Is your RV furnace burning your money?


By Russ and Tiña De Maris

Here’s a question worthy of posting on an Internet RV forum: “How much propane will a 15,000 btu RV furnace use in a day?” The question got posted – and it was certainly legitimate enough, but not a soul offered to render an opinion. Perhaps the safest might be: “Too much!”

“How much money will you spend to heat an RV?” is a frequently heard question when the cold weather rolls around and people think about getting away from the house and back to the great outdoors. Sad to say, the question is on a par with, “How much wood could a woodchuck chuck?” There are so many variables: How big is the RV? How well insulated? How cold is it outside? How warm do you want to keep the inside? What size is the furnace — or are you even heating with a furnace?

Here’s a scenario: A couple in Quartzsite, Arizona, were bemoaning how cold a winter trip had been. They have a 40-foot trailer, and based on an eight-day propane consumption history, they came to a nasty conclusion: Using their trailer’s furnace, it would cost them nearly $170 a month to heat if things stayed the way they were over the “trial period.” Needless to say, adjustments had to be made.

How much propane can you use? For them, their furnace is rated at 40,000 btu input, and a 31,000 output. A little math and a little propane background will help. A gallon of propane will supply 91,500 btu. Run their furnace a little over two hours and 15 minutes, and a full gallon of LP is burnt. Put another way, at $2.32 a gallon, for every hour of operation, $1.02 is spent. To add to the insult, 23 cents of that $1.02 is simply “thrown out the window” due to heater inefficiency — if you lived in a perfect world. But by the time you account for heat loss from ducting the heat throughout the rig, the dollars thrown away in this system are almost too painful to contemplate.

The couple finally resorted to closing off the areas of the rig when not in use, keeping the thermostat set at a chilly 50 degrees at night, and running an electric space heater in the areas being used, keeping the fuel hog furnace for use in heating the place up in the morning.

It’s no wonder that many RVers have opted out of using their rig’s factory furnace. Often they use alternative propane heaters: Blue flame, catalytic, or “brick” heaters. Nearly all models of these units are “unvented” meaning they are not connected to the outside. Almost 100 percent of the energy they consume in the form of propane is turned into heat. Keep in mind, to be safe you’ll need to keep a window or vent cracked to bring in oxygen, which translates to a heat loss itself. However, the efficiencies are higher and the equivalent amount of LP used is much less than a built in furnace.

There are other considerations: Putting 100 percent of the heat into the RV also means 100 percent of any combustion byproducts. There’s a whole world of controversy among RVers about just how safe or unsafe unvented heaters are. To that end, if you decide to use an unvented heater, ALWAYS follow the manufacturer’s instructions to the letter. We shop for heaters with oxygen sensors — these will shut down the heater in the event the amount of oxygen in the RV gets so low as to present a health threat. We also insist on having a working, frequently tested, carbon monoxide alarm in the RV.

How much LP will you burn with an alternative heater? When it comes time to refill your LP cylinders, no doubt you’ll moan, “Too much!” but it’ll certainly be less than with your monster furnace.

##RVT774 ##RVDT1272

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I’ve often wondered why some manufacturer hasn’t come up with a more efficient furnace. The exhaust on the furnaces will burn you. My home furnace used pvc pipe for an exhaust that gets about 104 degrees. Yes, you’d pay more but in the long run save money 💰 if they were more efficient. I think regular ones run around 70 to 80 percent efficient vs high efficiency of 95+.


We seldom need to use the furnaces except for a quick warm up in the morning. Don’t heat at night, use an electric blanket and during the day have two Honeywell tower heaters. If below 32 degrees at night will run furnace long enough to heat water bays. If over 40 outside can use the heat pumps. But we don’t pay electric at our campsite so it not only is less expensive it means we don’t have to move the motorhome just to refill propane.

Donald N Wright

My Aliner doesn’t have a heater. It has a 10K BTU Cool Cat A/C, but no built in propane heat. So where electrical power is available, I have a little Walmart $20.00 electric heater, and in National parks, a little Buddy heater. Aliners have lots of air leaks, so venting usually isn’t a problem. Also a small battery operated fan helps move the air around. In summer months, I open the windows !

Jim Collins

Best electric heaters are the ones that look like a baseboard hot water heater we have one and it keeps our 30′ jayco warm , they are filled with silicone oil, and very efficient


We are lucky enough to have a semi permanent place to park our RV. We lease a 250 gal propane tanks for 60.00 yr. we have a wet line on it and fill our own bottles. 1.85 per gallon (125 gal minimum) is much cheaper than 4.00 at most local fillers. Also we run direct using quick connects when parked. I don’t recommend using any type of internal propane heater because in cooler weather it causes excessive moisture to form inside our 40 ft fifth wheel. The eventual moisture damage would exceed the extra few cents saved. Electricity here is about 12 cents per kwh. If propane is more than about 2.80 per gallon, then electric is cheaper. Unfortunately even with a 50 amp service we can only run 2 space heaters when combined with other accessories, so we have to supplement with propane. If you are doing an ‘extended stay’, there are several propane companies that will rent you a larger tank. The 120 gallon tank can be placed within a couple feet of your camper, anything larger must be at least 10 feet away. The 400lb (120gal) tank can be purchased outright for about 500.00 ( Then you can use any company you want to fill it. Would only be feasible if had a place to leave it.

Robert Wilkinson

I have to comment on this. Where did you get your cost for propane, I have never paid $2.32 a gallon. I pay $15.00 per bottle at most. (30 lb) Also letting you trailer sit at 50 deg. overnight in an area where it can go below freezing, will cause your piping to freeze. Also some trailers do not have heating pads on the tanks. The tanks are heated by the furnace , so you have to run it to prevent damage to your tanks. If your going to do an article on this, include some of the different variables so people will get a proper perspective on it


Thank you for this indepth look at the terrible RV propane heating furnaces. We use electric heat with an IR lamp and a small space heater. LP is nothing to mess with, I have gotten LP poisoning and it is a rotten feeling of sea sick and vertigo! Of course, it is still better than not smelling it and not waking up. Our power bill fluctuates from $125.00 to $160.00 in any weather(100F to 25F). The $35.00 difference is not worth risking my life for at all. If the camper uses 50#’s or about 12 gallons(approx.) every month, at $3.50 per gallon it would cost $42.00 per month. It’s a beneficial and safer to use electric. Please, this is not a cause to die for…

Tommy Molnar

I tried to use a “Heater Buddy” in my 10×12 shop years ago. I found myself getting dizzy long before the auto shutoff on the heater did its thing. I had a window cracked too. So, I’m a bit concerned about these heaters in our trailer. I know bazillions of RV’ers use them, but I’ve had a bad experience with one, and that’s that.