How many rooftop a/c's?

[MikeH]

Hello everyone,

This is my first official post to the board here. I appreciate everything that is shared and hope someday I will have something to contribute besides questions. However, at this point I have a lot of them, so I am going to start posting some.

I am in the thinking/planning process. We don't currently have a bus, just dreams of having a bus. It will be for pretty-much full-time use by our family of 6 as we travel around the country singing Gospel bluegrass music. Starting in the back, there will be a bedroom for my wife and me, then a bathroom, then bunks for the kids, then a living area, and last but not least, the driver's area. We will probably end up with a 40' bus, most likely a 96", but possibly 102. We don't know where or when we will be traveling at any given time, hopefully not in AZ in Aug or in MN in Jan, but you never know, anything's possible, and I'd rather plan for the worst (AZ in Aug), than not and regret it. Given that limited amount of information, how many rooftop air units should I plan on putting in? How many BTU's will it take to keep the bus cool, and will I need to have zones? I don't really know how zones work, does one unit cover a single zone (i.e. bedroom and bath), or do they all fire at once and direct the output to the zone that needs it? Does each zone have it's own thermo?

Thanks in advance for your help.

Mike

[eddiepotts]

Mike, first off welcome. I was in your spot a few months ago. You are asking like you want to build a bus? I would suggest looking at an entertainer for what you need. That's what I did only for the reason I needed to sleep about 10 people at our camping event twice a year. I do have the back as a bedroom and the middle bathroom and 9 bunks. You could take some out in your case for more closet space. Then up front I have all the comforts of a living room and galley. I have 3 roof airs one for front, middle and back. The middle closes off to where it is total darkness for late sleeping and keeps everything cold. If you shop it out right you can really find the deals out there. A leasing company has to move out the old to keep up with the stars. They have made their money with them and it is not for the retired couple touring the country. They make a great base to start with and the deals are out there.

[TomC]

I have a AMGeneral transit with very large lightly tinted windows.  I also have 2.25" sprayed insulation (this is the key).  I have 3-13,500btu Colemans-one up front to blow on me, one in the middle, and one over the rear bed.  In 108 degree weather while driving (the hottest we've been in) just two running (front and back) will keep the bus in the mid 70's.  Running all three, and my wife has to put on a sweater.  Once again-good insulation, tight fitting tinted windows and no other leaks are the key to a cool bus.  Good Luck, TomC

[wal1809]

Mine has 3.  I have nit needed all three but I have not been in 109 degree heat with it yet.

[bevans6]

I think the number of adult (or full sized) people in the bus has a lot to do with it as well.  6 is a lot for a converted bus.  I would start with three and go up from there, if you are talking rooftops.  Look at a big generator installed to run all the time as well.  Or just look for a used entertainer bus.

Brian

[MikeH]

Thanks for the replies so far. I don't think an entertainer coach is really an option. We would end up taking a lot of the conversion out to make it work for us. Entertainers rarely have a rear bedroom, a shower or any kind of workable kitchen, all of which would be important for us. I think a better option is to start with a bare shell and build it up the way it will work best for us.

Assuming I need 3 rooftops, how big a generator will I need?

Thanks,
Mike

[belfert]

Three roof airs should be doable (depending on other loads) with an 8KW generator as long as all three don't start at the same time.  This assume propane water heater.

If you want to not do any power management and run anything you want at any time you'll need to go to 10KW or even 12.5 KW.  If you buy the larger generator for the worst case scenario you'll need to remember that it will burn more fuel all the time.

[TomC]

With my three Coleman 13,500's, I have a 10kw Powertech.  With my truck conversion, I'm using a 12kw-a new model that Dick Wright made up for me with a 3 cylinder Kubota D1305 engine and a newage alternator end.  The whole generator is 35.5" long!  Good Luck, TomC

[wal1809]

I use a 15 KW powered by a Kabota fuled by the main tank.  My wife turns everything on all the time.  Never had a power problem.

[BG6]

Hello everyone,We don't know where or when we will be traveling at any given time, hopefully not in AZ in Aug or in MN in Jan, but you never know, anything's possible, and I'd rather plan for the worst (AZ in Aug), than not and regret it.

I would plan for the worst that you actually expect, rather than the worst that might happen.  If it gets worse than that, it would only be for a short time and it might be more cost-effective to just go into a motel to cover those.

Most folks seem to go with either 2 or 3 roof aircons. 

However, you might be better off using the "portable" aircons that you see at the big stores this time of year.  There are several options for where to put the heat dump vents (out the side, through the roof, through an open window).  They need no installation (thus no roof leak issues), you can store them during the rest of the year, they are cheaper than rooftop units and you can replace them pretty much anywhere if one goes bad.

[belfert]

Remember, Sean is trying to trade a 15KW generator for an 8KW because it is just too big and sucks too much fuel.  To be fair, I suspect Sean and Louise are pretty adept at power management plus they have a load sharing inverter that can help.

[John316]

Welcome aboard, Mike.

The issue about roof airs depends on everything. We have five 15K roof air conditioners. They are powered from our 20KW generator.

However, what color your bus is, how much insulation, etc. You can probably do great with two or three. WE have just done an overkill on most of our things (because when we travel, we are on a schedule, and can't be down for any length of time).

FWIW

God bless,

John

I am also sending you a personal message.

[MikeH]

Thanks for the replies so far. Please keep 'em coming. So far the consensus is that three is a good number of rooftop AC units, but maybe we start with 2 and add another later if needed.

Belfert: We won't be going with anything propane. Not a risk we are willing to consider. We will probably go with an Aqua-Hot for hot water and heat (subject of future posting).

BG6: I admit to an interest in the portable units from the standpoint of no possibility of a leaky roof. Are these like window a/c units you would put in a bedroom window? Any more info on them I'd appreciate it.

John316: Insulation will probably be a big thing. I haven't gotten to planning that yet. I pm'ed you back. Thanks for the note.

Mike

[Just Dallas]

Removed

[Bill B /bus]

Mike

If you are converting the bus then consider the following:
Insulation  - spray foam is best

Windows -  dual pane. Yes expensive but in your case needed due to noise and insulation value.

Floor - insulation to cover the drive axle area. Accept the hit on clearance and add at least 1/2", I'd prefer 1", to the floor.

Webasto heating system - Although Webasto is getting expensive it is the best. Consider also Hydro Hot and Proheat. You can build your own system with MSR heaters and baseboard.  AquaHot is just a Webasto in a fancy case.

AC units -  Get three 15K BTU units and send the air to a central duct. Ducting will reduce the noise a lot. Your people load is going to drive the heat loading up. That's why three 15 K AC units. The control system for maintaining temperature is beyond my knowledge base but it is doable. High end conversions did it before computers.

Bus - A 102" will serve you much better than a 96"  The 6" is in the aisle as the furniture and appliances are standard depth.

Good luck
Bill