Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 01-06-2019, 07:14 PM   #1
Senior Member
 
CWSWine's Avatar
 
Ford Super Duty Owner
Join Date: Feb 2017
Location: Manhattan (Little Apple) Kansas
Posts: 2,476
Running AC with Dash or Generator

I have the coach listed below and it has 380 HP Cummins diesel and also has an Onan 8000 watt diesel generator. I read in the owners manual that I would use less fuel running the generator and house air conditioning rather than running the dash air in the coach. Is that true?
__________________
2020 Newmar Baystar 3005 Gas V10 - 2020 Jeep Rubicon
1280 Watts Solar - Victron MultiPlus-II 12/3000/120-50 120V Inverter
300 Amp Lithium Battery
CWSWine is online now   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 01-06-2019, 07:29 PM   #2
Senior Member




 
Join Date: Mar 2016
Posts: 2,960
I've heard that to be true but seen nothing but opinions.

As for us and our coach, the dash air keeps us comfortable. With all that windshield the roof AC's cannot do that.
__________________
Tim
Leesburg, FL '07 American Tradition 40Z Cummins 400 ISL
Towing a '14 Honda CRV
Both sold
2021 Vanleigh Beacon 41LKB 5th wheel
timjet is offline   Reply With Quote
Old 01-06-2019, 07:51 PM   #3
Member
 
Mike Tomas's Avatar
 
Monaco Owners Club
Vintage RV Owners Club
Join Date: Oct 2017
Location: Arizona
Posts: 92
Quote:
Originally Posted by CWSWine View Post
I have the coach listed below and it has 380 HP Cummins diesel and also has an Onan 8000 watt diesel generator. I read in the owners manual that I would use less fuel running the generator and house air conditioning rather than running the dash air in the coach. Is that true?
I wouldn't agree with that. The engine AC wouldn't tak that much horsepower from the engine. But, thats a big rig. That dash AC will not cool the whole cabin in the summer. So most people run the generator for the roof ACs while driving anyway.
Mike Tomas is offline   Reply With Quote
Old 01-06-2019, 08:11 PM   #4
Senior Member
 
Join Date: Jan 2018
Location: UT
Posts: 1,244
Sorry, I don't believe that statement in your owners manual. The AC compressor is only a minor draw on that big diesel engine.
__________________
Ed
2023 Geneva 28VA
Solar and LiFePO4, 2018 Jeep Grand Cherokee Toad
iluvuk is online now   Reply With Quote
Old 01-06-2019, 09:04 PM   #5
Senior Member
 
Country Coach Owners Club
Join Date: Jan 2011
Posts: 1,204
I've talked to a number of Cummins engineers at RMCA rallies over multiple years. It's gospel to them. I choose to believe them. I haven't got the energy, time, or money to investing in trying to disprove them.
pumper9x9 is offline   Reply With Quote
Old 01-06-2019, 09:09 PM   #6
Senior Member
 
CWSWine's Avatar
 
Ford Super Duty Owner
Join Date: Feb 2017
Location: Manhattan (Little Apple) Kansas
Posts: 2,476
Quote:
Originally Posted by iluvuk View Post
Sorry, I don't believe that statement in your owners manual. The AC compressor is only a minor draw on that big diesel engine.
I included a snapshot of my manual that came with my coach. Look at the second question in the FAQ.
Attached Thumbnails
Click image for larger version

Name:	Onan Gen.jpg
Views:	95
Size:	264.7 KB
ID:	231219  
__________________
2020 Newmar Baystar 3005 Gas V10 - 2020 Jeep Rubicon
1280 Watts Solar - Victron MultiPlus-II 12/3000/120-50 120V Inverter
300 Amp Lithium Battery
CWSWine is online now   Reply With Quote
Old 01-06-2019, 09:39 PM   #7
Senior Member
 
avfordguy's Avatar
 
Monaco Owners Club
Ford Super Duty Owner
Join Date: Dec 2008
Location: Kingsville TX
Posts: 1,754
I didn't buy a RV to save fuel
We had a 04 Monaco DP 38 FT in SoCal or Nevada 110 degree heat we ran the 8k onan AND dash air full bore all the time while traveling, since we have sold it because DW hated the hot bed ( over the engine) at nite,would take3 to 4 hrs to cool down, that's one of the reasons we went with a class c.
Ra. All the time with dash ac on full and genset running 2 13.5 ac units figure 1/2 gal/hr for genset still got 7.8 on a gallon with a 330 ISC note the rear fan draws 15 hp at 1800 ac draws 3hp
avfordguy is offline   Reply With Quote
Old 01-06-2019, 11:58 PM   #8
Senior Member
 
Join Date: Jan 2018
Location: UT
Posts: 1,244
Quote:
Originally Posted by CWSWine View Post
I included a snapshot of my manual that came with my coach. Look at the second question in the FAQ.
sorry. Didn't mean to imply I didn't believe you. I believed you were telling the truth. I just don't believe the statement means the dash air burns more fuel than running gen set. after reading your manual, I still dont think that is what it is saying. it is simply saying that the gen is an efficient way to run roof ac and that is what it is for. I would never idle my coach at a camp ground in order to run dash ac. that would be inefficient. the gen would be more efficient than that. to me that is what the manual is saying. however, if already driving, use dash ac. it won't affect engine at all, while your at it, run gen and roof ac too if needed. my interpretation.
__________________
Ed
2023 Geneva 28VA
Solar and LiFePO4, 2018 Jeep Grand Cherokee Toad
iluvuk is online now   Reply With Quote
Old 01-07-2019, 05:48 AM   #9
tcg
Senior Member
 
tcg's Avatar
 
Join Date: Aug 2016
Posts: 1,817
Is this really a concern? Even with my 20+ year old Class C traveling on a budget I just fire up the generator or the dash air or both so my chocolate bars don't melt.

Looking at your rig and toads I can't imagine what you're trying to save.

Just use everything as it was intended to be comfortable.

On my Class C there was no noticeable increase in fuel usage using the generator on a 2,000 mile trip.
tcg is offline   Reply With Quote
Old 01-07-2019, 06:14 AM   #10
Senior Member
 
Old Scout's Avatar
 
Join Date: Nov 2005
Posts: 7,383
...who cares?????, MPG is it not what I bought a 33,000lbs "recreation" vehicle for.....
__________________
Old Scout
2015 IH45 Foretravel
2003 Alpine 40' MDTS [Sold]
New Braunfels, Texas
Old Scout is offline   Reply With Quote
Old 01-07-2019, 06:28 AM   #11
Senior Member
 
Join Date: May 2017
Location: Metamora, MI
Posts: 5,518
I am also a bit skeptical that turning on the A/C compressor while driving will take more adaptive fuel cost than starting and running the generator and roof top air units.

Sure, if you are parked then running the big ole diesel just to run dash air will be fuel inefficient, but their manual specifically says while driving.

But the fuel cost will be what it is. Get comfy and enjoy the ride.
__________________
2002 Newmar Mountain Aire Limited 4370 w/ Spartan K2 and Cummins 500hp
ASE Master Certified (a long.....time ago...)
Dav L is offline   Reply With Quote
Old 01-07-2019, 06:29 AM   #12
Senior Member
 
Join Date: Jun 2017
Posts: 2,807
Quote:
Originally Posted by CWSWine View Post
I included a snapshot of my manual that came with my coach. Look at the second question in the FAQ.
That does not say that you will use less fuel running the generator and AC vs the dash AC.

It says the generator uses less fuel than your engine. Of course it does, but the engine is much larger and used to move the coach down the road as well. Will you get better gas mileage on your engine if you run the generator and AC? Yep, even if you're running the dash AC because the generator and AC is taking some of the heat load.



It should also be noted that your house AC is generally rated at less BTUs than your dash AC.
aether_one is offline   Reply With Quote
Old 01-07-2019, 06:41 AM   #13
Senior Member
 
Join Date: Aug 2017
Posts: 2,091
When traveling there will be little difference in fuel consumption with the dash A/C or the generator running the coach A/C units. A diesel engine will burn .06 gal/hr/hp. So if your engine uses 10 hp for the dash A/C you will burn .6 gallons more per hour. Running the generator will use .6 gallons per hour for the same amount of cooling as your dash A/C. If you are parked , then running the generator will be more economical .
__________________
1993 Tiffin Allegro Bay 32'
Soppy is offline   Reply With Quote
Old 01-07-2019, 07:56 AM   #14
Registered User
 
Join Date: Oct 2016
Posts: 2,078
Maybe that explains the very high hours on generators in some of the Class A's for sale. there are only a few with very high hours and many with very low hours

If the dash air does the job, why have the generator running? Run it as needed for comfort and as noted don't idle the engine for AC, that is definitely generator duty
lwmcguire is offline   Reply With Quote
Reply

Tags
dash, generator



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Want my generator on/off switch to illuminate only when generator is running FloridaCanuk RV Systems & Appliances 17 08-23-2018 04:43 PM
Running down the road with generator running sgrol 5th Wheel Discussion 32 12-26-2015 07:20 PM
What size Inverter For Running 24" TV While Running ? Fourwinds28A MH-General Discussions & Problems 9 09-11-2015 07:35 PM
Running propane heater while running bandmbrown MH-General Discussions & Problems 32 11-17-2014 06:41 PM
Furnace keeps running and running and... marcdohc RV Systems & Appliances 2 10-10-2012 08:58 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 09:44 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.