Cooling a 40' Bus

[melwade]

We have a 40 (3 foot RE bus with a 21" roof raise. We are beginning to look at A/C options. My initial though would be a dual mini-split - one in the Main area and one in the bedroom at the back. Then I looked at the power requirements for dual mini-splits and found they all are 220V+/-. That creates problems when looking at off-grid and typical RV hookups.

What solutions have you found for this? What is the best way to cool the front of the bus while having a comfortable sleeping area?

[ewo1]

Originally Posted by melwade

We have a 40 (3 foot RE bus with a 21" roof raise. We are beginning to look at A/C options. My initial though would be a dual mini-split - one in the Main area and one in the bedroom at the back. Then I looked at the power requirements for dual mini-splits and found they all are 220V+/-. That creates problems when looking at off-grid and typical RV hookups.

What solutions have you found for this? What is the best way to cool the front of the bus while having a comfortable sleeping area?

Great question and the timing couldn't be more perfect...for me...

I too got a 40 RE Amtran and just started putting in some foam board insulation.
Thinking the same as the question you ask, I plan on double insulting the rear bedroom area.

Right now I am using some 3/4 poliso boards with an R-5 rating.
I plan on doubling up on that, two 3/4 boards for a total of 1.5 inches, to try to get as close to an R-10 rating as I can and use a roof top a/c unit just for the bedroom area.

For the rest of the bus I'm going with a mini split.

I believe on the Mini splits, 110 volts unit max out at 12k, Above 12k yes they are all 220V.

Can't wait to see the responses though on your initial questions.

[musigenesis]

Originally Posted by ewo1

I plan on double insulting the rear bedroom area.

Hey bedroom - you're ugly and stupid!

[musigenesis]

Originally Posted by ewo1

Right now I am using some 3/4 poliso boards with an R-5 rating.
I plan on doubling up on that, two 3/4 boards for a total of 1.5 inches, to try to get as close to an R-10 rating as I can and use a roof top a/c unit just for the bedroom area.

Polyiso is the right stuff if your primary concern is dealing with heat instead of cold (which I've heard is indeed the situation in Florida). Polyiso has a higher R-value than XPS when it's 75°F or hotter, but it drops well below XPS in cold weather.

[cadillackid]

for minisplits if you can swing the mounting space i would run 2 12k 110 Volt units.. the dual units end up with a lot taller outdoor unit.. by sometimes as much as 8 inches or so. the single 12k units seem to have a higher efficiency rating too..

[ABBus]

We run two Dometic Brisk ii HE air conditioner. Just the right size. Noisy, though.

[ewo1]

Originally Posted by musigenesis

Polyiso is the right stuff if your primary concern is dealing with heat instead of cold (which I've heard is indeed the situation in Florida). Polyiso has a higher R-value than XPS when it's 75°F or hotter, but it drops well below XPS in cold weather.

Good point! Maybe then I should do 1/2 iso and 1/2 XP’s in the bedroom area...??

Growing up not to far away from you, union county N.j., I still have vivid memories of the freezing cold... left jersey in ‘82 to go spend the next several winters on the northern coast of Honduras.
I remember all those freezing years, wishing I was in a tropical paradise. Well come December, January and February, Florida is now my tropical paradise!

I have no desire to deal with the freezing cold ever again!
Sitting in front of a fireplace sure is nice and cozy but then again taking it all off and jumping in the pool is much more fun!

[ewo1]

Originally Posted by musigenesis

Hey bedroom - you're ugly and stupid!

LOL..I finally caught on to the yoke.!!!!

I spelled insulting instead of insulating... LMAO....

Good one!

[melwade]

Thanks, everyone for the responses. I like the idea of the dual mini-spits. The rooftop units are intriguing - I'm just not sure about the noisier unit and the additional height.

@ewo1 - That's pretty much the same bus as ours but we have a 2003.

[TaliaDPerkins]

https://www.skoolie.net/forums/f51/230vac-bosch-mini-split-on-240vac-36231.html


My hope is that with the solar shading much of the roof and awning for the sunny side, and the original windows out and the approx 40~50 sq ft of double glazed I sub in, that 12k of cooling with dehumidification will make it OK in full sun. Spray foam insulation and sealed up tight with a "Broan HRV80S Broan HRV80S 77 CFM Heat Recovery Ventilator with Side Ports" from Amazon for air exchange. Heating in winter will be by woodstove, so no lack of power there.


It will be a live aboard usually parked in the woods in shade. 36' Thomas.

[melwade]

I've started posting build pictures here:
https://www.skoolie.net/forums/f11/f...-re-36326.html

[TaliaDPerkins]

Thank you.

[thjakits]

hi all,

I wonder about the outdoor units - I just installed a 9k unit at home and looking inside the outdoor unit - there is not much about it!
If you don't care about the warranty - you easily could fit a 2 or 3 of the innards in the engine bay....
Or talk with your favorite A/C supplier about building a unit or 2 to your specs.
All the better brands have spare parts for everything - assembling a unit from scratch is easy. Yo might even be able to integrate the indoor unit in your ceiling.... (I suppose the individual parts would carry a warranty....


thjakits

[Bon Voyage]

I went with 2 rooftop Rv style air cond for mine. 13 500 btu each and they do plenty good on the hot days. If I only have 15 amp plug I can still run 1 no problem. They just seem simpler to me than the mini split units. Drawbacks are you have extra weight and height on the roof.

I’m doing something a little different in mine that I’ve yet to see on a conversion - it’s making it ducted roof top air conditioning. I’ve owned a few regular RV’s and the ducted is always way quieter. Anyway that’s what I’m working in so hopefully I can get it finished before too long.

[cadillackid]

Originally Posted by thjakits

hi all,

I wonder about the outdoor units - I just installed a 9k unit at home and looking inside the outdoor unit - there is not much about it!
If you don't care about the warranty - you easily could fit a 2 or 3 of the innards in the engine bay....
Or talk with your favorite A/C supplier about building a unit or 2 to your specs.
All the better brands have spare parts for everything - assembling a unit from scratch is easy. Yo might even be able to integrate the indoor unit in your ceiling.... (I suppose the individual parts would carry a warranty....


thjakits

you can modify mini splits. when I installed 3 in my house in 2009 ducted inverter units werent available so I tore apart the indoor units and built my own boxes to house the coils and run off my central blower and use my nice looking floor vents instead of the fugly wall units.. they work great.. the Copper tubing is VERY THIN so be very careful if you are brazing you can burn the pipes really quickly.. I went to using staybright 8 on minisplit pipes as I can keep the torch flame a bit cooler and get leak-free connections.

[Mako]

I'm definitely thinking about going with the 2 mini splits as well. The way I figure it, worse case scenario is I can run at least 1 of them with solar no problem. I will just have the back bedroom closed off and use the front mini during the day and switch to the back bedroom mini at night when we're sleeping. And, if we are hooked up to shore power, it won't matter because I will be hooked up and can use both if I want.

[kazetsukai]

Split phase inverters can run 240V appliances, including mini splits.... we have/do run split AC/heat off the inverter. Our new inverter will even produce 240V split phase from 120V input if ordered in the right configuration.



We have one 9000BTU up front, and I want to put one more in the back when things settle down for us.

[MacC]

Great info. I also have 40ft Amtran RE. I am in the process of hiring a couple Amish teenagers to pull ceiling and side panels off. That is way more screws than my arthritic hands want. WAY MORE.