MPG w/Gen set & Coach AC or Dash AC

[Field Trip]

Somewhere a while back, I read a post where they claimed that their MPG was the same if you shut off the Dash AC, and used your Gen Set to power the coaches AC units.

Fact or Fiction?

[njs42]

There was a recent thread on this subject---this past week, Search and you should find the responses. Basically no definative answers as I recall----but it seems to me it depends on you and your rig. Try it and see what happens---run with dash air check the milage---then with roof air and do the same-------then you know about your rig someone else may have a different experience---for many different reasons.

[footdoc]

I did some recent calculations for my coach and think I ended spending a tiny percent MORE to run the dash air vs house air, but the comfort level is greater with the dash air on...I think I will use dash air in the sun and house air after sunset....

[clubmed98]

The q is ...does a compressor cause a loss of engine power equal to a gen set at X gallons per hour on load...probably smaller engine size then gen set might be better big engine probably not..think I remember this discussion from many years ago and dash air beat gen set hands down...

[Mr_D]

Quote:

Originally Posted by njs42 There was a recent thread on this subject---this past week, Search and you should find the responses. Basically no definative answers as I recall----but it seems to me it depends on you and your rig. Try it and see what happens---run with dash air check the milage---then with roof air and do the same-------then you know about your rig someone else may have a different experience---for many different reasons.

And after 50,000 miles each way let us know what you find!! One or two tanks is not enough to tell. Cummins has a white paper detailing their findings but they say it takes 144,000 miles to get an accurate overall reading

[soricobob]

It's difficult to compare the two. The dash a/c cools the front only, and the engine runs a bit hotter with it on. The gen a/c cools the whole house, and I find uses fuel at about 1/2 gallon per hour.

[Perry White]

I run them both. I want comfort, not economy.

[chofujohn]

I got 9.5 mpg on a 1,200 mile trip after taking delivery in St. Augustine. I've got the ISC 350 engine. I drove the whole way at 60 mph on cruise control. In 1,200 miles I used 126.3 gallons. At 60 mph it took 20 hours to get home. If you pull a heavy load (2 a/c's) on the genset Onan says the the generator will burn 1.2 gallons per hour. Light load is .5 gph and medium load is about 1 gph. So, on my trip I would have used 24 gallons for the genset. When I add that to the consumption calculation that brings the total consumed diesel to 150.3 gallons total. The ammended consumption is then basically 8 mpg.

I don't know what turning off the dash air would add back, but I'd wager it is not close to the 1.5 mpg that was lost running the generator. That's my best guess, anyway.

This is another idea for staying cool while driving. I got this idea from someone at an Interstate rest area. They had a shower curtain installed behind the front seats thus trapping the cold air up front where it is needed most. I thought that was pretty ingenius. I'm going to do the same thing just as soon as I can find the right shower curtain. If the curtain is dark enough then it would also be good as a privacy curtain. I don't know about you guys, but the factory curtain is a pain for me.

JD

[Dave1956]

I have heard about the shower curtain idea, but wonder if it will make cooling the coach off more difficult when I finally reach my destination?