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Old 06-28-2012, 11:30 AM   #1
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use of generater for house AC in travel

I am sure this has been talked about many times but as summer heats up thought I would ask if most use their gens in travel. Most of us know how inefficient our cab air is so why not, right. What about the rear unit as the rear bedroom really heats up with the big diesel adding to the above sun rays beating on roof, do you close off bedroom and keep that thermostat high or leave open and run both ACs ..or suffer with cab air?

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Old 06-28-2012, 11:31 AM   #2
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We use ours. At 40 feet it can really heat up.

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Old 06-28-2012, 11:35 AM   #3
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I think you will find that most people use their generator to power the house AC units while traveling, if conditions warrant. There is absolutely no problem running the genny or the AC units while underway.
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Old 06-28-2012, 12:30 PM   #4
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Originally Posted by buck454 View Post
...do you close off bedroom and keep that thermostat high or leave open and run both ACs ..or suffer with cab air?
I refuse to suffer. LOL

OK...FACT...my 5.5kw Onan's published fuel burn is .9 gph at full load. My AC runs about 1/2 load if both compressors are in use putting my expected fuel burn closer to .5 or .6 gph

Working theory:

I've read that dash air reduces mpg by 1/2 or more mpg. So, if I drive 60 miles (at 60 mph) at 8 mpg I will use 7.5 gal with the dash are on and 8 gal with the gen/coach AC running. That means I will burn an extra .66 gal. That is practically a wash except I am not suffering.

Now, consider this. If you are fighting head winds or hills you now see your MPG go down. Let's assume it is a bad day and you are now muddling along at the same 60 mph but now are burning at 6.5 mpg and 6.0 mpg with dash air. The gals burned respectively are 9.23 & 10.0 and the gen/ac saves about .77 gal in an hour. Now you save a little bit of fuel by using the gen and coach air and don't suffer.

Now, finally, if you hit hills you will not be bleeding any HP off the engine. You should save fuel by the buckets, have more HP available for the climb, and stay cool at the same time. Here is an example. 20 min climb at 45 mph (15 miles) burning 4.5 mpg with dash and 4.0 without dash air. That is 3.33 gal vs 3.75 gals used. Dash used an extra .42 gal while gen used about .2 gal.

Even if the dash air only costs about .25 mpg you are near break even in most flat land, easy driving situations but motoring along with a cool environment. Any headwinds and/or hills quickly closes that small gap. I would also suspect that the tranny will not kick down as often in rolling terrain.

Hey...it's a working theory.

CAVEAT...diesel operators may have different opinions on the affects of dash air. Your mileage may vary, see own's operator manual for more information, my theory comes with no warranty implied or otherwise and always drive safe.
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Old 06-28-2012, 01:22 PM   #5
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i run mine almost all the time while in motion, but having kids in the back that want to watch a movie or something dictates that i have it on. if it's on we may as well have those a/c's blowing.
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Old 06-28-2012, 01:26 PM   #6
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Originally Posted by Ramblin View Post
I think you will find that most people use their generator to power the house AC units while traveling, if conditions warrant. There is absolutely no problem running the genny or the AC units while underway.

Although, this is an area where we must be pretty lucky because our dash air seems to do a very good job unless we find ourselves in extreme conditions.

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Old 06-28-2012, 01:34 PM   #7
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ALways running the genny when underway. We stay at campgrounds so it wouldn't get used if we didn't and that's bad for the genny. It's powering our 2 acs and the frig. and yes we are comfortable!!!!!


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