Your RV furnace is a pretty important feature of your home-on-wheels, especially if you travel in areas where the temperature can drop below what’s comfortable. An RV furnace will warm your rig up fast, but for how long? Well, that’ll depend on a couple of things… including how much propane you’ve got onboard. That’s why it’s a good thing to know the answer to the question, “How much propane does an RV furnace use?”.
So, let’s take a look at how an RV furnace works, and how much propane it uses on average.
- 1) Do Most RV Furnaces Run Off of Propane or Electricity?
- 2) How Does a Propane Furnace in an RV Work?
- 3) How Much Propane Does the Average RV Furnace Burn Per Hour?
- 4) How Can I Calculate How Much Propane My RV Furnace Is Using?
- 5) What Happens To Your RV’s Furnace When You Run Out of Propane?
- 6) How Can I Reduce the Amount of Propane My RV Furnace Uses?
- 7) How Can I Heat My RV Without Propane?
- 8) How Do I Refill My RV’s Propane Tank?
- 9) Can I Connect My RV to an External Propane Tank?
- 10) Have You Found Your RV’s Propane Furnace Effective and Efficient?
Do Most RV Furnaces Run Off of Propane or Electricity?
Most RVs are manufactured with an onboard propane furnace, unless the buyer has opted for an alternative heat source. For example, an RV might have a hydronic heating system like Aqua-Hot’s diesel hydronic heating system with multiple zones.
It’s also uncommon (but possible) to find an RV furnace with an electric heating element that allows the user to switch between propane and electric heat (like the CheapHeat aftermarket add-on).
But by far the most common type of RV furnace on the road is the propane furnace which uses both propane AND electricity (12V DC from your onboard batteries). Propane heats the rig, but the furnace requires 12V power to run the circuitry, thermostat, and blower fan(s).
Let’s take a look…
How Does a Propane Furnace in an RV Work?
Recently we looked at the question “How does an RV propane furnace work?”. In that post, we went into great detail reviewing what happens in an RV propane furnace between the moment you turn up the rig’s thermostat to when the heat begins flowing through the ducts.
We also looked separately at each of the parts involved in the process. You can check out that post for those details, but essentially what happens is this:
- The thermostat sends an electrical signal to the furnace’s circuit board/control board.
- The electrical signal moves through a relay which starts the blower motor.
- Once the blower fan is at full speed, the sail switch is activated, indicating an airflow that’s sufficient to properly exhaust combustion fumes from the furnace.
- The electrical signal moves to the high-level switch which confirms that the temperature in the burner chamber is safe for the furnace to start.
- The gas valve opens, allowing propane into the combustion chamber while the ignition module on the circuit board sends current to the ignitor in the combustion chamber.
- The current creates a spark between the two ignitor tips, igniting the propane which produces the heat that flows through the heating ducts.
How Much Propane Does the Average RV Furnace Burn Per Hour?
This is a complicated question to answer, partly because there is no “average RV”. There’s great variation from RV to RV in terms of the amount of interior volume that needs to be heated. There are also considerable differences in how well-sealed various RVs are to drafts, how well insulated they are, the size of the furnace, and how high the thermostat is set.
For example, heating the entirety of a 43’ Class A RV like ours requires a whole lot more propane than heating the interior of a Class B rig to the same temperature.
But, our Class A may be better insulated and sealed than the Class B, and we might not turn our thermostat up as high, etc. You get the idea. The wide variations from RV to RV, and from RVer to RVer, make it very difficult to offer an idea of EXACTLY how much propane the “average” RV furnace burns.
But we’ll give you some generalities followed by a way for you to calculate how much propane YOUR RV furnace is likely to use.
Here’s the key: The approximate energy provided by a gallon of propane is 90,000-100,000 BTUs. (BTUs stands for “British Thermal Units”, the standard unit of measurement for how much energy a heating system can produce.)
The average-sized RV furnace is 30,000 BTU/hour. Running continuously for an hour, that furnace is estimated to burn about ⅓ of a gallon of propane. Based on this estimation, the average 30,000 BTU/hour furnace is likely to burn a gallon of propane every three hours.
With a larger furnace, of course, the propane will be used more quickly. If you’ve got a 40,000 BTU/hour furnace, for instance, it’ll take around 2 ½ hours to use a gallon of propane.
While a smaller RV furnace isn’t going to burn through its propane as rapidly as a larger furnace. Given a 20,000 BTU/hour furnace, you’ll burn through about ¼ of a gallon of propane per hour of continuous use. This would allow for around four hours of furnace use per gallon of propane used.
This brings us to your RV furnace…
How Can I Calculate How Much Propane My RV Furnace Is Using?
In order to calculate how much propane your RV furnace is likely to use, you need to first identify the BTU rating of your rig’s furnace. (The higher it is, the more heat your furnace can produce, and the more propane it’ll use.)
Again, the energy content of a gallon of propane is 90,000-100,000 BTUs. Use the BTU rating of your furnace to make the calculations relative to how much propane it’s likely to burn per hour. For example:
30,000 BTU/hour ÷ 90,000 BTU/gallon = ⅓ gallon of propane/hour
Now if, instead, you’re attempting to determine the number of BTUs/hour needed to heat a particular space, keep in mind that the rule of thumb is 1,000 BTUs per linear foot. So, a 40,000 BTU/hour furnace would be sufficient to heat a 40’ rig. A 30,000 BTU/hour furnace would be needed to bring adequate heat to a 30’ RV. And so on.
What Happens To Your RV’s Furnace When You Run Out of Propane?
You don’t want your RV’s tank to run out of propane. Should that happen, the tank’s pressure will drop to the point where the furnace won’t work at all… leaving you in the cold!
A tank that’s left empty for too long can result in leaks when the tank is refilled. And an empty tank can accumulate moisture that causes the interior to rust. When the tank is refilled, the rust can react with the odorant (Mercaptan) in the propane, reducing its odor-causing capability. That could lead to an inability to smell a gas leak in your rig, which is a very dangerous proposition.
So, for many reasons, it’s important not to run out of propane. Be sure to monitor how much propane you have in your propane tank so you’ll know when it’s nearing time to fill up.
If your propane tank doesn’t have a working gauge, see our YouTube video to learn how to check your propane tank level without a gauge:
If your RV furnace fan starts and runs but the furnace doesn’t produce heat, the number one reason for this is an empty propane tank.
However, if you’ve got plenty of propane, you can use our guide to troubleshoot the issue if your RV furnace fan runs but there’s no heat.
How Can I Reduce the Amount of Propane My RV Furnace Uses?
There are actually a few things you can do to reduce the amount of propane your RV furnace uses. Among the most important is regular furnace maintenance.
Tend to the Maintenance of Your RV Furnace
- Check your vents and returns for dust, pet hair, and dirt, and clean them regularly.
- Be sure not to block the return airflow through the furnace intake (inside your RV).
- Check the outside exhaust vent for soot (which signifies incomplete combustion) and/or obstructions (mud dauber, spider, or other insect nests, for example)
- Have your system serviced regularly by a certified technician to ensure it’s operating efficiently
- Be sure to maintain your RV propane regulator (a failing regulator could reduce the flow and/or pressure of the propane supply, reducing the output of your furnace and causing it to run longer)
Seal Air Leaks Around Windows, Slides, and Doors
Windows, slides, and doors are the most common areas where cold air can leak (or blow!) into an RV. Check and maintain the seals around your rig’s windows, slides, and doors, and tend to repairs as soon as you can.
If you find that cold air is entering your RV, in a pinch you could use some painter’s tape to seal the area until you can fix it properly. Or, if you feel cold air entering your rig and can isolate the source as a hole/gap on the outside of the RV, you may be able to use spray foam or something similar to seal up that gap, depending on where it’s located.
For air leaks under doors, you can use various types of weatherstripping, or “snake” tubes that sit at the bottom of the door to keep cold air from seeping in under the door.
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Use Your Shades & Window Covers
Drawing the shades in your RV can help to keep the RV warmer, and if you need additional insulation you could make window covers from Reflectix, cutting the Reflectix to fit. Just be careful not to leave them up all the time as moisture can accumulate on the window.
Keep Your RV Furnace Temperature Low At Night
You can reduce the amount of propane you use in your RV by turning down your rig’s thermostat at night. Using warm flannel sheets and/or a mattress warmer or electric blanket to initially warm the bed before you go to sleep can keep you perfectly comfortable even in weather that’s quite cold.
How Can I Heat My RV Without Propane?
There are a number of ways to heat your RV without propane. Some may not work well in your particular situation, but there are several alternatives:
- Heat pump
- Ceramic space heater(s)
- Catalytic propane heater
- Radiant electrical heat
- Portable propane heater
Be sure to have a look at our video on RV heating options and their pros and cons. We’ve got 20 years of experience to share, and our solutions, honed over that period of time, are reviewed in this video:
How Do I Refill My RV’s Propane Tank?
Refilling your RV’s propane tank may be intimidating at first, but it’s very easy. Why’s it so easy? Because a specially trained person does it for you (at least here in North America they do… in the U.K. you fill it up yourself)!
Perhaps the most important thing for you to remember when refilling your motorhome propane tank is that your rig’s onboard tank needs to be turned OFF, and all propane-burning appliances (furnace, water heater, RV fridge, stove/oven) also need to be turned OFF. This avoids the potential for fire/explosion.
Can I Connect My RV to an External Propane Tank?
Yes, you can! If you’re staying in one location for a period of time, and especially if you expect some cold weather in that location, an external propane tank can be a great and very convenient option. It allows you to function and stay warm in your RV, without depleting your onboard tank(s)… and makes refilling easier, since you can either bring the empty tank to the supplier (for small, portable tanks) or have the supplier come to you (for large, on-site tanks).
We’ve done it ourselves, and we’d be happy to show you how to connect an RV to external propane:
Have You Found Your RV’s Propane Furnace Effective and Efficient?
Tell us about your RV’s furnace. Have you found it to be effective in heating your rig and fairly efficient? Have you encountered any particular issues with your propane furnace? Let us know in the comments below!
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