Propane Usage in Cold Damp Weather. . .

Wow! What an eye-opener! This has been the coldest year for us in our motor home in terms of furnace usage. We're attempting to limit our electrical use as we “mooch-dock” at our son's newly acquired home here in Georgia. Thus we are almost exclusively using the propane furnace for our heating.

Specs on tank sizes:

Here in Georgia the least expensive source for propane refills I have found is Tractor Supply. Currently they sell propane at $2.79 per gallon. A typical fill to “Full” (80% of rated capacity) in our 5-gallon (20-pound) tank (DOT (Department of Transportation) cylinder) – like you use on gas grills)

is 4.3 gallons depending on ambient temperature and how “empty”our tank really is. That, with 6% sales tax runs us $12.71 – let's just round that to $12.70. At 80% capacity a fill of our 7-gallon (30-pound) tank (I have one of each) is about 5.6 gallons for a rounded total of $16.60.

I did do a fill at a small propane business near Covington, GA that charged $1.15 per POUND which came to $13.90 for a 20-pound cylinder and $27.60 for a 30-pound DOT cylinder. (IF I were filling a large residential propane tank the cost would only be $1.99 per gallon, but that savings is, sadly, not available for the smaller DOT cylinder fills.)

Unfortunately, many folks use the convenience of propane tank exchanges at such places as WalMart, gas stations, etc. These are almost always going to be more expensive than getting a tank filled at a fill station. We did this for quite a while before I figured out how I could be saving some money!

The built-in (welded to the frame of the chassis) propane tank on a motor home is an ASME (American Society of Mechanical Engineers) tank. It also can only be filled to 80% of rated capacity.

Differences between DOT and ASME tanks see this:

To avoid the need to break down our setup when parked somewhere in the motor home, we purchased an “Extend-a-stay” propane kit a couple years ago. This allows us to use the DOT cylinders in conjunction with our ASME frame-mounted tank. We also use these DOT cylinders to power our propane-capable inverter generator

– a topic for another blog! You can purchase these types of kits here:


Be sure to pay attention to the specifics of what is supplied in the various kits offered for sale. Lengths of hoses (IF supplied! See, look at what is in the kit!) allow flexibility of tank locations but may result in stowage concerns for longer hoses when traveling plus the potential loss of all that propane within the hose's capacity when switching over or disconnecting tanks. So longer might NOT be better.

To install these you will need to follow all written instructions and procedures provided by the manufacturer for installation of the kit. You can also watch these (or others):

For us, right now, we're burning through (literally!) a 5-gallon DOT cylinder about every 2 to 3 days(!) – that equates to $130-$140 per month in propane costs for our 35000 BTU SF35 Suburban furnace. We keep our furnace thermostat set at 64 degrees Fahrenheit at night and 72~74 degrees Fahrenheit during the day. Variables in costs are first due to fluctuations of the outside temperature and relative humidity, which governs our comfort needs and thus the demand for the furnace to provide heat. A second variable will be any fluctuations for the price-per-gallon of propane.

Things we could do to reduce furnace heating demands are prevention of heat loss. One way we have done this is to use our sun-block Reflectix pieces made to fit our windshield. This helps to slow heat loss there since the windshield glass is the only single-pane glass in our motor home.

Another thing we have yet to do is install some sort of barrier material in our two ceiling vent areas. These are the industry-standard 14”x14” openings that serve for our Fantastic Fan galley fan and the simpler 12-VDC vent fan in our small toilet room. This will reduce heat loss at our ceiling.

Well, enough for today! Thanks so much for your time and attention. I hope something here helped you in some way.

Cheers! Rotaidalg

Leave a Reply

Your email address will not be published. Required fields are marked *