HVAC Questions

[mtrobertson]

I am getting close to installing the HVAC. I realize most of you recommend going with a mini split, but I already have a window units sitting around unused, so it's hard to justify spending the money.

My plan:
Heat - Diesel heater (open to recommendations on which one) ducted to move the heat throughout the bus.
AC - Window unit in back and another in front, I have a third if I really need it.

My question is.......... Is there a reliable way to put the window units under the bus by the diesel heater, and utilize the ducts? I have ample space under the bus, so no concern there.

I am happy to take some jesting for doing things different than you and possibly even stupidly. Most of the digs I have gotten have been humorous to me, but many are also pointless. It is much easier to take the jesting if the reply also includes something constructive.

Thanks

 

[nikitis]

Window units could work. I like to do things differently as well. If you have mounting space under the bus and it’s vented to outside and if you duct into the bus it could work.

How well depends on size and BTU of unit and how well your ducting is routed. Cold air falls so if ducting is only to floor your feet will be cold but not upper bodies. You could combine a couple of max air fans to release the hot air and draw up the cold air with pressure.

On a 30+ foot bus a single window unit likely won’t be enough for a whole bus. Smaller than that, maybe.

Just some thoughts.

 

[desrtdog]

If you’re talking about the standard “hang outside of the window” type window unit, I don’t think that will work mounted under the bus because you will need to duct a return air as well as the cool air…so effectively you’ll have to build a complex enclosure to circulate the air from inside the bus and ensure that the condenser is exposed to the outside. Also, not sure how effective the fans on window units will be for ducted service… my gut says not very, but could be if ducts are short.

If you’re thinking mini-split units, then disregard the above…

(Post #22 and #34 of my build thread here details what I did with a/c and a window unit.)

 

[Rucker]

I am getting close to installing the HVAC. I realize most of you recommend going with a mini split, but I already have a window units sitting around unused, so it's hard to justify spending the money.

My plan:
Heat - Diesel heater (open to recommendations on which one) ducted to move the heat throughout the bus.
AC - Window unit in back and another in front, I have a third if I really need it.

My question is.......... Is there a reliable way to put the window units under the bus by the diesel heater, and utilize the ducts? I have ample space under the bus, so no concern there.

I am happy to take some jesting for doing things different than you and possibly even stupidly. Most of the digs I have gotten have been humorous to me, but many are also pointless. It is much easier to take the jesting if the reply also includes something constructive.

Thanks

There might be better uses of your time, but I like the idea of repurposing window units.

From a lifecycle design perspective, you'll want to make the enclosure and ducting such that if the window unit fails you can swap in another without major rework.

That diesel heater duct is small area/high velocity whereas the window unit fan is designed for moderate area/moderate velocity. If you have a relatively weak cooling solution venting to the floor, without some really good air circulation you'll have hot ceilings and tepid floors. I'm also not sure how you would get sufficient return air to the unit (to avoid using ambient, probably hot air from the outside instead of somewhat cooled air from the inside).

I recommend if you go this route to build something that can easily be modified so you don't invest a lot of effort only to find your design needs major modifications. I would plan on dedicated ducting straight to the area to cool with an in-line fan to pull the cooled air.

My minisplit in my shuttle bus is mounted right over the bed area in the back, and good thing, too. On a hot day the front of the bus can be 20 degrees warmer than the rear.

I would also ensure space for a future minisplit since they're less than a grand to buy.

 

[cessna175]

I put a 2 zone, 2 ton minisplit in my 24ft. ThomasBuilt/6x6 5 ton military. It will freeze you out in the hot Texas summer, Plus it has a defrost function in the heat mode. It works fantastic!