AC units Coleman Style on roof

[TN Redneck]

Ok, I have dibs on 2 Coleman on the roof style AC Units for $600, and they heat too... 35,000 BTUs each. I was doing some work back in 2014 for Metro Nashville Schools, and they had these buses with AC on them. Brand New. What are the units, what powers them, and they seemed to run off the DC system of the bus. Any ideas? Would the Coleman units I want to pick up DC, or 120ACv? Seems like alot to be DC. Just wondering...

[milkmania]

Are you selling them? Plan to use them?
Not quite sure what's going on with them

[NowhereFast]

The buses you saw most likely did not have RV airconditioners in them. A Coleman unit will be powered off 120. Although someone on here says he can run his off an inverter from the buses alternator..

To run them while driving you'll need a generator, and pretty good one too.

[pepepito]

Originally Posted by NowhereFast

The buses you saw most likely did not have RV airconditioners in them. A Coleman unit will be powered off 120. Although someone on here says he can run his off an inverter from the buses alternator..

To run them while driving you'll need a generator, and pretty good one too.

I got this :

Coleman Mach - Mach 3 P.S. Power Saving RV AC | Airxcel

and yes you can run it from your inverter but is 13k BTU not 36k so I will guess they have some serious power running them or are 12v systems.

[cadillackid]

I run a portable air-conditioner (12k BTU softstart) off of a battery bank and charge the batteries with my alternator when the bus is running...

i can also run that portable unit as an aux unit on the road when my road A/C cant keep up (my bus is uninsulated and has clear windows)...

I did a post on another thread about actual watts used from the bus electrical system to run a single unit.. I dont see a way to run 2 of them off of a bus alternator / inverter.. you'll want a generator that you can run while going down the road or install road A/C (which unless you get someone;s take-off and restore it will cost you alot.. so i say put in a generator since you'll likely want one for boondocking unless you are going to plug into shore always when parked).

-Christopher

[Geo Jeff]

My alfa motor home has a house heat pump air conditioner installed underneath. They say its 40 percent more efficient than 3 roof top units in hot weather. It runs on a very low amp draw on 110 and if i plug in 50 amp it doubles its ability. I put a mister on the unit I screw on to a garden hose and when on 30 amp plug it works amazing sucking that heat off with water. plus it barely takes much water to do that. . down the road its running on the inventor. They say it works so well because its not in the sun and ducted through the bus underneath blowing it forward and then drawing it back in the system from the rear. its very even every where in the cabin. I'm doing the same thing on the schoolie. Its hard to beat these big giant evaporator and condensers. My buddy does HVAC and was saying there are a ton of options for sizing plus there are a ton of large units at the wrecking yard for trucks. this alfa has 3ft by 2ft air intake I think mounted behind a door on the side.

[Geo Jeff]

Plus with the low roofs you dont have that roof mounted unit to run your head into.

[cadillackid]

another option is you can repurpose a reefer.. they have their own engine and everything... Thermoking ones could be mounted under a bus and put the coils inside and power it vias its own diesel engine..

-Christopher

[Geo Jeff]

I had actually been talking to the guys around here about mounting the compressor on a small 2 hp Honda engine. I think its the 50cc. hook both the fan and pump to it and run the stat and controls with the house power which should be a very small load. I see more and more people getting enough panels together to run there A/C in the dessert. Maybe it can be mechanical set up with out relays on pressure and temp switches. Would just sip the fuel

[cadillackid]

im not sure if a 50cc engine would spin a compressor or not.. all depends on how much tonnage you are trying to get.. as far as the engine.. you can use a mechanically governed engine similar to a power washer or such that idles down when its not under load.. or even an electronic solenoid that would udle the engine when the compressor shuts off...

you would likely want a dual thermostat system and use a TxV.. tstat 1 could be a pressure switch but i would use an electric Freeze-out switch set about 32-33 degrees coil temperature.. and then you would want a room thermostat to shut the air off at a preset room temperature...

your TxV will unload the compressor and make the engine work less hard as the coils cool down.. but a TxV wont entirely prevent freezing.. you must run a minimum refrigerant flow through one or you will not have oil return to your compressor... so you still need the Freeze switch so you dont freeze it up under low load..

-Christopher