Window A/C Power

[PNW_Steve]

From personal experience....

My first bus had RV windows and 1-1/2" - 2" of spray foam insulation. I had two 12,500 BTU roof airs and an 8kw diesel generator to run them.

I made the mistake of removing the bus air during conversion.

Running down the highway in 90F weather, with both roof airs running, I cooked in the drivers seat. The back of the bus but as bearable but driving kinda sucked in warm weather.

Driver fans did help some.

Good luck with your project.

[Tango]

Time to install some directed ducting.

[o1marc]

IMHO a 5k BTU window unit would only be effective if your chair is parked right in front of it.

[Tango]

I started out with a 5K but moved up to a high efficiency 8K. My interior is so small that when I tested it out on a 100+ degree day it got quite chilly inside in no time at all. Granted, the bus was NOT parked in the sun, but I remain hopeful it will be adequate given the addition of a roof rack (aka; shade), Low E glass , double pane windows and minor insulation (it had zero at the time).



One of the few advantages of a really small space (about 500 cf). They are relatively easy to heat & cool.

[o1marc]

Originally Posted by Tango

I started out with a 5K but moved up to a high efficiency 8K. My interior is so small that when I tested it out on a 100+ degree day it got quite chilly inside in no time at all. Granted, the bus was NOT parked in the sun, but I remain hopeful it will be adequate given the addition of a roof rack (aka; shade), Low E glass , double pane windows and minor insulation (it had zero at the time).



One of the few advantages of a really small space (about 500 cf). They are relatively easy to heat & cool.

I figure my bus is close to 1800cf. Gonna need something much bigger than 5k.

[Tango]

Roger that. Probably four times what I need. Cadillac can probably provide the proper calculations.

[Fjatheart]

Originally Posted by john61ct

Can always partition off part of the space to lower temps and energy usage.

"Cold" in hot Texas days is a big ask, hope you're plugging into shore power when stationary, or that's going to be a very expensive setup.

Yep, originally stated, that is the plan. Shore power when stopped.

No real answers here....

[Fjatheart]

Originally Posted by Tango

I started out with a 5K but moved up to a high efficiency 8K. My interior is so small that when I tested it out on a 100+ degree day it got quite chilly inside in no time at all. Granted, the bus was NOT parked in the sun, but I remain hopeful it will be adequate given the addition of a roof rack (aka; shade), Low E glass , double pane windows and minor insulation (it had zero at the time).



One of the few advantages of a really small space (about 500 cf). They are relatively easy to heat & cool.

This is helpful. What size bus? How many windows?

[Tango]

Tiny old dog nosed 1946 Chevy/Wayne. 21' bumper to bumper. Originally 3-3/4 windows...now 2-3/4 windows.



Started off looking like this...



...but at the moment looks like this. Still a ways to go after seven years.

[Booyah45828]

I doubt a 5k btu unit is going to work. I doubt a 15k btu unit would work.

Your average passenger car ac has what roughly equates to a 40k btu. I'd imagine the dual system you removed likely provided double that or more. Those systems are designed to take a parked vehicle on a hot day and make it comfortable in a few minutes.

You're not going to recreate that system with window units.

Yes, your insulation and window upgrades will help, but not much in the grand scheme of things. You'd have to have the rear unit running full time in order to maintain the temp, which isn't likely to happen.

If you are still interested in trying it, I'd use a 15k btu unit(either rooftop or window) and a 3kw inverter. I would definitely have the power system isolated from the vehicle battery. You'll have to run a dual alternator setup, unless you can get a 250+ amp single alternator. Even with a dual setup, 3kw is a lot of amperage at 12v, so size every accordingly.

[Fjatheart]

Originally Posted by Booyah45828

I doubt a 5k btu unit is going to work. I doubt a 15k btu unit would work.

Your average passenger car ac has what roughly equates to a 40k btu. I'd imagine the dual system you removed likely provided double that or more. Those systems are designed to take a parked vehicle on a hot day and make it comfortable in a few minutes.

You're not going to recreate that system with window units.

Yes, your insulation and window upgrades will help, but not much in the grand scheme of things. You'd have to have the rear unit running full time in order to maintain the temp, which isn't likely to happen.

If you are still interested in trying it, I'd use a 15k btu unit(either rooftop or window) and a 3kw inverter. I would definitely have the power system isolated from the vehicle battery. You'll have to run a dual alternator setup, unless you can get a 250+ amp single alternator. Even with a dual setup, 3kw is a lot of amperage at 12v, so size every accordingly.

Buzzkill!

The aux A/C that was removed didn’t do anything but blow hot air and had to be recharged once a year. It was also not set-up to run off shore power, so it didn’t make sense to keep it or spend anymore on it. It also took up a lot of space.

Maybe I should consider only running whatever I get from the generator and avoid a dedicated inverter and battery bank for road air. I would need a generator for running the A/C when parked anyway. Seems like what I would spend in time and money for an alternator, batteries and a 3k inverter, I should go with something more like a Honda 3k generator to run a larger A/C.

[Booyah45828]

Originally Posted by Fjatheart

Maybe I should consider only running whatever I get from the generator and avoid a dedicated inverter and battery bank for road air. I would need a generator for running the A/C when parked anyway. Seems like what I would spend in time and money for an alternator, batteries and a 3k inverter, I should go with something more like a Honda 3k generator to run a larger A/C.

That's what I would do.

Putting a curtain behind the driver/passenger seat should make enough of a compartment for you to be comfortable up front while going down the road.

Then, while stopped, use shore power/generator to keep the whole thing cooled. You're rear section won't cool off immediately this way, maybe in an hour or so. But this way is actually doable.

[Fjatheart]

Originally Posted by Booyah45828

That's what I would do.

Putting a curtain behind the driver/passenger seat should make enough of a compartment for you to be comfortable up front while going down the road.

Then, while stopped, use shore power/generator to keep the whole thing cooled. You're rear section won't cool off immediately this way, maybe in an hour or so. But this way is actually doable.

Is that a bad idea to run the generator to power the AC when driving?

[o1marc]

Originally Posted by Fjatheart

Is that a bad idea to run the generator to power the AC when driving?

No, what are your concerns?

[PNW_Steve]

Originally Posted by Fjatheart

Is that a bad idea to run the generator to power the AC when driving?

I sure hope not..... I have run my generators while driving, to run a/c, over tens of thousands of miles.


As long as it is properly installed your generator should be fine. Staying cool in the drivers seat may still be challenging though.


I remember one particular drive through Amarillo in August. Headed West on I-40 late afternoon. It was about 115F outside and the sun was in my face.

I had the generator cranked up and both roof airs running on high.

I was wearing a pair of shorts and nothing else. I had sweat running down my face, chest & back.

I started wondering if there was any to reinstall the road air.

[o1marc]

Originally Posted by PNW_Steve

I sure hope not..... I have run my generators while driving, to run a/c, over tens of thousands of miles.


As long as it is properly installed your generator should be fine. Staying cool in the drivers seat may still be challenging though.


I remember one particular drive through Amarillo in August. Headed West on I-40 late afternoon. It was about 115F outside and the sun was in my face.

I had the generator cranked up and both roof airs running on high.

I was wearing a pair of shorts and nothing else. I had sweat running down my face, chest & back.

I started wondering if there was any to reinstall the road air.

Does your bus not have fans mounted on the windshield. Mine has dual 2 speed fans that helps tremendously when it's hot.

[PNW_Steve]

Originally Posted by o1marc

Does your bus not have fans mounted on the windshield. Mine has dual 2 speed fans that helps tremendously when it's hot.

Yes, the drivers fans do help but not nearly enough to be even close to comfortable.

Driving West on an August afternoon, I felt like an ant under a magnifying glass.

[Fjatheart]

Originally Posted by o1marc

No, what are your concerns?

Still learning and trying to ask all the questions. Sounding more and more like a costly endeavor to keep cool. I had hoped with a 6 window cutaway with half of the windows sheeted over, 2 inches of spray foam (ceiling, walls and floor) and a healthy dash air I would be able to run a 2k to 3k Honda gen and run something under 15k btu when on the road and when parked. Sounds like that won’t come close.

[david.dgeorge07]

Originally Posted by Fjatheart

Is that a bad idea to run the generator to power the AC when driving?

I do it all the time.

[david.dgeorge07]

My front mini split (12k BTU) is right above my windshield and it does make the driver cooler, even nice and cool in many situations, not so much the rest of the space.

It is kind of either encouraging or depressing how simply opening a bunch of windows will get you the most comfortable in most summer driving conditions.

It takes a huge amount of cooling while you’re driving to come close to the comfort level of just opening things up and getting strong air flow.

Parked is a different story. AC helps a ton when camped.