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Old 07-12-2018, 03:07 AM   #1
jon
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Default Roof top air conditioner efficient enough to run from alternator/inverter.

I hope I said that right. I just ordered a Transit to be converted into our next RV and we seem to do a lot of traveling and weekend camping so I won't have a large lithium battery bank. Probably 300ah. I can't remember how may amps my Sprinter 220 amp alternator supplies to the house batteries, but I don't think it's enough to keep up with a standard 13000 BTU typical RV roof air conditioner.
I want to get a Kingtec 12 volt rooftop AC (like the one Outside Van installs) but I can't find any reviews and I don't trust their claim of 13000 BTUs with only 45 amps at 12v. does anyone have any info?
Thanks,
Jon
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Old 07-13-2018, 04:51 PM   #2
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Default ARV

Another option would be to investigate the efficient A/C that Advanced RV installs on their vans (they'll also apparently retrofit it on other brands). I believe the unit is mfg. in Australia.

https://advanced-rv.com/quiet-air-co...tall-retrofit/
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Old 07-13-2018, 05:56 PM   #3
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Another option would be to investigate the efficient A/C that Advanced RV installs on their vans (they'll also apparently retrofit it on other brands). I believe the unit is mfg. in Australia.
Thanks. I've looked into that also, but I don't really want to take my van up to Ohio for a couple days. I might just have wiring that'll support up to 80 amps pre-wired to a vent for now. That way I can choose whatever later on.
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Old 07-22-2018, 11:31 PM   #4
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After finding that the Airstream Interstate 13,500 BTU rear A/C could not keep the van cool traveling down the road, I had a 48,000 BTU engine driven unit installed in my Transit conversion for the rear. We just returned from a trip to the beach down by Galveston, Texas and the van had no problem keeping a comfortable temperature throughout. The Airstream would have been like a sauna with the exterior temperatures that we were experiencing. No matter which way you decide to go, make sure that your van is well-insulated because that can make a big difference and how much A/C capacity you need.
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Old 07-23-2018, 12:05 PM   #5
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After finding that the Airstream Interstate 13,500 BTU rear A/C could not keep the van cool traveling down the road, I had a 48,000 BTU engine driven unit installed in my Transit conversion for the rear. We just returned from a trip to the beach down by Galveston, Texas and the van had no problem keeping a comfortable temperature throughout. The Airstream would have been like a sauna with the exterior temperatures that we were experiencing. No matter which way you decide to go, make sure that your van is well-insulated because that can make a big difference and how much A/C capacity you need.
Didnít the dashboard air-conditioner keep the van cool while you were driving down the road? I just recently found out after doing only a little bit of research that dashboard air-conditioners are extremely powerful and a high B to youÖ Because people who get in their cars want air-conditioning fast and cold. For example, the promaster has 42,000 BTU air conditioner under the hood. Meaning, when you turn your dashboard a/c and you are driving at highway speed or around town, you have 42,000 BTU of air-conditioning blowing out of the dashbord. I found that almost impossible to believe until somebody brought to my attention that after 5 or 10 minutes, most people turn their air conditioning down from all the way up to something much lower and more comfortable because even in the hottest of climbers, your dashboard air-conditioner can frost your windows on the inside because there are so powerful!
I spoke with somebody at FCA and they confirmed this. They did say however, that if somebody IDLES their van for air conditioning to stay comfortable at night while camping etc. the air conditioner runs at about 20,000 to 22,000 BTUs. That is still not bad. I have found that a lot of people have used one of or both of the floor vents and ducted them to Bring the air-conditioning directly to the back living area of the van. I did the same thing. It works. I can idol the van, run the air conditioner with just the passenger side floor vent ducted and sent into the back of the van, and it keeps the van cold, and it gets cold pretty quickly. Although, I blocked off the driver side, and I have found that using just the passenger side itís really best to only put the fan up about 3/4 of the way because so much air is being forced out, and I have blocked out half of itís exit points. So for fear of although, I blocked off the driver side, and I have found that using just the passenger side itís really best to only put the fan up about 3/4 of the way because so much air is being forced out, and I have blocked out half of itís exit points. So for fear of putting unnecessary wear and tear on the fan, the pump, blower, I have only turned the fan up 3/4. I only tested this out for 30 minutes and the van was freezing cold after that time. It was sunny and 80į outside, I had the windshield and driver side and passenger side windows covered with shields made with reflectix, and I have no windows. However, my Sportsmobile top was up and has virtually no insulation, so heat did build up in the sleeping loft until I climbed the ladder and unzipped the tops of each of the five windows to let the heat escape. I have yet to try this while actually sleeping up there with the ducting running up to the sleeping loft while I am sleeping during a hard day or night Ė like I will be in Slab City next week. Now if that isnít a good test, I donít know what is. It is 80 to 90į at night right now down there, and the sun comes up early and immediately lasts the loft canvas with heat. So, we will see. I will report back and let you know how it does. .
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Old 07-23-2018, 04:53 PM   #6
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I was referring to a small rooftop AC to keep passengers riding on the rear seat cool. My Sprinter dash AC worked fine at keeping the first few rows of passengers cool, but I didn't have any in the very back. I want to be able to turn on the rear AC without it draining my house batteries.
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Old 07-24-2018, 01:26 AM   #7
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If the ambient temperature was below 85 degrees and I pre-cooled the van before setting out, the two A/C units together could keep the van comfortable. When the temperature is outside got above 85 and the van had 8 people in it, the rear of the van became uncomfortable. Part of the problem in my Interstate was the fact that the Dometic rooftop unit could only produce a 17įF drop across the evaporator. Dometic claimed it should be at least 21įF drop. The other part of the problem was that Airstream doesn't do a very good job of insulating the van.
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Old 08-16-2018, 12:27 AM   #8
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Originally Posted by dhuff View Post
Another option would be to investigate the efficient A/C that Advanced RV installs on their vans (they'll also apparently retrofit it on other brands). I believe the unit is mfg. in Australia.

https://advanced-rv.com/quiet-air-co...tall-retrofit/
Advanced RV sent me a spec sheet on the Quiet AC. It said that it was rated at 14a@120v. That is too much for me.

I was reading about the Colman Mach 3 PS, 13500 BTUs, 11.2a@120v. The only problem is that it's 13 inches tall.
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Old 08-16-2018, 04:34 AM   #9
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Default Mach 10 Soft Start

The Mach 10 with Soft Start is probably what all RV manufacturers who are building to run a/c units off of battery/salary/inverter setups, will start to use. Nothing fancy, just good old American advancements in technology.

Right now I am using a 3000W inverter to run my portable a/c unit in my van (hidden in a closet, of cours, and directly out of the side of the van) in conjunction with 366ah Deep Cycle Batteries and 300W of flexible solar on the roof of the fiberglass Sportsmobile poptop. I have 2 solid hours of a/c without any sun (just full batteries) and that should go up to about almost 4 hours with sun and the addition of one more battery. Not bad for self build. . I only charge my batteries via solar, no alternator charging. Except for testing how long the air-conditioner would run, I have never brought the batteries down lower than about 85%, meaning Iíve only used 15% of their holding capacity in normal every day use which runs a power-hungry refrigerator and whatever it is that Iím charging up when Iím not driving. Driving during the day of course, helps keep those batteries topped up.
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Old 08-16-2018, 07:11 AM   #10
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Advanced RV sent me a spec sheet on the Quiet AC. It said that it was rated at 14a@120v. That is too much for me.

I was reading about the Colman Mach 3 PS, 13500 BTUs, 11.2a@120v. The only problem is that it's 13 inches tall.
I liked the Power Saver efficiency, but my Airstream Avenue requires a low-profile of less than 10 inches. So had to go with a another unit.

I installed a new Coleman Mach 8 Plus on Monday. The seller's ad was wrong and I received the 15K btu instead of a 13.5K. Based on advice from members on airforums.com, I decided to keep it since it is only larger by 11% and most said I wouldn't regret it. PPL motorhomes is refunding the freight shipping costs of $140 due to their mistake.

I posted a review here Is there such a thing as too much A/C? - Page 3 - Airstream Forums but the two main pluses are it has an actual low speed (my old Coleman Polar Mach speeds were high & higher) which is noticeably quieter and, best of all, draws only 12-13 amps which is a couple less than the old smaller 13.5K. I guess efficiency improvements were made in the seven years since out old unit was made.
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