Driving with the generator on

Well you can also use the 12v for the fridge dry camping so I don't necessarily think the 12v is there for just going down the road . That said mines on going down the road all the time. I shut it down to get gas though.

JaxDad wrote:
I don't know about the insurance part of it, but in several Canadian Provinces it's illegal to go down the road with open propane cylinders unless it is the fuel source for the vehicles engine.

I suspect if it's illegal then the insurance company would deny coverage purely on that basis even if you're not from there.

I think that may apply to propane bottles but not frame mounted tanks.

Q: Do any trailers NOT have 3 way fridges where you would use 12VDC to run the fridge in transit? (meaning, they should have their portable bottles OFF)

tatest wrote:
Don't even think of it as difference in MPG, rather as 0.5 GPH (A/C is roughly 1/2 load) or about $2 per hour to have the house cool.

I guess it depends on what m/h you have, the dash a/c in my E-350 chassis will keep the entire coach pleasantly cool at highway speeds regardless of the outside temps I drive through.

I can't even measure the loss in mileage.

Don't even think of it as difference in MPG, rather as 0.5 GPH (A/C is roughly 1/2 load) or about $2 per hour to have the house cool.

Impact on MPG depends too much on all the other things that impact MPG, e.g. wind drag and travel speed. Running A/C drops MPG a lot more at 30 mph than it does at 70 mph, and sitting in a parking lot you are getting 0 miles per gallon while still burning 1/2 gallon per hour.

I don't know about the insurance part of it, but in several Canadian Provinces it's illegal to go down the road with open propane cylinders unless it is the fuel source for the vehicles engine.

I suspect if it's illegal then the insurance company would deny coverage purely on that basis even if you're not from there.

Fastpaddler wrote:
I dont know about the US or even specific Canadian provinces but my understanding is that if you have the propane turned on in your rv while driving on the road(presumably it is being used for fridge or aircon), you may invalidate your INSURANCE if you have an accident. I used to keep my propane on for the fridge but now I use the house battery while on the road. Just saying...

AL

Can you provide any documentary support for your assertion? A significant portion of RVs only have AC/LP fridges. The are designed to operate on LP while being driven.

maillemaker wrote:


I think a big part of our problem is even with the cab vent/air shut off outside air still comes in from somewhere down by your feet.

Steve

We haven't noticed any outside air coming in on either side of our's.

Our Itasca is fine up front with the roof air running. Our Coachmen was fine when it had a 13,500 Btu Dometic followed by a 13,500 Btu Carrier, but it's not fine with its' current 15,000 Btu Advent AC. It must be due to the positioning of the forward vent on the Advent. The Itasca has ducted AC, while the Coachmen doesn't. My previous Class C was also fine with its' nonducted roof AC.

I think a big part of our problem is even with the cab vent/air shut off outside air still comes in from somewhere down by your feet.

One year we went to Disney and our heater core blew as we pulled in. The mobile tech ran a bypass so we could get home, but we had no cab heat. It was unbearably cold in the cab as there was a freezing flow of air on your legs. We tried putting a blanket on our legs but eventually we stopped and bought a little space heater to put by our legs and ran it off the generator.

Steve

darsben wrote:

JaxDad wrote:

darsben wrote:
All in all I feel the economic part is close to a wash but the convenience and comfort level is much greater.

A typical dash air system takes maybe (on average overall) 2hp, on an engine making 200hp, that is a 1% increase in load, therefore an increase in fuel consumption of 1%.

At 8.5mpg and 55mph that equates to 6.47 gal. / hour. A generator burning 0.5 gal. / hour would then be an increase of 7.7% in fuel consumption.

That's the equivalent of your mileage dropping from 8.5mpg to 7.9mpg.

I'd hardly call that "a wash".

Now factor in the savings from not using propane to cool fridge and it makes it CLOSE to a wash

Just how big is your fridge???????

Again, rather than 'gut feelings' lets actually look the FACTS.

There's roughly 91,500 btu's in a gallon of propane. Today that costs about $3.00 / gallon.

A typical 12 cubic foot Norcold RV fridge burns 2,400 BTU / hour.

So one gallon of propane will last about 38 hours of actively cooling time.

If you completely discount ANY rest time (not actively cooling) and not the 1/3rds running, 2/3rds resting time average that means the fridge would cost $3.00 divided by 38 hours or roughly 7.89 cents per hour.

A generator burning 0.5 gallons of $4.00 an hour gasoline would cost $2.00 / hour.

You really think $2.00 versus $0.0789 per hour is "CLOSE to a wash"?

That's more than 25 times the cost per hour. Hardly what I'd call "a wash".

4K-Ranch wrote:
Might run both.

We have only had to do that once - never while going down the road - while parked with the V10 idling and the Onan running during August when it was hotter than blazes in the Texas panhandle. The DW turned all red when boondock rockhunting in the middle of the day -> got her back into our motorhome and fired up both the dash and roof air conditioning systems to cool the whole rig down in a hurry.

The later model Ford dash air con systems in their V10 chassis are superb. Ours cools the entire coach area (only a 24 foot Class C) in fine order, but our worst situation has only been while driving in the low-humidity 90's in Death Valley in March and around a high humidity 100 in the Deep South during August. With both A/C systems running we could probably handle any hot temps in North America, if not the Earth, in our relatively small interior volume rig.

FWIW, we have run both the propane furnace and roof air at the same time once or twice in very rare situations in the Deep South in August: Extreme humidity during only moderate (low 80's) warm temperatures. We needed the roof air full blast to remove humidity and the furnace full blast to keep from freezing. We wound up with 70 degree dry air in the interior -> kindof an emergency situation dehumidifier. You gotta love these modern self contained RVs that can handle a large variety of expected and unexpected fun situations!