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Old 06-18-2022, 10:31 AM   #1
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Roof vent or full AC?

Good god I've googled myself to hell and back and I can't get a good grip on what would serve our little bus best. I know cooling is really up to personal comfort at the end of the day, but here we are. We have a super short 5 window bus - dash AC not running right now but I doubt it would do us too much good if it was. This is a weekend rig out in Missouri where it gets over 100 in summer and my partner wants to see the desert, so we need something to keep us under 80 degrees. My gut tells me AC is the way to go, and I was thinking a 6000btu window unit + 200w of solar + 3-400w of battery bank. However, I'm second guessing because everyone raves about roof fans and shade doing wonders. What's the move? Am I wildly off with my numbers above? Help!

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Old 06-18-2022, 11:18 AM   #2
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search on here about running A/C on solar.
it can be done done but not with the system you just named.
i think in full shade a 6000 btu unit would struggle.
i am building a 5 window for my wife and am fixing the dash air as we speak and will be installing a 9000 btu mini split for use with shore power or genny when parked.
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Old 06-18-2022, 11:38 AM   #3
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search on here about running A/C on solar.
it can be done done but not with the system you just named.
i think in full shade a 6000 btu unit would struggle.
i am building a 5 window for my wife and am fixing the dash air as we speak and will be installing a 9000 btu mini split for use with shore power or genny when parked.
It's likely that we'll have shore power when camping normally, but there sure isn't any shore power out in the desert. Maybe we'll swing for a generator.
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Old 06-18-2022, 11:53 AM   #4
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Originally Posted by weirdlittlebus View Post
This is a weekend rig out in Missouri where it gets over 100 in summer and my partner wants to see the desert, so we need something to keep us under 80 degrees. My gut tells me AC is the way to go, and I was thinking a 6000btu window unit + 200w of solar + 3-400w of battery bank. However, I'm second guessing because everyone raves about roof fans and shade doing wonders. What's the move? Am I wildly off with my numbers above? Help!
Hate to be the bearer of bad news, but yes, you're a bit off on the numbers.

Quick google search & it looks like most 6KBTU window A/Cs will draw around 500-600W if not more.

If your bus is uninsulated or poorly insulated, in 100+ degree temps, in full sunshine (which you'll have to be in since your solar panels depend on it, assuming they're roof-mounted), you're going to be pretty much running that A/C constantly to stay cool. Even then, a 20+-degree delta (100+ to 80) might not even be doable depending on the totality of things. But let's say it is...

You've got 500-600W of consumption, pretty much 24 hours / day if you want to stay comfy. But you've only got 200W of production - absolute max. Before accounting for the unescapable system losses your system will incur, and the fact you'll rarely be seeing 200+W being harvested, you're only producing 1/3 of what you use. Just to run the A/C and nothing else. And most importantly, only when the sun is shining. Without changing things, your system is unsustainable.

400W of battery bank... that's less than 1 hour of run-time before being discharged to absolute zero (which you'd never want to attempt). But you could double that 400W bank capacity, or triple it, or even quadruple it, and it still wouldn't get you to the point where you could reliably run A/C off-grid for any extended length of time without inputing significantly more energy. Maybe you even meant Amp Hours instead of Watts... 400AH of lithium @ 80% discharge would give you a bit over 6 hours of runtime. So you might make it through part of a day, or maybe even a whole day if you opt to sweat a bit, but past that you're no better off, with a dead battery you have no (free) way to charge.

There do exist people here who run A/C purely off solar. But the system you'd have to build to make it work needs to be fairly expansive (and expensive). I haven't done the math but I imagine you'd need to pretty much cover your entire roof surface with panels to support A/C off-grid + other stuff in a 5-window bus.

We have A/C, but it's only doable long-term when we're hooked up to shore power. We can run off a gennie, but fuel consumption limits that to emergency / short-term situations. The most practical approach for most people seems to be staying away from hot places during the summertime, while using ventilation fans to keep air moving in temperate locations.

As far as staying in a bus without A/C (only fans) during 100+ degree temps... that wouldn't result in anything I'd consider to be a relaxing vacation.
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Old 06-18-2022, 01:00 PM   #5
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Fix the dash ac

Then consider what to add from there.

I am in Kansas and go west and south. I think you’re going to want that dash air workin
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Old 06-18-2022, 01:19 PM   #6
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Then consider what to add from there.

I am in Kansas and go west and south. I think you’re going to want that dash air workin
fix the dash A/C yes.
hope the OP is capable.
replacing the entire system is not quick or easy and definitely a not a one day job even if you know what you are doing.
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Old 06-18-2022, 02:06 PM   #7
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yep fix the dashboard A/C.. and plan on a generator... if you are camping in the desert away from people then running a portable inverter generator wont matter.. a 6k BTU A/C in the sun wont touch even a short bus in full sun unless you Super-insulate it. in the shade you can make a go of it... (is there such thing as shade in the desert?)..


when driving your 6k BTU unit wont even touch the bus.. if you both sit up front and put up a shower curtain behind the seats your dash unit will keep you nice N cool... the bus will boil.. the 6K and dash A/C together could make a go of it keeping the whole bus cool on the road if you cover all the windows and make it a cave in the back.. (hard to enjoy sight-seeing with the windows covered)..



6K window unit at night will do really well at cooling the entire bus even on warm humid nights if you ever camp in humid areas. . in the dry desert it will have an easy time at night and you'll be as cool as you like...
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Old 06-18-2022, 02:54 PM   #8
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for me in the desert?
the ones i have spent time in overseas are hot as hell during the day and in the 60's at night
because of the work i do and my children work for me now and have come back to the nest we only run our house at 79.
its hard to walk in a cold house after a hot day.
i like to set in a shade for a few before i walk in an A/C house but i do it for a living and if its working then why am i there.
i moved on to the several that aint?
same thing in the winter? if the hest is working then i go to the one where it isnt working.
not talking about houses stuff?
commercial like hotel motel and hotel there is a difference if you care.
i am mainly govt work but i get stupid mess out in town sometimes with a general contractor by name and you have to befriend the electrician yourself to at least let him know that the equipment is speced 460 and they are only providing 280 and sparky says he can make it work?
yes that is the problems we talk about here.
no problem on my govt jobs but get out in town.
aint even an electrician but i can call BS/sorry question things.
where this relates to us is bootleg grounds.
you dont know whatever campground you go to and you dont know if they have clean or dirty power?
if you want advice on how to check and what you need to check please ask
electricity is not the one to play with if you dont know.
even my first bus at 24v hurt me in the battery box and i have been stupid and got 230 and 460 actually cranked up in the transformormer to 510
never new there was a dial in there?
kinda cool but kinda scary.
average person aint gonna do that?
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Old 06-18-2022, 03:21 PM   #9
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fix the dash A/C yes.
hope the OP is capable.
replacing the entire system is not quick or easy and definitely a not a one day job even if you know what you are doing.
We fully intend to fix the dash AC, no worries there. It's a pressure switch, and the system is fine otherwise I've been told. Really just mentioned that it isn't working because I thought someone would ask.
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Old 06-18-2022, 03:24 PM   #10
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yep fix the dashboard A/C.. and plan on a generator... if you are camping in the desert away from people then running a portable inverter generator wont matter.. a 6k BTU A/C in the sun wont touch even a short bus in full sun unless you Super-insulate it. in the shade you can make a go of it... (is there such thing as shade in the desert?)..


when driving your 6k BTU unit wont even touch the bus.. if you both sit up front and put up a shower curtain behind the seats your dash unit will keep you nice N cool... the bus will boil.. the 6K and dash A/C together could make a go of it keeping the whole bus cool on the road if you cover all the windows and make it a cave in the back.. (hard to enjoy sight-seeing with the windows covered)..



6K window unit at night will do really well at cooling the entire bus even on warm humid nights if you ever camp in humid areas. . in the dry desert it will have an easy time at night and you'll be as cool as you like...
Great tip about closing up the front! It sounds like a just in case generator or shore power is the only way to go. Makes sense, but it's easy to be hopeful. I'm not scared of being hot though.
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Old 06-18-2022, 03:33 PM   #11
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Hate to be the bearer of bad news, but yes, you're a bit off on the numbers.
...
As far as staying in a bus without A/C (only fans) during 100+ degree temps... that wouldn't result in anything I'd consider to be a relaxing vacation.
I'd rather get bad news now than after I spent the money! I had a feeling it wasn't doable, but thought maybe there's some trick to keeping cool I was missing. Turns out the trick is probably just to stay away from the heat, which I don't mind. To be honest, my brain is fried after all the bus research I can stomach and all those numbers were really running together. I probably need a break.

As far as the desert.. My fiancé is hell bent on seeing it, so maybe an rv park with shore power and a ride out is the way to go. That's more of a vacation I'd like to be on.
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Old 06-18-2022, 04:51 PM   #12
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I'd rather get bad news now than after I spent the money! I had a feeling it wasn't doable, but thought maybe there's some trick to keeping cool I was missing. Turns out the trick is probably just to stay away from the heat, which I don't mind. To be honest, my brain is fried after all the bus research I can stomach and all those numbers were really running together. I probably need a break.

As far as the desert.. My fiancé is hell bent on seeing it, so maybe an rv park with shore power and a ride out is the way to go. That's more of a vacation I'd like to be on.

we did ther deserts as kids.. death valley in july in our Black IH scout... my dad always had to take us west.. always had to go to the desert in July.. easy for him to say when mom and him sat upfront which was the only cool place in that scout... then there was the time dad thought it would be fun to shut off the A/C and roll the windows down.. you know so that 125 degree air could blow on us in the back-seat and unbutton our shirts and drink water... yeah we werent allowed to take our T-shirts off (and of course mom couldnt either)... I whined and carried on so much so that just maybe I could be lucky and next year I could be so lucky to get left at home.. bada bing!! i was so lucky to never have to go on one of those journies again..



the next time i visited death valley was in my own Jeep with an A/C that I had modified...



now back to the desert.. some deserts cool down nicely at night but many dont... death valley got down to about 95 at night in summer as it was in a valley that held the heat.....



you also dont have to go to the desert in the summer.. deserts are very beautiful in winter.. many times this is when the cactii flower and the weather is temperate.. you may very well be using Heat at night and not need any A/C in the day....


there are also differenbt deserts.. I enjoyed visiting some of the ones that were a bit more tempered like arches and canyonlands national parks.. alot of it is jeep style off-roading, however there are lot of neat places to see in those parks without a 4WD...



A/C wise I do often find myself in Hot places in the summer.. and while I enjoy being outside and walking or sitting at a coffee-shop or in a park in summer heat... I really hate to drive a bus in the heat.. or even a car if im on an interstate.. the engine heat from a bus can be fierce.. esp wit hthe windows open where the mirrors pull a negative pressure and cause more air to be sucked in from the engine doghouse (more heat).. so all of my busses are Air-conditioned.. (yes I even recently added driver A/C to my 45 year old bus)...it makes my trip much more enjoyable to be able to choose being nice N cool on the road... I dont always use it.. sometimes I have the window open for fresh air and the A/C blasting so I dont melt....
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Old 06-18-2022, 05:00 PM   #13
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we did ther deserts as kids.. death valley in july in our Black IH scout... my dad always had to take us west.. always had to go to the desert in July.. easy for him to say when mom and him sat upfront which was the only cool place in that scout... then there was the time dad thought it would be fun to shut off the A/C and roll the windows down.. you know so that 125 degree air could blow on us in the back-seat and unbutton our shirts and drink water... yeah we werent allowed to take our T-shirts off (and of course mom couldnt either)... I whined and carried on so much so that just maybe I could be lucky and next year I could be so lucky to get left at home.. bada bing!! i was so lucky to never have to go on one of those journies again..



the next time i visited death valley was in my own Jeep with an A/C that I had modified...



now back to the desert.. some deserts cool down nicely at night but many dont... death valley got down to about 95 at night in summer as it was in a valley that held the heat.....



you also dont have to go to the desert in the summer.. deserts are very beautiful in winter.. many times this is when the cactii flower and the weather is temperate.. you may very well be using Heat at night and not need any A/C in the day....


there are also differenbt deserts.. I enjoyed visiting some of the ones that were a bit more tempered like arches and canyonlands national parks.. alot of it is jeep style off-roading, however there are lot of neat places to see in those parks without a 4WD...



A/C wise I do often find myself in Hot places in the summer.. and while I enjoy being outside and walking or sitting at a coffee-shop or in a park in summer heat... I really hate to drive a bus in the heat.. or even a car if im on an interstate.. the engine heat from a bus can be fierce.. esp wit hthe windows open where the mirrors pull a negative pressure and cause more air to be sucked in from the engine doghouse (more heat).. so all of my busses are Air-conditioned.. (yes I even recently added driver A/C to my 45 year old bus)...it makes my trip much more enjoyable to be able to choose being nice N cool on the road... I dont always use it.. sometimes I have the window open for fresh air and the A/C blasting so I dont melt....
Our bus is a '91 so exactly 30 years old this October and just by the look of the vents available I have a feeling the dash AC is gonna leave us pretty warm. It's better than nothing!!! The bus does have wing windows though and there's nothing like a wing window. Flat windows just don't do it like a wing window does.

Winter might be a good move. I can't imagine we'd ever try it during summer with or without AC. The bus heat runs great, so maybe we'll plan a winter trip to Arizona this year. That might be great. Thanks for the insight!
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Old 06-18-2022, 05:34 PM   #14
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We have a 7 windows and a 5000 btus window unit above the rear door. We have no dash ac. We have done some trips in coastal NC in 90 deg temp and 80% humidity. We have a 400w AGM battery bank and 800w solar. We run the ac about 6 or 7h on batteries at night with no issue. Our Bed is in the rear, below the ac. Ac keeps us comfortably at about 75. Beside ac, we run a 12v fridge and charge phones. That is it. It works. During the day on the road is ok with windows opened and roof hatch opened.
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Old 06-18-2022, 07:32 PM   #15
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As far as the desert.. My fiancé is hell bent on seeing it, so maybe an rv park with shore power and a ride out is the way to go. That's more of a vacation I'd like to be on.

We have winters here too. You could wait for one
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Old 06-18-2022, 09:55 PM   #16
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We have a 7 windows and a 5000 btus window unit above the rear door. We have no dash ac. We have done some trips in coastal NC in 90 deg temp and 80% humidity. We have a 400w AGM battery bank and 800w solar. We run the ac about 6 or 7h on batteries at night with no issue. Our Bed is in the rear, below the ac. Ac keeps us comfortably at about 75. Beside ac, we run a 12v fridge and charge phones. That is it. It works. During the day on the road is ok with windows opened and roof hatch opened.
Okay, that's reasonable to shoot for if I piece it together over time. That's super helpful, thanks a lot.
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Old 06-22-2022, 08:36 PM   #17
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AC thoughts

I am new to the Skoolie Universe and still working on my build. I have a 34foot Thomas and put a 13,500 btu roof mount AC. I realistically needed 2 units but I wanted to keep my emergency hatches. I use a 4600W dual fuel rv generator fir running AC while driving and then shore power can take over if available.mini splits also seem popular so I think the Solar route will be costly to handle your requirements.
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Old 06-22-2022, 09:44 PM   #18
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How well is the dual fuel ac working?

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Originally Posted by Mat7783 View Post
I am new to the Skoolie Universe and still working on my build. I have a 34foot Thomas and put a 13,500 btu roof mount AC. I realistically needed 2 units but I wanted to keep my emergency hatches. I use a 4600W dual fuel rv generator fir running AC while driving and then shore power can take over if available.mini splits also seem popular so I think the Solar route will be costly to handle your requirements.
We installed a 120v/ 15k btu rooftop hvac, before the demo was complete, to battle the FL heat. In the shade (no insulation) it's only cool-ish.

-How does your ac fair en route?

-Fuel consumption during a June afternoon?
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Old 06-23-2022, 11:10 AM   #19
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We have a 6000 btu window AC in our 5 window shorty and after market AC in the dash. The bus is well insulated and has dual pane windows as well as a barrier behind the drivers/passenger seating area. We don't use the window AC when driving.

Here is what we've learned. The dash AC with the partition installed can get too cold in 100 degree weather--can't complain about that. On the other hand, the window unit works hard to just barely provide a 10 to 12 degree drop in interior temps after the outside air reaches 90 degrees and ONLY if we leave the roof vents open to vent hot air. Without the open vents the interior of the bus turns into a sauna in about a minute. This all in full sun. When dry camping we use a 3000 watt Yamaha inverter generator. It is capable of operating the AC and our microwave at the same time but labors if we add the house battery charger at the same time (Green Acres anyone?)
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Old 06-23-2022, 12:04 PM   #20
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the partition is the big thing for dash A/C.. it was amazing just how much cooler it was in my DEV bus when I hung up a clear plastic shower curtain behind my work area vs not... on really hot days my dash air and mid unit blew cold air on and around me but there was still lots of heat.. with the simple curtains hung with magnets it made my "cab" much more comfortable.. obviously the ultimate was when I installed a rear Bus A/C unit.. that bus is fully stock interior.. stock windows, stock door, stock floors walls and ceiling.. non tinted windows...



my dev bus will stay in the low-mid 70s now in 100 degree humid heat.... even gets cold in there if the humidity lowers a bit..

ol trunt's partition is the real deal! nicely done!...


I am impressed with the high capacity Dash unit I put in my Superior... it technically was not sold as an underdash A/C, however it fit (after I fabbed my own mounts).. and it looks vintage.. and it blows LOTS of cold air.. thats a full size bus and theres really no room for me to mount a second compressor so its going to stay a dash A/C only bus..


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