Bus A/C Options

[Joe Camper]

I agree with Hi yo silver.

I did spend a few thousand getting ours up in 06 when we bought the bus but haven't spent a penny on it since.

Where does the ongoing annual expense come from I haven't experienced that.

1 thing I do not like is the inability to run just the dash loop if and when I choose. Hooked a cruisair up to inverter to remedy that.

For info sake you do not need a big battery bank to run ac off inverter. I use a 2500w inverter 4 automotive sized deepcycle flooded wet cell batts and the 50dn alt. Works flawlessly all the time.

Many different ways to get there with a/c important thing for me is I have slightly more than I need. I know 2 roof air will reasonably cool a 40 ftr even on a hot day but what if 1 goes down? I think we will be keeping the 3rd one we have. If you are using calculations for a residential situation I would about double the figures for capacities.

Running the A/c off inverter or running the gen for a/c uses fuel too. No free rides

[Hi yo silver]

Just as info, the work on my OTR a/c cost me around $450 about two yrs. ago. If it had been several times that amount, then I certainly would have reconsidered. One other point, I didn't rely on my own expertise, I took it to Thermo King. They knew how to evaluate the system, knew what would work in it, and I trust their advice. So far, so good.
Dennis

[luvrbus]

2 roof tops will cool a 40ft bus when parked but not will driving and 2 roof tops parked are a little iffy here in AZ in July I have saw H-45's and they are supposed to be easier to cool than a xll here with large basement units the people spraying the bus with water to help with cooling.
They don't install 5 or 6 units for nothing and no way can you replace 10 or 12 tons of cooling from the factory with roof tops or basement air won't happen in the real world lol that is my take on it.
On the OTR air I have a friend that owns Arrow and he says the OTR air is his most expensive maintenance item on his buses but he runs his buses every day some where on this board I posted the numbers he gave me and it is not cheap 


good luck

[lostagain]

OTR air is great when it works right.

However, it can be expensive to maintain: when I looked after the hockey team's bus, it had to be recharged once a year at a cost of =-$1000. They were small leaks than nobody could ever find.

When I drove  that vintage of bus in the '70s, we always had to turn the A/C off to go up most hills so as to maintain decent speed. OTR A/C uses a lot of HP, and will knock you down one gear in a 4 speed going up a hill.

JC

[TomC]

With my truck conversion-I'm teeing into the truck A/C unit to run a slave unit (like what is run in a sleeper) to keep the front of the living area cool/warm.  And since my roof line is too high (13' then 13'6" at the bedroom), I'm directed at basement air.
I just talked to Nick yesterday.  My idea is to use Duotherm Penguin roof top airs mounted in the basement section.  The Penguin is the only roof top air that has a squirrel cage blower for the condenser that can be ducted out of the basement.  Granted it will take a bit of engineering, but once in, I can also replace the units if one fails.  They run about $900.00 each-so $1,800.00 for two.  In the cab, I'm going to run a 7,000btu Duotherm truck basement air.
The other choice is to run CruiseAirs.  These are freon split A/C's.  So with the front, I'd run the full 14,000btu to the living area.  The mid A/C would be freon split with 7,000btu to the front and 7,000btu to the bedroom-like a night time A/C.  But-Cruiseairs are exactly twice the cost of the roof tops.
There are also the fore mentioned mini splits intended for home use, but very difficult to duct the hot air out of the basement.
Also is DC air that is about a 6,000btu 12v or 24v dc powered A/C aimed mostly at trucks.  This might be a good one for night A/C so not to run the generator.
You could even modify through the wall A/C's to work.
Lots of choices-just have to find one that will work for you at the cost you can bear.  Good Luck, TomC

[John316]

Clifford,

Thanks for weighing in. I wondered if we did something really wrong on our bus, since it takes at least three airs to cool when driving (or just two up front). Four is nice, and keeps everything nice and cool when we are down south, or in the desert. We have spray foam, and everything, but two roof airs just won't cut it.

But, it looks like we are simply normal.

God bless,

John

[Len Silva]

As far as I know, the basement air from Duotherm are basically repackaged roof airs.  The main difference being that they use separate motors for the condenser fan and air blower.  I had basement air in the bus and now have roof airs on the Vogue, and I would give up the bay space in a heartbeat for basement air.

Much, much quieter and better circulation (with proper design).

[artvonne]

   I really hadnt thought I would run into so much opposition on the subject. I did not mean to offend anyone about roof airs, and I appologise immensely for anything I said, or how I said it. Please accept my appology.

 

   
   

 

 

 

[robertglines1]

I stepped out early in this discussion.I said I was using mini split system. I did not mention that I do have a drivers air that is driven off a small compressor on the engine:I understand it is a 2 ton unit. I have it as a back up or primary how ever it may end up. My coach is insulated to maximum capacity of space available with a minimum of glass area. Bob

[luvrbus]

The drivers ac is a lot larger than 2 tons most were 28,000 to 33,000 btu more than both of your split/units combined

good luck

[robertglines1]

Thanks for info: guess I got a good cushion. nice to have extra available if you need it. I will give truthful response after the summer months have come and gone. Guess I'm one of the test markets. Was really impressed with others results and Duwayne (a friend) results in his Mci 8.

[JohnEd]

  I really hadnt thought I would run into so much opposition on the subject. I did not mean to offend anyone about roof airs, and I appologise immensely for anything I said, or how I said it. Please accept my appology.


You already said your "OOOPS!" thingy.  Only a very few are really sensitive about almost anything.  My observation, anyway.  Of course with 5 peepbels ignoring me, I could be wrong but 5 out of three thousand is nothing short of a "murakul" as far as I am concerned. Though it demonstrates your concern for us and that is truly a plus.  "Now just stop being so cussed abrasive".  YAR YAR YUK...

John
 

   
   

 

 

 

[JohnEd]

I have heard many say that the roof airs don't cut it when going OTR.  More so they say that a couple are good when stopped but three aren't enuf underway.

It matters vary little how much AC capacity you might have on tap......you don't need many "leaks" to nullify their affect.  There isn't a state in the union that you can cool with any AC unit. (sarcasm).  Quit trying.  (more sarcasm)   Fix the air infiltration leaks.

There are many 40 footers that stay cool just fine almost anywhere.  If you have the same thickness of spray foam throughout it doesn't matter what model or make you might have.  Each should require the same Btu's to operate satisfactorily.  I am not gullible enuf to think that it works out that way and you don't have to dive very deep into the posts on the search to come to the same conclusion.  Why?,  i dunno!

In homes we put foam pads in front of out duplex outlets under the face plate.  Conduit will act like a mini duct to bring in air.  Wire penetrations are virtually open holes.  Mating points of structural panels and braces are often gaping even though they are mechanically strong.  Fiber glass is worthless as insulation of air is being pushed through it.  Our furnace filters don't provide much insulation and they are FG, right? (sarcasm,  again).

The front of a bus can be expected to be a high pressure area and any HOLES will admit air like gang busters.  There must be many other places that have high pressure outside air.  Here is the rub and seeming contradiction.....most buses have a "LOW pressure" inside while underway.  Even without the high pressure areas the thing "sucks" as it goes down the road and that "suck" is in "series" with the "push" from outside so you get a push/pull affect and even MORE air.  Hot or cold...doesn't matter cause they are ambidextrous.  Or was it by-lingual

As you drive down the road at your normal cruise, have somebody crawl all over the interior walls and floors and cabinet interiors and any merge of a wall and floor or roof or duplex out let or pipe or duct..... all over.  Not so much for the fun of seeing them do that but arm them with a no contact heat sensor from HF,  sold for $29, and note temps.  Now it can't be one of those days when the outside is the same temp as the inside....the heating or cooling system must be trying to alter things.  These air permeations kill the temp change efforts while underway but they are also very bad when you are parked and wind exacerbates everything stopped or OTR.

Glass is a really bad culprit.  Double pane AND with that solar load rejection feature are really critical.  You can defeat the bad behaviors but it ain't cheap.  No matter the quality of the view, if you are freezing or cooking.....it ain't a pretty pic-shure.  While glass is expensive, it gets intolerable as a "Do Over" so get it right the first time and don't scrimp on the spray foam...an R here and a R there adds up and eventually you are talking a Btu or two and discomfort.

Want to see how much "suck" is going on in you bus?  Open one of those front drivers windows while at speed and note the air blasting "out" the hole.  My drapes stand out straight out the window.

I hope someone will do a survey of their bus and let us in on the conditions and maybe even get a survey for different models/makes.  I can tell you that my Winne, 30 footer, is crappy and CANNOT be corrected with any reasonable amt of work.  Sitting still, though, in 90 plus temps in the sun I can keep the interior down to 70 running only one AC unit and it cycles maybe 50%.  Roof is R50 in the center and tapers to R20...or thereabouts.  All windows sealed with film and dash area insulated to maybe R14.  I didn't do all that cause it was needed but primarily cause I could.  It worked!  OTR?  Only the drivers area is habitable.

Wellllllll!  That was fun.

Be well and happy all,

John

[TomC]

I have three 13,500btu Coleman roof tops with the front close enough to blow on me when driving and with a dash fan.  We normally run just two of the roof tops-108 degrees is the hottest I've been in. I have tried all three running, but then my wife has to wear a sweater.  It all depends on your insulation.  Good Luck, TomC

[Geoff]

I have three 15,000 BTU AC's on the roof and I never have to run more than the middle and front unit to keep cool.  The killer is driving into the sun--I don't care if you have 100K btu's, the sun through the windshield will cook you.  Especially on a modern bus (like the RTS) with the large windshields.