Generator or Engine A/C?

fletch460 · 01-24-2011, 03:26 PM

I read somewhere it is better economy to run the genset down the road then to use the engine a/c. Manual says genset burns .6 gal. with a/c running. That computes to about four miles of driving. Would engine be pulled down more? I understand less load is more power for running. If this can't be answered here it cant be. Any thoughts here?

94-Newmar · 01-24-2011, 06:21 PM

You don't mention gas or diesel, might want to put your rig's details in your signature line for future posts

That being said, I take issue with the .6 gal/hr on the fuel consumption IF you're talking diesel gensets. Not just on your post, but others I've on this and other forums.

Im a fanatic on figuring fuel mileage. I never let it go under 1/2 tank at any time (500 miles), and i know from that point it takes 50 gals to fill it back up. My tank holds 100 gal and I know i get between 9.4 and 10mpg depending upon grade, speed and wind. We once camped a whole weekend on generator only. The grounds we camped on were 2 miles off the interstate and i filled up at the exit. We ran the generator the entire weekend, never shut off from Friday afternoon until Sunday afternoon - both AC's (85 degree days), most all the lights, 2 LCD TVs, DirecTV and normal microwave oven usage. Before we hit the upon leaving I topped off again - it only took 15 gallons. In my book thats only .3 gal/hr. Before I started paying attention I always thought my Cummins/Onan 7.5K did really really well on fuel consumption. Mine is obviously an older type, not the newer inverter type... perhaps the older ones do better on fuel consumption.

1ciderdog · 01-24-2011, 06:30 PM

To me it is a comfort factor not a cost factor. If the dash air will not cool the coach I use the generator and A/C. If it is hot outside I do prefer to get to a campground with a cool interior. Sometimes it seems to take forever to cool the RV with the "house" air conditioner when arriving hot in a campground. (If mama's not happy no ones happy)

fletch460 · 01-24-2011, 09:53 PM

Sorry I didnt mention rig. It is gas and engine is 460 ford. I got the .6 gal out of the onan book. It is in old,94 model, class c-. The genny is only a 4000 watt. I feel like I am running around in a toy compared to some of your rigs. Not mad just envious. Maybe I should rethink about comfort vs. economy. I will put specs in signature as soon as I learn how. I appreciate the input and take it to heart.

JimM68 · 01-25-2011, 05:54 AM

The dash air in our Pace Arrow f53 easily cools the entire coach in any weather.

denochs · 01-25-2011, 06:44 AM

There is an obvious difference when comparing a 4K gas & diesel gen set. Diesel is more efficient. However, it comes down to size and load. Our 10K diesel genny uses close to 1 gph when running all 3 A/C units and less when running one.

I found this to be the same on my 5K gas genny at home. When put under load you can hear the engine labor if the load is heavy enough.

In my opinion it comes down to comfort. Our dash A/C doesn't do much for us in 85+ degree weather.

Dave

powderman · 01-25-2011, 06:50 AM

At idle before there is any load on the engine, the 5.9 Cummins burns about 1 gal per hour. Much more sense if parked to run the gen set. If going down the road, who knows??

bldrbob · 01-25-2011, 06:59 AM

My dash air hasn't worked in five years so I usually use the genny.

GaryKD · 01-25-2011, 07:14 AM

I'm with 1ciderdog. For me the cost factor is not even in the decision process. What ever works for the passengers (wife, Gkids and a set or two of parents) is how the decision is made.

When the coach HVAC is active, I may also be running the automotive HVAC. As the driver, in front of the large slide wall, I need to be comfortable too.

B Bob · 01-27-2011, 09:21 PM

If the dash air does the job that is what I would use. If it gets too hot inside with only dash air then turn on the genny and roof air. The you can turn off the dash air. From what I have been told dash air on a gas motor like yours pulls 4-6 hp. My guess would be that running dash air is cheaper than genny running.

HMXDave · 01-28-2011, 12:08 PM

Top Gear did a episode where one guy was running with no AC and the other ran with it on...the mileage difference was not appreciable. Granted, these are sports cars...but I'd say running the dash AC doesn't affect the mileage much on a unit with a huge motor pulling heavy loads anyways.

94-Newmar · 01-28-2011, 12:16 PM

I didnt see that on Top Gear but instead on Mythbusters. They didn't test with the AC on versus Off per se, they instead tested AC on with windows rolled up versus AC off with windows rolled down. Their findings showed that a vehicle with the windows down suffered an appreciable decrease in fuel mileage due to the increased wind resistance and drag of the wind cavitating inside the passenger compartment.

Tha_Rooster · 01-28-2011, 12:29 PM

If the suns shining bright and hot I'll run both to keep me and family cool so if you burn as much as 1gal an hour it's worth it for me.

akadeadeye · 01-28-2011, 12:44 PM

Quote:

Originally Posted by fletch460

Sorry I didnt mention rig. It is gas and engine is 460 ford. I got the .6 gal out of the onan book. It is in old,94 model, class c-. The genny is only a 4000 watt. I feel like I am running around in a toy compared to some of your rigs. Not mad just envious. Maybe I should rethink about comfort vs. economy. I will put specs in signature as soon as I learn how. I appreciate the input and take it to heart.

Fletch,

Go to User CP (upper left screen), then find Edit Signature in the left column, then fill in the blank and click Save Signature

Don