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Old 11-19-2021, 09:11 AM   #1
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Are 2 a/c units adequate for 40' RV

Will 2 a/c units on 40' coach keep it cool enough in 90+ heat? John
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Old 11-19-2021, 09:19 AM   #2
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No. You will 3, unless you are willing to accept the heat inside creeping upwards
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Old 11-19-2021, 09:23 AM   #3
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Nope, add a third AC unit you will not be disappointed. It was one of the smartest things we did when ordering our rig.
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Old 11-19-2021, 09:25 AM   #4
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As a service manager I was in several coaches a day in the summertime. It is unbelievable the difference in temps in coaches. Some are heavily insulated and some are not so much. Our lot was open, so all the coaches were getting the same amount of sun.
The answer to your question is maybe. The best thing to do is decide on a coach and ask the owners of that coach to give their advice.
Be careful, take advice from people that own the coach you are interested in. There are people that “just know” one way or the other.
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Old 11-19-2021, 09:26 AM   #5
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We have a 38' motorhome with 2-15k A/C units and any temps above 90 to 95 will see a gradual rise in indoor temps throughout the day. We try to start extra cool in the morning, keep the sun out with shades and parking in sites with morning sun rather than afternoon sun.

Temperatures in the high 90s will see inside temps of ~78 with the A/C set at 72.

Our coach has dual pane windows and is moderately insulated. The windows and the sun direction in the afternoon make the most difference.
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Old 11-19-2021, 09:36 AM   #6
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I've had a 40' with 2 AC's (poorly insulated) and now a 44' with 3 AC's with incredible insulation. So first off make sure you choose a good quality coach builder if you are set on a 40' un it with only 2 AC's. But lastly I personally would NOT buy a 40' coach with only 2 cooling units regardless. We just do too much summer camping in the heartland with high temps & humidity to worry about it. We only use the 3rd AC maybe 20% of the time but I wouldn't be without it.
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Old 11-19-2021, 09:37 AM   #7
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My experience with my coach below listed,,,,, no.

I assume at 40' it is a diesel pusher? If yes at the end of a road day you will have a very warm back 1/3 of the coach. Takes many hours for the engine to stop heating the rear floor. Our rear air runs a lot more then the other units when we shut down at the end of a day. Could make for some uncortable sleeping.

I also enjoy that we can cool the coach in about 15-20 mins with all 3 units running,

Our coach has the 3 a/c unit option,,, which besides a third unit includes a 10k genny so you can run all 3. It is not a inexpensive option.

Something that works for us,,,,,, while traveling,,,,, when our 2 front slides are in and we are driving, the end walls are about 3' apart. Purchased a spring loaded curtin rod and wife sewed up a curtain to hang between there. It isolates the cockpit area, the dash a/c,,, or dash heat now does a pretty good job keeping that area comfy as we travel without the genny and roof air or furnaces on.

As others said, my experience with my 2 coachs we have owned, latest with 3 units.
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Old 11-19-2021, 09:49 AM   #8
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Does anyone still make rigs with basement AC/heat pumps?

I just love ours. No AC units on the roof, and nice even heat/cool from the ceiling outlets throughout the rig.

As far as 3 vs 2 roof units, the old adage of "More is Better" kicks in. 90% of the time 2 will be fine, but on those smoking hot days you may regret not having that 3rd unit.
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Old 11-19-2021, 09:58 AM   #9
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We have a 40' MH that sits on our lot facing into the afternoon sun. Its windshield is covered by a exterior sun shade which provides protection but it's still a large heat load.

Previously we had a pair of year old 13,500 BTU Dpmetic Penguin A/C's and they struggled in the afternoon. We now have 15,000 BTU Coleman/Airexcel heat pumps and they go through the hottest summer days without any issues. The coach is so well insulated that the rear unit rarely needs to run and I turn its fan on "continuous" so it can help out the front unit more during the afternoon and early evening.
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Old 11-19-2021, 10:29 AM   #10
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Depending on how well it is insulated and where you spend the summers, I would prefer to have three units on a 40' coach. the front caps and front windshield are huge solar gains on a motorhome.

We have a well-insulated (dual pane windows) HitchHiker Champagne and do well in 100 degF plus weather with two Coleman 15 kBTUH heat pumps.

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Old 11-19-2021, 10:43 AM   #11
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Depends on the coach. we have a older 41'Beaver Marquis with two ducted (distributed) 15000 BTU Penguins that do great in 90 to 100 heat. 75 is our preferred inside temp in the summer. In fact the Bedroom can become a "refrigerator" since its a small area with several supply ducts.
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Old 11-19-2021, 10:44 AM   #12
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I can tell you from personal experience with our 42' Mountain Aire that 2 ac worked OK. But they work awesome now since I had the windows done with ceramic tint.

The ceramic tint not only keeps the UV rays out but around 97% of the heat.
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Old 11-19-2021, 10:58 AM   #13
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At first thought, a 13.5 or 15k btu unit works fine on just about any 20 foot RV. Since this is the case, you'd think that two units would do alright if the square footage was simply doubled.

What would bite a person in the behind is not adding in the square footage created when slides were extended. The number and size of slides will make a big difference. A newer 40 footer today probably has at least two, if not more slides, and would probably need that third unit to cover 90° plus outside temperatures.

Edited to add: Having a third might save a trip if one of the units decided to take a dump.
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Old 11-19-2021, 11:30 AM   #14
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You might also want to look into one of the reflective roof coatings that claim to reduce the amount of thermal heat through the roof.
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