24volt dc roof top ac

[sledhead]

Hi guys  has any one used a roof top  24 volt dc air conditioner like the dc airco  dc 9001. I saw one on a local semi truck ,asked the driver how well they worked he said he can use it for 6 hrs over night with battery only (4  12v ) and it works great.I wood like to use it as a on the road ac off the bus 24volt battery well driving,I have a 9000 btu split heat pump ac that I use now with the inverter but on hot days above 95 f it can't keep up after 2 hrs on the road.                 thanks    dave

[bevans6]

I looked them up on-line and they look kind of cool.  The 9,000 btu one you quoted is probably a little on the small side to do much with your bus on it's own, but they also have a 13000 btu model.  Power consumption is quite good - the 13,000 btu model uses 1200 watts at 100% duty cycle, no starting surge they say, so that's only 50 amps at 24 volts.  I bet they cost pretty good, though.

Brian

[gus]

Only 50 amps!!

[luvrbus]

James has 2 Cruise N Comfort DC airs in his bus there are 3 compressors in each unit don't ask me why, you can run all 3 or 1 when running 1 at night they draw 16 to 18 amps pretty pricey at 2300 bucks each for his units and he loves his

good luck

[Lin]

Gus, I assume he is talking about 50 amps at 24v.

[Tony LEE]

Big problem with cooling a bus while moving is air infiltration through all the various holes, cracks and gaps, especially in the front of the vehicle. Add to that the huge radiant heat coming in through the windscreen (and often shining directly on you) and you need a lot of BTU to make much difference
It doesn't take too many cubic feet per minute of 100F air to completely counteract the relatively puny effots of one of those 24V units (which are really only designed for the relatively small sleeping cabin of a stationary truck

[sledhead]

ok  is there a way of insulating the front of the bus as yes in the winter a lot of cold is coming in well driving ,no breeze to speak of but must be the same in hot of summer.my ac I use now will do most of the cooling now .but would like more cold .any ideas ?          thanks     dave

[luvrbus]

The old fashion way is best the automotive set setup with engine driven compressor 30 to 40,000 btu will cool you,check into the units like Pro/Air with both AC and DC operations that is the type emergency vehicles use and can be bought at wrecking yards

[TomC]

I looked into the DC roof tops.  They're about twice the money for a normal 120vac roof top A/C.  Plus-if they break down-where do you have them repaired?  With a Duo-therm or Coleman-just go to a Camping World or such and buy a new one.  Replaced in about 2 hours!  Good Luck, TomC

[belfert]

If one spends most of their time parked and not driving down the road a 24 volt DC air conditioner will likely use extra power due to the 110 volt to 24 volt conversion.

[sledhead]

Mabe my son is right and I should install a curtin behind the driver , pas.seat like the old sticks,staples rv we started with . The split unit ac we have now is above the winsheld and would probobley work fine          thanks   dave

[bevans6]

My thinking is this - if you go with a 24 vdc unit and want to use it for long period of time with the engine off - you need a big charger/power supply to keep up with it's power demand.  If you go with a 120VAC unit, you can use it forever when parked, but you need a big inverter to run it on the road.  The costs are a wash - the cost of the DC unit probably matches the cost of the normal roof-top and an inverter big enough to run it.  You need a big charger anyway, so having one is a wash.  You need an inverter anyway, so having one of those is a wash.  Tom's idea on the 2 hour replacement when the roof-top inevitably dies is a good one - and even works, as long as your inverter lives forever...  Conclusion - ain't no easy, cheap way to keep cool in a bus... choose your poison, they all suck...

I would personally go with an inverter and a roof-top.  Maybe 80% - 90% of my use of the air conditioner is plugged into an external 120 vac supply, so go with the most efficient normal use mode.  Truckers use pattern is very different - run it from a battery bank for 6 - 8 hours at a time, never use it while plugged into a pole, never use it on the road (dash air works great in a truck, I would think).

Brian

[TomC]

When I bought my inverter, I wanted to buy two and stack them to have 5,000 watts and run one or two roof tops off the batteries.  The gal that sold me the inverter asked if I had a Diesel generator, I said yes-she said just run it off the generator and then sold me just one inverter.  Battery powered is a really inefficient way of powering much more then lights and occasional microwave, TV and such use.  If you compute the efficiency percentage after all the power losses, you probably would only be in the 70-80% efficiency range-compared to around 95% for a direct driven A/C off the generator.  Good Luck, TomC

[Pixelhead]

James has 2 Cruise N Comfort DC airs in his bus there are 3 compressors in each unit don't ask me why, you can run all 3 or 1 when running 1 at night they draw 16 to 18 amps pretty pricey at 2300 bucks each for his units and he loves his

good luck

The Cruise N Comfort units require a fresh water input from under a boat's waterline (for cooling of the unit, I'm assuming). How did James set his up? Did he make a loop with his freshwater and if so, what do you do when you're low on water. You'd also have to be running your water pump constantly to get the water to circulate.

I love the idea of three compressors so that it can cycle some of them off when not needed, but I don't see how their units are really designed with RVs in mind.

Would really like to know more about what James did with his... is he on this board, or can you PM me with his email address. I'm converting a 1963 Flxible Starliner and need to choose my air conditioning setup very soon.