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COArgosy78 · 02-25-2003, 10:44 AM

I found this little tidbit and thought it might come in handy to others reading here on ASForums. Leigh

RV TECH TIP. By Mark Polk

Q: We plan to do several days of dry camping at a time. Is there a
way to calculate how much propane we will use?

A: There is a way to roughly calculate propane usage. You need to
know how much propane is in your RV when it is full. An RV propane tank is full at 80 percent of its capacity to allow for expansion. Multiply your propane container capacity using one of these formulas, (gallons or pounds), to determine container BTU capacity. BTUs per gallon equal 91,502.BTUs per pound equal 21,548. Divide your container BTU capacity by the total BTU demand of the appliances you are using. BTU appliance demand
can normally be found on the appliance or in the appliance owner's manual.
This will give you an idea of how long you can expect your LP gas to last.
For example, if your RV propane container holds 14 gallons of LP gas when it's full, you multiply 14 X 91,502. The result is 128,1028. You divide this figure by the total BTU demand of appliances, let's say 43,800 BTUs, which gives you approximately 29 hours of use.

Mark Polk is the producer of the video series RV Education 101.

RoadKingMoe · 02-25-2003, 11:21 AM

Go here and click on 6lb - 40lb Specifications.

You can figure out how many gallons of water the tank holds from it's water weight capacity (stamped on the tank), and multiply that by a percentage to find usable gallons, and multiply that by 91.500 btu/gal or...

you can just look at how many gallons of LP Worthington says the tank holds and multiply that by 91,500 btu/gal.

or more simply, if you have a 40 lb tank, it holds 40 lbs of propane and multiply that by 21,560 btu/lb for 862,400 btu.

Usage is a little harder. If you have a 34,000 btu input furnace and it's running 1/3 of the time, on average throughout a 24 hour period, it's consuming 11,333 btu/hr or 272,000 btu/day.

The refrigerator is similar. You have to figure out how many btu/hour it consumes if running 100% then figure out what percentage of the time it's running.

Same with the water heater left on constantly. If you only run it long enough to heat one tank of water, then it takes 1 btu to raise the temperature of 1 lb of water 1 degree F. A 6 gallon tank is about 50 lbs, so to raise it 80 degrees (from 60 to 140) or 4000 btu. How much energy it consumes to keep it there is a different story.

john hd · 02-25-2003, 04:47 PM

on my last cold weather run i found a 30lb cyl. lasts about 3 days.

68 degrees inside, low teens at night and mid 30's during the day.

john

Silvertwinkie · 02-25-2003, 07:47 PM

John,

That's not long at all! I thought I'd get about a weeks worth out of a 30# tank running the heat at about 70*. OUCH! Given the fuel costs around here, it's gonna be an expensive winter in dry dock.

Eric

thenewkid64 · 02-25-2003, 07:51 PM

John,

Your usage matches what I experienced while waiting to go to FLA for a trip with our 31 FT TT. We kept it heated from Oct to Dec 15th in Milwaukee with temps as low as 5 degrees at night.

3 days per 30# tank was our average.

Pick · 02-25-2003, 08:59 PM

I called my propane supplier that fills our 100 gallon house tank, and asked how much to fill my 30# tanks. I nearly fell off my chair when she told me $23.50 each!!! To the Flying J I go!! Even if I spend $5 worth of gas to get there and back, I save a ton of money filling 3 tanks.