Bus A/C system conversion?

[Jerry32]

Has anyone aver tried to convert the bus system to a stationary system run fron ac power? seems you could put about a 3 ton capacity compressor in somewhere and hookup to the coach system and have a basement system. You wouldn't need as much cooling as the originl as you would not be cooling 50 soles , just the space in the bus. The condenser blower would not have to be as large and could use 2 or 3 blowers or fans with thermo switches to kick in with tem rise. Maybe you could use some valves like reversing valves in a heat pump to switch to the road system. The engine driven compressor would not need to be as large either and could use a smaller one cutting down on the amount of HP used to run it.  I suppose this is just a wierd idea but I thought it seemed feasable   Jerry

[kyle4501]

While not impossible, it is usually problematic to run multiple compressors in the same system. It can be difficult to keep the right amount of oil in the compressor. If you over fill with oil, you can run into other problems like it 'ponding' in the condenser & accumulator.

So if you do decide to have multiple compressors, make sure you understand the little nuances to avoid problems.

Might be easier to add a second system & have dual condensers & evaporators in the same location. Then you have a little redundancy if one system takes an early retirement.

[Nick Badame Refrig/ACC]

Hi Jerry,

Have you concidered driving the 5g compressor with a electric motor?

This can be done with a reduction gear box and still maintain a comfortable 50deg. evap.

The question is, how are you going to drive the blower motors? 115v motors will also work.

The condencer cfm's will be the most critical.   Well, start adding up all the amp draws of theese motors

and this will determine the efficency.

Good Luck
Nick-

[DavidInWilmNC]

Jerry,

Why not take a look at www.danhard.com.  There are all kinds of parts and complete units that could make for a decent bus A/C.  Alternately, you could duct the orig. bus HVAC and a basement heat pump (or A/C) through the same ducts and have OTR and campsite units.  This would probably be a lot easier, more reliable, and cheaper.  I'm kind of doing this.  I'm changing the original OTR heat and air to blow through ducts and registers instead of up along the side walls below the windows.  It'll be relatively easy to add a basement unit if/when I ever feel the need to or get tired of roof units.

David

[Jerry32]

I always wonder about the efficiendy of the roof aris as their condensors are up in the heat on the roof just at the time when you need max heat transfer. as for the blowers why not DC as running an cinverter for power . then no change. I thought about an electric powered compressor using the bus compressor but thought it would take a monterous moter but yes ir runslower like as when the engine was idle it could be done. I kept my ducts in the front as I didn'see any problem with them. The returns in the rear could use floor registers and the same with the fron return. Jerry

[Hartley]

It also depends on how much of that 20 year old "Human Chaff" that you want to breath, It gets embedded into everything
in old buses. Like a rolling Bio-Hazard.

A lot of buses look clean, But when you get down into the A/C systems you learn the difference between clean and awful.

You would be better off taking a package unit apart and placing the components where you need them. Or maybe a mini-split system which are now available. Some even in 120 volt units ( special order chinese ).

[DavidInWilmNC]

It also depends on how much of that 20 year old "Human Chaff" that you want to breath, It gets embedded into everything
in old buses. Like a rolling Bio-Hazard.

A lot of buses look clean, But when you get down into the A/C systems you learn the difference between clean and awful.

How true!  I'm getting ready to rip up the front section of floor to run some ducts and clean out all the nasties.  I'll have to find some pics I took of the return air area and post 'em.

David

[TomC]

There's a real good reason why the vast majority of RV's run roof top A/C's-because they are cheap, reliable, out of the way, take little power to run, and extremely easy to replace.
What you're talking about doing is going to take a monster amount of experimenting, custom equipment to try to run that big compressor-or try running an additional compressor, running a big converter to run the 24v blowers, etc.  I see it as nothing but a headache to set up, then even more money to try to keep it running.
I have a 40ft x 102" wide transit with huge windows, 2.25" blown in foam, and run three 13,500btu Coleman roof top A/C's with the conventional hang down diffusers.  Two of the roof tops will keep me cool while driving up to 100 degrees, then I can just kick on the third.  The entire cost of installing the three A/C's including the electrical lines was less than $2,000.00.  And in the 12 years they have been installed in the bus, they have required NO maintenance (up and beyond cleaning the filters once a year, and one exterior shroud).  You can't get much better, or cheaper than that.
If you don't like the look of the roof tops (which I don't like the looks either), then put in engineered basement units.  Look at the Dometic site at the Tundra based either all in one or split units.  The all in one requires you cut  two about 3" x 6" holes in the floor for the in and out of cooling air.  The splits (my choice) would only require two small holes for the freon lines for the exterior electric fan condenser.  They are available in either 11,000 or 14,000btu and are designed for use in over the road big rigs, so you know they will take a lot of punishing treatment.  The interior unit has the compressor and evaporator in it.
As with any of the systems on the bus (especially the A/C-that would make any trip during hot season miserable if it quit), I highly recommend you keep with systems that have been tried and trued for many years, instead of trying to reinvent the wheel.  Believe me-you'll be a whole lot happier, and with a lot less trips to the bank.  Good Luck, TomC

[Jerry32]

My experience has only been with a 32 foot motor home diesel pusher with two rooftop airs and a working dash air. Going down the road at 100 plus degrees with the generator running and both roof top s on and the dash full on I could not get it cool inside the coach. I just thought that by reducing the size of those blowers and the smaller compressor would make sense to use the xisting ducts for curculation. I use heat pumps in my house and my shop and they are low maintainence and reliable. even when I leave for 4 months in the winter for the last many years the heat pumps continue to operate without fail. I see others talk about using basement air conditioning theis would only be and adaptation to that. Jerry