My HVAC plan - tell me if I'm crazy?

[Salmon]

Somehow I ended up with a bus pretty different than what I thought I wanted in several ways, but most of them are hardly anything to complain about. For instance, one popped up in my search with THREE roof AC units, and a 10kW generator to run them. It also has no windows at all on the left side, two small RV-type windows on the right side, and one small window on the back. And it already has about 1.5" of spray insulation in the roof and sides, and a couple of inches of foam sprayed onto the floor from the underside with 3/4" plywood flooring on top of the metal. The price was acceptable, the timing was right, and AC and generators and spray foam were things I'd planned on eventually probably adding anyway. Long story short, I bought the bus in Colorado, drove my motorcycle out and picked it up, drove to Florida where I registered/titled, etc, and then drove to Maine where I thought I'd be doing the conversion. Along the way, I decided the giant generator was just way too big - it hangs down super low, it uses my precious fuel reserves, it's loud (compared to my dad's EU1000 which I know is an unfair comparison). I also decided I really dislike the 3 roof AC units. For one thing, my bus is a high roof (something like 6'8" standing height aft of the cab and about 6'1" from the driver's seat forward), and I've already crashed my AC units into things I wanted to drive under a few times. I also just think those big white warts on my roof are ugly (as a guy driving around in a skoolie I can't believe I'm even saying that). Despite my aversion to air conditioners and to big generators, I recognize that buses can get pretty hot and there are practical considerations here. So here is my tentative plan - somebody give me some real-world relevant feedback please.

I did my drive from CO to FL over two weeks between July and August. CO on the motorcycle was brutally hot and I expected my time on the bus to be a sufferfest because I wasn't running the generator yet, but to my surprise I was actually quite comfortable with the exception of about 2 days in GA and FL with temps and humidity in mid 90s. The only time that was really unbearable was a couple hours in GA where I sat in traffic on a 2-lane road without moving with the sun beating in through the windshield directly onto me. I found out then that the dash mounted fan didn't work, although blissfully the Red Dot ran with the engine on. I succumbed to my weakness and sat there with the engine running just to power the AC for about 90 minutes.

It got me thinking, maybe I don't even need AC at all. I'm kind of thinking that 95deg and 95% humidity is probably the worst I'll realistically see, and if it's manageable in any better conditions then I should plan for the expected typical more than the least-common fringe cases. Under my expected normal circumstances if the bus gets too hot I can run a fan or just get out of the bus, or just drive the bus somewhere cooler. In the uncommon situation where I "need" to be in the bus and it's super hot, the Red Dot is there in a pinch, although its location is not ideal for anything but driving.

I think I'm going to permanently ditch the two "conventional RV" roof ac units altogether, and also eliminate or severely reduce the size of my generator. I will retain my third roof AC unit, which is a lower profile 12V Red Dot unit of the type you often see on tractor trailer cabs and sometimes on the cab of small box trucks. This one is directly over the cab, which is about 8" lower than the rest of the roofline and visually sort of maintains the roof profile when you look at the bus in...profile. I have a deck hatch off a boat, and two Fantastic Fans for roof ventilation. I haven't finalized my electrical plans yet but I'm assuming that in addition to running AC with the engine on, I will be able to run my 12V, 47A roof AC for short periods (3-5 hours max) off a 300+Ah lithium battery bank (not yet purchased), maybe supplemented by a 2000W generator simultaneously charging the battery bank. I know this is not the ideal AC setup, but keep in mind that I'm thinking this is just a contingency for uncommon fringe situations. I also intend to add more insulation than what I already have. I'm sure there is a point of diminishing returns but I have something like 5 inches to play with for insulation between floor and ceiling, on top of the ~1.5" minimum that's already there. I'll add a couple windows but with only a couple windows to deal with I can afford higher quality with some R-value there, at least better than a normal school bus window would be.

Ok, I think I've laid out my ideas well enough. What do you all think? Is it dumb to think I will be able to just avoid the heat if it gets too much? Is several inches of insulation alone not going to keep a bus cool in the heat? Is my combination of insulation and fringe AC capability not going to do what I hope? Is the forward-mounted AC going to be useless for the rear end of the bus? Is the plan ok but a 20-year-old Red Dot too unreliable? Is it nuts to think any normal future travel partner will be comfortable in these conditions? Please give my plan some constructive critique before I commit.

[musigenesis]

I think the AC thing is just personal taste. I like warm weather and I prefer to have my windows open and get some breeze; I live in the Philly burbs and in my house (which is well shaded) I usually only run the AC for a few days every year. I think as long as I can keep my bus out of direct sunlight, I'll be fine with just using a removable window unit or two as necessary.

But it seems a majority of people prefer to be in an air-conditioned environment. I would have thought living in a school bus would naturally select for people who don't want AC, but it's not the case.

[syntaxterror]

Sitting still is one thing but driving these things get hot particularly the front engine ones.

[cadillackid]

I dont use A/C in my house pretty much except to sleep.. but when im driving i want ice cold A/C in my bus.. if I sit parked somewhere in the bus it turns int oa hot-box quick.. for instance today is 53 out and sunny (in ohio).. I have several windows open because it got so hot in the bus parked working.. out walking I had a hoodie on and if I wasnt doing 15 minute miles id have wanted more.. unless you insulate it superbly a bus is a Hot bix except at night or when its seriously overcast..

[Salmon]

Thanks for the inputs, I guess it's encouraging that nobody has been too adamant that I'm off my rocker.

Originally Posted by cadillackid

if I sit parked somewhere in the bus it turns int oa hot-box quick.. for instance today is 53 out and sunny (in ohio)

Cadillackid I know what you mean, I have had (or had access to) a few conventionally built RVs in the past and it was always surprising how fast they heat up in the sun, even models with a good amount of foam ceiling insulation. This may have been just my sensor needing calibration but even when I picked up my bus and had several days in the high 80s it felt comfortably cooler than outside even for hour-plus rest area stops in noon-ish sun. My bus does have much better insulation than most pre-conversion buses do, but most converted buses must have at least as much as I currently do. My bus is also gloss white and the paint is in very good condition which can't hurt, but plenty of buses have good paint and some have much cooler roof paint. And aside from the cockpit I have only about 9 square feet of window area, half of which is basically limo tinted - so that might be the only feature that is a significant difference from other buses. I am kind of wondering if I realistically can make my bus stay cooler than others tend to if I'm willing to compromise with fewer windows and bulkier insulation. I guess worst case I can wire in a provision for reinstalling one of the roof AC units down the road if I find it unbearable.

Originally Posted by musigenesis

I think the AC thing is just personal taste.

Fair point Musigenesis. While I lived in FL and TX in drafty houses which cost a fortune to keep cool in the summer, we'd usually only use the AC to keep the inside temp under 87 and/or knock the humidity down a little before bed. Even the 87deg limit was more to keep the refrigerator happy than for the people. But plenty of people considered us savages for it. Maybe it's just mentally different to have AC as an available option, vs not having it available at all. Also the showers were more plentiful when I was in a house.

Originally Posted by syntaxterror

Sitting still is one thing but driving these things get hot particularly the front engine ones.

Do you guys have any insulation under the doghouse? My doghouse definitely gets noticeably warm to the touch when I've been driving a while but certainly not hot and it doesn't get hot enough that I can feel it radiating more than an inch or so away. I definitely have heat issues, to the extent that I normally keep the speed under 60 just to maintain reasonable coolant temp and keep the fan from cycling constantly but after experiencing it I'm surprised heat is such a common gripe for FE buses. I have the Cummins 5.9L ISB and my doghouse has insulation 100% covering the underside, but it looks to me like some flimsy factory open-cell foam stuff, not any space age aftermarket insulation blanket that would make it different than anyone else's.

[cadillackid]

Windows - something I absolutely cannot deal without.. even in my house when I had it built all the windows were made larger and a couple added to the original pland that the builder presented to me. at least in a house their solid oak frames and low E glass makes them much more efficient than school bus or RV windows..



I bought a High headroom Bus purposely because i knew the windows were bigger.. an older bus meant no tint (purplosely). my mental function is opposite of a cave dweller.. a fishbowl with lots of light, sun, warmth in winter, and open air in nice weather is necessity or my artist-brain will falter.. thus I couldnt deal with 9 sq feet of windows.. my red bus has factory tint since it came with A/C.. just the difference in those tinted windows.. its a 6 window bus and on the road it A/C's pretty good with its 45-50k BTU system.. (the unit is in back so its a tad warmer in the driver seat).. the DEV bus a 7 window with all clear windows.. I have close to 120k BTU of A/C in it and it keeps me cool in all weather.. this is of course on the road in both busses as rthey only have engine driven A/C.. but its clear to see how you having many less windows than even my red bus can get away with much less A/C...


incidently my Fishbowl bus (1965 GMC) has somewhere around 140-150k BTU of A/C in it.. those busses got their nickname because they are literally made of windows.. only some of the transoms are tinted..

-Christopher

[Salmon]

Ok, thanks for the feedback. That gives me some confidence that at least the differences I'm feeling probably aren't just in my head. I do admire the looks and sense of openness of the buses I see where all the original windows are retained in the conversion. It's not for me - I'd feel like my life is too much on display and I definitely don't want to pay the penalty with cooling and heating requirements. But as far as the aesthetic effect I think I'd appreciate your buses.

[Salmon]

I just saw a video of the Biden-Harris campaign bus for the first time. Politically charged issues aside, the one thing that immediately caught my eye was that I counted five big roof units on that thing! Joe probably would not approve of my AC-less bus plan.

[DWJoyce]

Keep all that high dollar stuff, you don't need to use it, but if you want it, it will be there for you. Also think about the resale.



That 10KW generator is gold.



Watch where you're driving and you won't damage your roof parts.