Under bus home ac units

captainkf · 04-02-2005, 09:13 AM

Hello All! I was looking at pictures of very high end A class coaches last night and came across a unit that had under floor ducting for heat and AC. The AC units were located in the basement and looked to be like the units people use in there houses.

I have been considering an alternative to a ceiling mount since I purchased my bus. I am 6' 2" and once I have footwear the ceiling is awfully low. So adding more things to hang below it or protrude is NOT what I am after. The concern is buying a machine that does not hang down too far. But I already have a container that hangs down 21" for my propane tank that runs the appliances. Also the generator, which will/would be housed in a compartment in the rear of the bus or the roof in a compartment.

I like the price of the residential machines. If one were to build a compartment that housed the ac unit allowing apropriate ventilation and direct the cool air up into the bus via floor vents I think it could work very well. You could even have one at the front and a seperate one at the rear for keeping sleeping area's cool in the evenings.

This way the unit(s) would be out of the sun and UV rays which over time break down plastic, not interfear with a roof deck, and be much less noisey for those on the bus and those outside of the bus.

Just a thought at this point, but I don't see any reason it would not work. -Richard

Ryan Grimm · 04-02-2005, 11:06 AM

You'd need some sort of ducting and fan to get the cool air up from the "basement". A blower fan from a car heater would do the job, 12vdc and cheap at a boneyard. A small transformer can convert 120vac to 12vdc.
Or, use a small squirrel-cage blower 120vac for the system.
Ducting the FILTERED return air directly to the intake will help efficiency.

Controlling the units may not be hard, some come with remote controls nowadays, you could use a window or mirror to direct the commands to the units. Ever use your TV remote by pointing it at a mirror, reflecting the signal to the TV?

Plenty of rubber mounts to hang the unit would help with vibration, etc.
We used 'shouldered donut'-style muffler hanger isolators when I worked in a Meineke shop, I think they'd work well as isolators.

captainkf · 04-02-2005, 09:55 PM

I thought the fan that blows the cool air if ran through 6" insulated flexible heating duct material, if not being run too far to the interior of the bus. But the fan is an interesting idea. I still have the blower unit from the middle heater unit that came with the bus.

The remote. I thought I would just exit the bus to adjust the settings. However the remote is an interesting idea. Thanks.

-Richard

busone · 04-04-2005, 11:31 PM

I am planning on doing something similar to this. I can usually find used wall AC units for almost free. One guy I talked with on another board has actually bent the evaporator up and installed it in the bus. He the built an air handler around it. I am thinking about using two 12-15k BTU units to chill a tank of water and antifreeze. I also want to get two automotive AC systems to run off the engine while I am traveling. The auto AC systems will also chill the water. I will then pump the chilled water through two air handlers. I will mount one under the dash to keep the driver and passenger cool and another that ducts the air to the rear bedroom and the kitchen area. I know this sounds complicated but I think it will be easier and much cheaper than buying expensive RV ac units and expensive inverters to run them while traveling. The other benefit I see is I will not need to run refrigerant lines as far since the water tank will be close to the AC units. That way refrigerant leaks will be less likely and the system will require much less refrigerant.

Ryan Grimm · 04-08-2005, 11:50 AM

Busone, sounds like a good idea, ducting the A/C outputs....the water chillers sound complicated, tho. And heavy!
Home Power magazine has done articles IIRC on low-tech and do-it-yourself A/C systems, including low-voltage and belt-driven units, plus supplier lists. It's been a while since I had a subscription to their fab magazine, check their web page (google it).

I've seen free A/C window units on Craig's List, and also on local Freecycle lists as well. 110 and 220 VAC units, all sizes.

For me, the local Craig's List is:
http://boston.craigslist.org/
There will be a sidebar with links to other Craigs Lists around the world and U.S.A.
Google Freecycle, find or form one in your area.

captainkf · 04-10-2005, 01:38 PM

Well, I have been thinking about this whole ac situation (or lack thereof). The new plan is to install the unit in the living quarters of the bus, right beside the furnace. Cut a whole in the side of the bus and vent the unit that way. I will build a box that the unit will be enclosed in that is insulated with pink foam insulation for sound and heat. This way I do not have to cut holes in the floor, build under bus compartments, and such. The only down sides of this system are possibly increased noise and loss of interior floor space. The noise should not be much of an issue though. Traditional RV roof top units are not the quietest units either.

I looked through the local used paper and found a couple units for around $60.00. So the price is right.

I'll keep you posted.

-Richard

lapeer20m · 04-10-2005, 11:15 PM

remember there are not only holes on the back side of the a/c unit, but there are also holes cut in the sides, and they need airflow too!

i learned this the hard way in a black bus parked with no shade in sunny california during the summer.

busone · 04-11-2005, 12:14 AM

Also be careful of how the units are designed to dispose of condensation. You don't want to be on a hill and have it start leaking. Some of the larger units have a drain plug on the back bottom.

captainkf · 04-11-2005, 12:54 PM

I was not sure about the rest of the unit requiring air flow, but I did have a hunch. What if I were to leave 2-3" around the unit that vents to the outside? Mabye run a 4 inch mesh around the unit on the outside to keep unwelcome things on the outside of the bus, with a drip pan on the underside of the unit that drained to the exterior of the bus. Then the insulated box around it on the inside of the bus.

For those of you who live in hot year round climates, does this sound like sufficient air flow around a unit? It has been 9 years since I have needed one in my home and I just don't remember.

I have seen them installed in the rear windows in the back of buses but that won't work for us because I plan to keep a small area for storage using the door.

I just don't want to spend $500 for a USED unit. I don't know how much we will need it, but I do remember Ontario and Quebec being very hot and humid. Does anyone have any other simple solutions?

Thanks - Richard

busone · 04-11-2005, 10:01 PM

I have thought about installing the unit inside the bus in a cabinet like you are thinking. I would run a 5" duct for supply air and a 5" duct for the hot air to exhaust. You could test it out in a cardboard box before you build it in the bus to be sure it has enough air. You can go even smaller on the air supply just install a powerful fan to force air in the box.

bdavis441 · 08-01-2005, 08:14 PM

I have finished my installation of the a/c in a cabinet inside the bus. This cabinet is sealed and insulated where the unit is, upper half is storage. There is an exhaust duct to the outside that also will drain condensation. The space around the unit serves as an intake plenum that draws from the outside as well. There is a louver on the outside for intake and exhaust. I got a 12000btu unit on clearance at wal-mart for $179. Seems to work quite well so far, but I haven't taken a trip with it yet. I have posted pics of this setup in the gallery (Big Blue) Check it out, any feedback good or bad will be appreciated.

Brad

Griff · 08-01-2005, 09:07 PM

Very nicely done! Looks like a clean, well thought out installation. I hope it cools the way you planned!

I'm curious about the louvred panel. The louvered duct on the original vented heater in my bus had a much smaller louvre pattern that allowed a lot of wind & water to blow in (until I blocked it off & went unvented), how much wind/water proofing will your louvre provide? I'm not sure if I'm asking this clearly, but is there a difference in the angle of louvres, or how far one rises up behind the other that helps prevent this type of weather intrusion?

busone · 08-01-2005, 11:53 PM

Nice job on the install. Sure beats the high price of the roof warts, it also looks much better.

bdavis441 · 08-02-2005, 05:33 AM

Thanks for the input guys, it's nice to get a little positive reinforcement once in a while. The louvers are of a design we use for architectural sheet metal installations, look at big louvers on large commercial buildings and you will notice the similarities. I have been in mechanical rooms with entire wall made of these louvres while it has poured rain and nothing comes in. That's why I used this design. Each louvre extends up behind the other by the size of the lip, 1/2 inch in this case. To get a direct path through, it would take an upward angle of about 15 degrees. As far as rain splash, they are situated as such that a rather angular rain will only hit about the bottom half of each blade, to splash all the way in it will have to travel all the way up and over the 1/2 inch vertical lip at the top of each blade. So, as long as you don't shoot the garden hose in them, they are weatherproof. l

bdavis441 · 08-02-2005, 05:36 AM

I forgot to mention wind intrusion. The cabinet is sealed from the inside of the bus, so wind can will only blow into the a/c intake (no problem) or exhaust if it's not running (no problem either)

Griff · 08-02-2005, 12:10 PM

COOL! (Literally & figuratively)

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