Community Forums

vagaron · 11-20-2016, 09:16 PM

New to MH ownership. When I picked up our coach in Tucson last month, one of the tech guys at the dealership said some folks run the front A/C off the generator while driving instead of the dash A/C.

He estimated the generator uses about 1/4 gal/hr, so that could translate into higher gas mileage. Anyone concur?

Mr_D · 11-20-2016, 09:19 PM

Sometimes you get better mileage turning off the dash air and running the gen and air cons, plus that allows the engine to work less in the mountains.

adamfolger · 11-20-2016, 09:22 PM

OF course it will impact fuel mileage but not enough to stop us from running the roof air in summer. If you have two airs and your gen is big enough you can run both airs. The dash air will have you sweating profusely.

John Jones · 11-20-2016, 09:23 PM

I rarely use my dash AC. I always run the generator and turn on a roof AC, It works great!

bamaspiveys · 11-20-2016, 09:31 PM

Our Entegra dash air does a good job of keeping us cool in our seats so we don't run the generator. We do turn on the generator and ACs about 30 mins before we reach our destination if the outside temp is warm just so the rest of the coach is cooled down while we setup.

In our Tiffin we had to run the generator and front AC if the outside temp was much over 80, the dash air just could not keep up.

Also in the Tiffin the engine heated up the bedroom something awful. Since we were already running the generator and front AC we would start up the back air to try and cool it off some by the time we got to the campground.

SuperGewl · 11-20-2016, 09:38 PM

I will run all 3 A/C's, the 2 roofs and the engine AC when it is hot enough. You need the front, engine AC just to help cool the windshield. That thing is HUUUUUGE and it loves bring in the sun and heat. It 's really hard to keep it cool so I run all of them when needed. If you are going to worry about the fuel mileage then trade it in and get a 1 ton PU truck and 5th wheel. You can usually get around 10mpg with that type of setup, but you can't have the wifey get you a nice cold water or soda while driving down the road or better yet fix you a sandwich or grab you some cookies and when she needs to use the restroom you don't have to pull over and stop right after you just left the fuel station and she didn't have to go then but does now.
OK I'll stop venting

vagaron · 11-20-2016, 09:53 PM

Sounds as though it's common practice. Just to test the theory on MPG, I did the arithmetic for a simple case. If my calculations are correct, if you're getting 8 MPG @60 MPH w/o running generator or dash air, and the generator uses 1 qt/hr, then running the generator drops MPG to 7.74. That's w/o dash air.

Anybody know how much dash air alone drops MPG? I'm guessing it's more than .26 MPG.

mchero · 11-20-2016, 09:58 PM

Quote:

Originally Posted by vagaron

Sounds as though it's common practice. Just to test the theory on MPG, I did the arithmetic for a simple case. If my calculations are correct, if you're getting 8 MPG @60 MPH w/o running generator or dash air, and the generator uses 1 qt/hr, then running the generator drops MPG to 7.74. That's w/o dash air.

Anybody know how much dash air alone drops MPG? I'm guessing it's more than .26 MPG.

Gas or Diesel generator?

ScottyBye · 11-20-2016, 10:11 PM

I also run the genny and front a/c while driving. Even if it burns a little more fuel (gas in my case) it's worth the comfort.

B Bob · 11-20-2016, 10:16 PM

Read your manual for your generator to get average gal per hour usage. 1/4 gal seems very low to me. Mine is more like 1/2 - 3/4. At least that is what my manual says.

For us we generally always use the OTR air conditioning when driving except when going up really steep long hills when it is very hot. Dash air blows right on me, roof air is back a ways. Our OTR air has a second unit in the rear which helps.

Darwin · 11-20-2016, 10:16 PM

I run whatever it takes to keep us comfortable, especially my wife. Usually dash air until lunch, if temp is above 90 roof air is required also. I didn't buy a motorhome expecting good mileage, although I usually get around 10MPG.

DGBPokes · 11-20-2016, 10:18 PM

You need to double check that reported generator fuel consumption per hour. I had a 5K Onan gasoline in our previous coach, under load used 1.1 gallon per hour. I now have a Power Tech diesel 8K it uses .8 per hour. In the sticks and bricks use to have a Honda 4.5 generator it got .8 per hour.

The Honda had a no load, eco system and it would idle it much get get the number you quoted, with zero load and idle. I've never seen a coach generator with an idle capability.

Redapple · 11-20-2016, 10:35 PM

We run the genny all the time while driving. No worries on that. It does affect overall fuel mileage. At 1/4 load it uses .5 gal per hour, but running both airs your load is probably close to 50%, expect about a gal per hour.

vagaron · 11-20-2016, 10:44 PM

LOL, SuperGewl! Those are the reasons I wanted to get a MH, esp. a class A, in the 1st place. My wife wouldn't want to ride all day in a car, or PU cab, but if she can have the comforts of an apartment on wheels...

I don't worry about the mileage, but the geek in me wants to know the details, even a guesstimate.

I haven't checked the manual. The qt/hr figure was word of mouth. It seemed low to me, too, but since I'd never used a generator before...