Lots of YouTube videos on RV AC and mini split discussions. Getting off the grid and being sustainable is certainly a challenge. Pros and cons for every system.

Most of these discussions are based on installation into or on 5th wheel units. These units more than likely have much better insulation than our '90s built Barth. My 94 30' Breakaway is awful. Below 40 degrees My furnace (35K BTU Atwood) runs virtually continuously. Over night without heat the cabin temp in the morning is below 50 degrees. As soon as the sun comes up and hits a side or top of the Breakaway inside temp starts to rise and in less than an hour it is 75 degrees, after 2 hours the inside temperature is over 80 degrees, even though outside temperature is just getting to 65 degrees.

If I am running down the road and temperature outside is over 85 degrees my roof air is on and to keep the front reasonably cool I have to close the rear bedroom door.

Until I do a complete insulation rework, I'm not thinking about HVAC systems! I have 675 AH battery system that I can dry camp for about 1-2 weeks if I watch my electrical usage. I don't have solar yet.

Check this YouTube video out, the guy has done a lot of research including some 12VDC and dual voltage units.

HTH

RV AC on solar

I totally agree on the insulation argument. My 86 Regal had full fiberglass insulation. While only 2" thick it was much better than my Monarch which had none. The single pane windows in the Regal would sweat and frost up, so I made Plexiglass inserts. Once I did that, it would stay warm with intermittent heater down to the low 20s. In the summer I could cool it with one AC.

Sometime in the early 90s Barth quit using full insulation. My Monarch was terrible in the cold and in the heat of summer. When I drove in the winter, anything below 40 degrees kept the furnace running almost constantly. In the summer sun the walls and roof got warm to the touch inside, needs both ACs to stay cool.

Fortunately, the curved roof of the Monarch allows access to the ceiling and I was able to put 1" styrofoam and some fiberglass in most of the ceiling.

Insulation thread here: https://www.barthmobile.com/eve...023966197#2023966197

Noticed some improvement in the cold but the walls still need insulation. The roof work has made a bigger difference in the AC use though. Since most of the heat from the sun is on the roof, the insulation there makes a big difference. Here in Florida I had been using AC by late morning, now I get at least 2 hours more time before I need the AC.

With the big improvement from the roof, I am very interested in getting something into the walls. If I could get something blown in there it would really help. I don't think home insulation (ie cellulose or chopped fiberglass) would be useful from the standpoints of moisture and settling from the coach moving. Styrofoam beads would be better, but they are not normally used in buildings due to fire concerns and are hard to find. I am still planning to do something eventually.

Bottom line: If we are looking for independence from the grid, insulation would be a big factor. A BIG difference in the thermal demand on both heat and AC.

Steve, look into urethane foam in place. Pretty tricky stuff
but, if handled correctly could be a good rigid insulator.

quote:

Originally posted by Dick Dubbs:
Steve, look into urethane foam in place. Pretty tricky stuff
but, if handled correctly could be a good rigid insulator.

For sure, the gold standard! I am trying to avoid the job of removing the wall panels. With all the cabinets, etc it would be a major project. As you suggest, the installation requires considerable skill and the correct equipment. Sure would be nice, though.

Steve & other Barth devotees,

Not only is it the amount of cabinets, it's the amount of fasteners anchoring them into the walls, floors, ceiling, & even the furniture. We just painted the interior walls of our Breakaway & we are thrilled with the way it looks. During the process, we attempted to remove some of the smaller cabinets. It was unreal how the assemblers (especially on 3821) anchored these components. Maybe they were being paid per fastener installed

Good Luck,

John

this is just something to think about . i recall older 1960 ?? range rovers particularly when used in Africa has a single pane of alum roof apx 1.5 inches above the regular roof . sun never hit the real roof . open all around i know there is tons of junk on a RV roof but if you double roofed 60% of it , what would the reduction of heat gain be ?
does not run the generator or the ac all of which produce more heat .

Jack, that gapped roof is probably the absolute best one can do for sun load, air is one of the best insulators, vacuum being the best. Make sure the sun can never hit the actual roof. The problem comes with the added weight and wind resistance when traveling. My bet is it will take away a 1/2 mile or more per gallon.

We have one of those gapped roof's on our newest medic unit . The ambulance company calls it a tropical roof . Basically a sheet of diamond plate across the entire ambulance box with about an inch or so air gap . It makes a world of difference on these hot southern summer days . The interior of the ambulance box is much easier to cool than without it . I was just talking to cat about this today . If we had goat rails like the Wanderlodge , it would be a fairly easy modification

Expanding urethane is a great insulator, use in refrigerators is with a $500k urethane machine very accurate volume dispensed, and still the inner and outer skins are supported with a really strong framework during the operation. Pretty sure even the most experienced application guy with a hand operated foam gun is either going to underfill or blow the panels off, do not think most installers would even give it a try. Best to remove the panels and even the cabinets, spray the foam, let it cure and shave it back for the correct fit, just like in the walls of a new house.

Blow in beads of Styrofoam can be installed in holes, electrical outlets, any opening. Not as good as foam but not much difference and for the amount of work saved by not removing panels probably the good way to go, even if it might settle a bit over the years from road vibrations.

Bally Case and Cooler company was one of the early users, experimenters, of foam in place urethane. They blew up a lot of panels before they developed reinforcing forms and exact measurements before they got into full blown (get that?) production.

I have a gapped roof sorta. Solar panel cover about 70% of the roof. This solves two problems

quote:

Originally posted by Jack Finn:
this is just something to think about . i recall older 1960 ?? range rovers particularly when used in Africa has a single pane of alum roof apx 1.5 inches above the regular roof . sun never hit the real roof . open all around i know there is tons of junk on a RV roof but if you double roofed 60% of it , what would the reduction of heat gain be ?
does not run the generator or the ac all of which produce more heat .

was looking for info on mini-split AC units for rv's and came across this thread..

what you are describing above it called a 'tropical roof'

We have a "tropical roof " on the box of one of our medic units . I believe it helps keep it cooler. It seems to stay cooler than our other medic units in this Louisiana heat .
We were told that it should drop the temperature about ten degrees compared to a similar unit without it .