Most RVs have furnace systems that run off of propane gas - but how much do you really need for keeping your rig warm?
When our family started living fulltime in our RV, we had to figure out how to keep warm, but also keep track of how much propane we were using. This article will explain how much propane an RV furnace uses, and describe how to stay warm and conserve propane.
The amount of propane used by a furnace depends on the size of the furnace. The larger the furnace, the more propane it will use.
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A gallon of propane has an approximate burn rate of 90,000-100,000 BTUs per hour. The average-sized RV furnace will burn about 1/3 of a gallon of propane while running continuously for an hour. Based on this estimate, a gallon of propane = 3 hours of continuous RV furnace use.
How does this information practically affect your furnace use? Are there any factors that can slow down your propane burn rate? Read on, and I'll explain how you can approximate your propane usage, and save costs by using your RV furnace efficiently.
How to calculate the rate of propane used
To calculate how much your propane your furnace will use, you need to look at the BTU rating on your specific furnace. BTU stands for British Thermal Units, which is the standard unit used to measure how much energy a heating system can produce.
The higher the furnace's BTU, the more heat can be produced by your system, and the more propane it will use.
One rule of thumb for calculating BTUs needed to heat an RV is to estimate 1,000 BTUs per linear foot of the rig. So, a 30,000 BTU furnace can adequately heat a 30-foot trailer.
The RV's Furnace size
RV furnaces come in various sizes, measured by their BTU. Let's take a look at common furnace sizes.
30,000 BTU furnace
A 30,000 BTU RV furnace will use 1/3 of a gallon of propane in an hour of continuous use. Therefore, it will take 3 hours to use a gallon of propane.
Of course, how quickly you use your propane also depends on the size of your propane tanks. This varies from rig to rig, so you'll have to calculate according to your own capacity.
In our rig, we have two 20 pound propane tanks. With a 30,000 BTU furnace, using our RV furnace for 60 hours will empty one of our propane tanks.
If we use our RV furnace for 12 hours a day, one propane tank will be gone in 5 days. If we use our furnace for 6 hours a day, the tank will be empty in 10 days.
20,000 BTU furnace
A smaller furnace will burn through propane less quickly. Using the above equation, this furnace will use approximately 1/4 of a gallon of propane in an hour of continuous use. So, it will be closer to 4 hours of furnace use to drain a gallon of propane with a 20,000 BTU unit.
40,000 BTU furnace
With a larger unit, propane will be used more quickly. At the propane burn rate of 90,000-100,000 BTU's an hour, it will take two and a half hours to use a gallon of propane.
What if you have more than one furnace unit?
Larger rigs (above 35 feet) may have two furnace units installed to warm up a greater area. While that might seem to increase the propane burn rate, it's not likely that both furnace units will be running at the same time. Since they cover different living areas, only one will probably be in use at a time.
Obviously, the less one uses their RV furnace, the more propane they will save. However, making sure an RV furnace is running efficiently is another important way to conserve propane and cut costs.
Tips for increasing RV furnace efficiency (And saving on Propane!)
There are things you can - and should! - do to save on propane.
1. Improve the insulation in your RV
As we all know, RVs are not as well insulated as other types of homes. Once our RV furnace reaches the desired temperature, it doesn't take long for the cold to creep back in. This, of course, forces the furnace right back on. What steps can RV owners can take to keep warm air in longer?
Plug up any leaks
The most common places for air to leak into an RV are around the windows, slides and doors. Check the seals around these and make repairs as needed. Painters tape or Thermoguard tape can be used in a pinch to repair a bad window seal or other gaps.
If you feel cold air coming into your RV, see if you can locate where it's coming from on the exterior. Often this can be easily plugged with spray foam or silicone rubber.
Some RVers use "snakes," to cover the space at the bottom of their door and keep cold air out. These are like cloth-covered tubes that can be purchased at Walmart, or created on your own with a little sewing know-how.
Use window covers and shades
Windows are notorious for causing cold drafts inside an RV. You can purchase pre-made window coverings with insulating or reflecting materials to reduce draft.
To save ourselves money, we bought a roll of Reflectix insulation and cut it ourselves to fit inside our windows. With these window coverings over our windows, the cool air stays out more. This helps our rooms stay warmer and improves our furnace efficiency.
2. Regularly maintain your RV furnace
- Make sure your returns and vents are clean and free of dust
- Keep your safety detectors up-to-date
- Avoid blocking airflow
- Check outside vent for soot
- Have your system serviced regularly by a certified technician
3. Set your RV furnace to a low temperature at night
This may be obvious to many of us, but during the night, you should not be continuously running your RV furnace. If you set it to a low 52-54 degrees, it should only turn on occasionally during the night. Make sure you layer up when going to bed and choose warm bed covers. Consider investing in an electric blanket for your RV bedding, to make sure you stay toasty warm.
4. Consider using a ceiling fan
Not only do ceiling fans cool rooms down in the summer, but they can keep warm air circulating too. Just like in a house, if the fan is turned to reverse mode, it can push hot air from the ceiling back down into a room.
Check out our guide about 12V ceiling fans for RV's.
5. Planning on long stays in cold areas? Consider a four-season RV.
Four-season RV's are designed to withstand the cold. They come fully insulated inside and out, with protection for your tanks and pipes as well. The additional insulation means they keep warm for longer while saving on propane.
Read more: What makes an RV truly four-season?
Can my RV furnace run on battery power?
Great question! If we are trying to save on propane costs, it makes sense to look at other energy sources to heat up our RV. Electrical power is an obvious choice.
Unfortunately, RV furnaces cannot run on electricity alone. A large enough battery can certainly power your RV furnace to ignite and blow where it needs to, but it won't create the heat. You need to have propane for the heating mechanism.
So yes, if you are boondocking with a generator and battery, and your propane is abundant, then you definitely can run your RV furnace without hookups.
However, if you are trying to save propane, you're going to have to look for another system to provide heat to your RV besides your furnace.
Other ways for heating your RV
You don't have to use your RV furnace to generate heat. At least not exclusively. Here are some alternatives to consider.
Electric space heaters
We highly recommend buying an electrical space heater for your RV. Something you can easily move into the living area of your RV during the day, and into the bedroom at night.
If you are shopping for an electric space heater for your rig, here are a few points to keep in mind:
- Ceramic space heaters are more durable and have a safer heating mechanism than other heater types.
- Think compact design with a small footprint. Who really needs more things cluttering up their RV?
- Choose a lightweight unit with adjustable speeds
- Look for a heater that has built-in sensors which will automatically shut off in case it is bumped or knocked over
- Oscillating features and a remote are nice to have, but not essential
Electric space heaters can greatly reduce the amount of time you need to run your RV furnace. In our case, we use our electric space heater as our first choice, and only run the furnace when it's much colder.
Another bonus of electric heaters is that they do not create the same amount of condensation as a propane-powered heater does.
If you are in a boondocking situation, without any electricity, then the electric space heater won't help too much. But, if you are in an RV site with electric hookups, then running the electric space heater will be more cost-efficient than running your furnace.
What about my RV fireplace?
More and more RVs are built with electric fireplaces pre-installed. While many of us prefer the natural glow of an outdoor campfire, these electric fireplaces do provide extra heat inside.
Electric fireplaces can be used exactly like a space heater described above. The only downside of these is that they are not portable. But they can help you save on using your furnace.
A few more propane handling tips
These could help save on propane as well.
When facing cold weather in your RV, make sure your propane tanks are full. Calculate approximately how many hours you can run your RV furnace before running out of propane. Then be sure to stay under that amount of time.
Use low settings on your furnace at night, and remember to insulate your RV as well as you can. Run an electric space heater or RV fireplace during the day to supplement your furnace use. With these precautions and tips, you should be able to make your propane last and stay warm while RVing in cold temperatures.
Over to you. If you're a fellow RV'er and have dealt with this question too, let us know if you have any tips to add!
Thursday 20th of January 2022
I would like to know what efficiency Rv LP gas furnaces are? Are they 90%, 80%, 70%,60%,50%??
Sunday 31st of May 2020
Great information for a new rver like me.
Monday 16th of December 2019
You made a large error confusing pounds of propane with gallons. They are not the same. One gallon weighs 4.25 pounds, so your two 20 pound propane tanks have less than 5 gallons in each of them. So running your furnace for 15 hours will empty one of your tanks. Not 60 gallon as you mistakenly reported.
Thursday 23rd of January 2020
Thank you for your comment, Dan. Unfortunately, the writer of this piece - an experienced RV'er herself - is not available to check and fix this. I do appreciate your comment and hope others will take note.