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Old 05-19-2017, 09:59 PM   #21
Bus Geek
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,927
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
The real beauty of mini splits is they are true variable speed.. the fans and compressor . So on days when you don't need the capacity the unit doesn't cycle on off on off et. It simply slows itself down and pulls less power of course when it does.. the result is that when the sunload drops shortly after so does the heat load on the bus.. the unit will make setpoint and slow down .. they will cycle when you reach minimum and still are lowerIng the temp but when it needs to cool again it will start out at the lowest speed and ramp as needed..
bus window heat is real.. my carpenter bus has non tinted windows and bam when sun hits instant heat..
my BlueBird has Factory Tint and wow amazing difference..
some reflective curtains that you can close on one side at a time as the sun moves might help and still giv you nice daylight inside from the shaded side..

Good insulation surely helps over Factory and the fact you are parked...

Just for reference a stock school bus built with factory air cond for driving will have 100K or more in a full size 12 row bus..

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Old 05-20-2017, 05:57 AM   #22
Bus Nut
superdave's Avatar
Join Date: Mar 2015
Location: hills of sw virginia
Posts: 889
Year: 1996
Chassis: thomas
Engine: 8.3 cummins
Rated Cap: 11 window
do you have any awnings installed to shade your windows? do your windows and door seal well, air exchange makes it even harder to cool. I had curtains made that have a white backing.
living in a bus down by the river.
my build pics
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Old 05-20-2017, 07:28 PM   #23
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warewolff's Avatar
Join Date: Sep 2016
Location: NY
Posts: 487
Year: 2000
Coachwork: Carpenter
Chassis: International 3800
Engine: T444E
Originally Posted by superdave View Post
do you have any awnings installed to shade your windows? do your windows and door seal well, air exchange makes it even harder to cool. I had curtains made that have a white backing.
No awning. I had planned on using R7 foamular inserts in the window frames, wrapped in mylar to reflect the sun when the windows aren't in use. I haven't framed the windows yet, though.
Roads? Where we're going, we don't need ... roads.
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Old 05-22-2017, 09:28 PM   #24
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Join Date: Apr 2012
Location: So Cal
Posts: 3,233
Year: 1935
Coachwork: Superior
Chassis: Chevy
Engine: 317 ci/tid / Isuzu
My tiny bus has 2" of foam insulation top, bottom and sides and double glazed windows except for the windshield. Based on simple calculations, a 6K ac unit should have been enough to cool the interior from 105 degrees F to at least 85 degrees. The test of this came on an asphalt parking lot at a Camping World in Bakersfield, Ca. in July. The asphalt was 117 degrees and the air temp was 107 and the sun had begun to set. We smugly closed up the bus, pulled the reflective window shades, flipped on the ac and waited for the bus to cool down--it didn't, rather it turned into a sauna. Dripping with sweat I told my wife that I thought I must have miscalculated the ac requirements when it struck me that if I opened the two small zippered windows in the pop top, it might help. It did, and within 15 minutes the interior had dropped to 85 degrees and finally to 80 degrees after a bit more time.

I guess the point here is that you need as much ac as you can support and a mechanical way to rid your bus of the hot air that gathers near the roof.

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Old 06-03-2017, 12:22 PM   #25
RC000E's Avatar
Join Date: Feb 2015
Location: Las Vegas, NV
Posts: 159
Year: 2001
Coachwork: Ford
Chassis: E450 #Vanlife
Engine: 7.3 Powerstroke
Rated Cap: 25
Originally Posted by warewolff View Post
Thank you. Really appreciate the response. It helps to know you are running a 21 SEER unit. If you don't mind my asking, have you ever checked the specs on your units to see what the manufacturer says the max wattage consumption is? Then you can compare that with what you're actually seeing and put an end to my obsession. I'd be curious to know if the specs are actually inaccurate, low balling, or if maybe the units are little more efficient today.

My bus is pretty heavily insulated now with 1 1/2" through all the walls and floors but I think what's happening is the sun is beating down through the remaining windows (I've got 6 in the front open and 2 in the rear), heating up the bus like a greenhouse as the heat can't escape through the insulation. Adding insult to injury, the compressor on my fridge is blowing hot air, the 12 solar panels are absorbing heat that I would assume is transferring into the roof at least a little, and the charge controller/inverter/battery array are giving off heat. Temp today was 98 degrees in the bus. I couldn't even work. This is with reflective elastometric roof paint too. Once I frame the windows I'm going to design window inserts to reflect the sunlight / insulate the bus, but that's a few weeks down the road. Hopefully that will help a lot.

I think I will spring for the 12k unit. Maybe we can meet up sometime and you can share these hacks with me. I might have to add another set of batteries in series but I think I'm close to being able to handle leaving the a/c on all the time. Worst case scenario I can set it to the low setting and close the bedroom door. Voila, problem solved. While I definitely have the headroom on my inverter I am just worried about topping the batteries off before night time. Pulling a 1kWh load with a total available incoming of less than 1.2kWh is like trickle charging an 860aH battery bank.

Anyway, thanks. I'm going to buy the 12k unit and see how it goes.
Sub'd to this thread. Looking forward to updates when you have them.
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Old 08-22-2017, 07:06 AM   #26
Join Date: Feb 2017
Location: Baltimore, MD
Posts: 64
Year: 1995
Engine: 12 valve 8.3L Cummins
Did you buy this Toshiba?
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