a standard RV air conditioner.

Don't forget the converter or inverter/charger, which if the batteries are low can be consuming several amps as well.

I would not worry too much about automatic load management for a 30A power source. Many 30A RVs (mine included) have an air conditioner and a microwave, and many people (myself included) use them simultaneously without trouble if there are no other major loads. For a 15A connection, probably just turning the thermostat off before microwaving would do the trick and not need anything in the way of fancy wiring.

[The_ugly_duckli]

I have a 12,000BTU, 110V Mini Split air/heat pump in my cottage. It's 750 sf and moderately insulated. The 12,000 btu is more than big enough for our application. I bet it will easily cool your camper, even though it is not well insulated. The beauty of the Mini Split is it's VERY quiet. Your more likely to keep it running all the time when it's hot because you forget it's on. I know the noise of my roof top unit drives me nuts after a while and I find it difficult getting to sleep with it cranking away.

I've also explored the idea for my camper, but alas I just can't find a place to fit it. 😞 Good luck with your idea!

[lastword]

Gulfcoast wrote:
I think a 115 volt mini-split is a great idea, but here's my question.
My 13,500 rooftop unit will not cool our 200 sf trailer at 90-degrees outside.
Will a 12,000 btu mini-split keep it comfortable? I'd hate to do all that work and still be hot.

You bring up a good point.
The roof ac coming off this Terry EXPO 24LZ (147 square ft) is a 13,500BTU unit too. The unit was DOA when I got the trailer and the previous owner said it did an ok job (hard to quantify).
The rub is above 12k BTU the units are all 220V.
That is why I questioned earlier about campsites with only 110v 30A available.
I have a 220v 30amp generator but don't want to run it in a campsite with shore power. The neighbors probably wouldn't like the noise either.
The Ductless mfg says it can cool 400 to 600 sq ft or about 2.7x to 4x the size of my camper.
The next step up is 18k BTU 220VAC

I'm currently replacing the roof and plan to replace the R6 insulation with R32. This should help some. I am also enclosing the bottom of the trailer with Corex material (the same stuff the political signs are made from, only thicker)purchased in 4x8 sheets. I would like to insulate too but am worried that it might hold water.I might try the bubble wrap stuff (r values are pretty low).

The sides of the trailer are insulated with 1/2 inch thick foam about R3.25, cant do much about this.

[Gulfcoast]

I think a 115 volt mini-split is a great idea, but here's my question.

My 13,500 rooftop unit (one year old) will not cool our 200 sf trailer at 90-degrees outside, in the sun.

Will a 12,000 btu mini-split keep it comfortable? I'd hate to do all that work and still be hot.