How Much Propane Does An RV Furnace Use?

Camping in the woods of Maine over Columbus Day weekend isn’t common because of the chilly New England weather. But last year, after purchasing my first teardrop camper, I found myself embarking on as many spontaneous mini-adventures as I could fit into my schedule, regardless of the temperature outside. While most people consider camping a warm-weather activity, those with an RV know they can venture out whenever their hearts desire without having to sacrifice the comforts home. Programmable heating systems are commonplace in most of the RVs and campers on the market today, the majority of which are fueled by propane. But just how much propane will you need before venturing out? How much propane does an RV furnace actually use?

The simple (and somewhat disappointing) answer is that there is no way to measure exactly how much propane an RV furnace uses. Several factors need to be taken into consideration when estimating how much propane you’ll need to ensure your time on the open road is warm and toasty – including the size of the RV, the size of the furnace, which appliances will use propane for energy, and the length of time you’ll be camping – to name a few.

To calculate how much propane your RV furnace will require, you’ll first need to know its BTU rating. Knowing the number of British Thermal Units (BTUs) will allow you to determine how much heat your particular RV furnace will produce. It goes without saying that the bigger the rig, the bigger the furnace – and the bigger the furnace, the higher the BTU rating (and the more propane it will use). A gallon of propane is just shy of 92,000 BTUs, meaning if your furnace has a BTU rating of 30,000, a gallon of propane will run out after about 3 hours of continuous use (or a total of 184 minutes).

However, it is unlikely that you’ll be running your furnace for 3 straight hours. It may only need to kick on a few times an hour to maintain the internal temperature set on your thermostat, and run for only a few minutes each time. If, for example, the furnace runs four times per hour for two minutes each time (8 minutes total per hour), you can estimate that one gallon of propane will last for about a 23 hour period (184 minutes / 8 minutes per hour), or approximately one day. Since a 20 gallon propane tank only holds about 4.5 gallons of actual propane, it’s safe to estimate a tank of that size will last you approximately 4 and a half days if the furnace is the only thing relying on propane for energy.

Know Your Rig – Getting Acquainted With Your RV and Its Specs

In general, it’s good practice to learn about your RV and its specific features. Besides the propane furnace, many RVs come equipped with a refrigerator, stove, oven, air conditioner and water heater. It is important to know which appliances run on propane and which rely on electricity for energy. Some larger RVs (typically 35 feet and longer) may even have more than one propane furnace to allow for separation between the heating system and other propane-powered appliances, like the stove and water heater. Since all of these factors contribute to the amount of propane used, familiarizing yourself with your rig will allow you to estimate your propane needs more accurately. It’s also important to know what type of propane tank is on your RV. 

Types of Propane Tanks

DOTs: There are two types of propane tanks found on RVs. The first is known as a DOT (Dept. of Transportation) cylinder, which is most commonly found on 5th wheels, travel trailers, and even some small motorhomes. They’re usually mounted on the exterior of the trailer in their own compartment. They can be removed for refilling and can easily be replaced if necessary.

ASME: The other type of tank is known as an ASME (American Society of Engineers) tank. Unlike DOT cylinders, ASME tanks are affixed to the RV and cannot be removed for filling. Both types of tanks are available in 20, 30 and 40 pound varieties, which are the most popular sizes found on RVs.

Size Does Matter: How Different Size Propane Tanks and Furnaces Measure Up

Propane furnaces are typically integrated into a system of ducts and heating vents designed to heat the entire RV, rather than provide heat to specific, localized areas. For this reason, the overall size of the RV will determine the size and number of furnaces required, and consequently, the size and number of propane tanks necessary to provide adequate fuel.

Size of the Furnace: The most common furnace sizes found on RVs are 20,000, 30,000 and 40,000 BTUs. As mentioned in the example above, a 30,000 BTU furnace will consume a gallon of propane in about 3 hours. In other words, it will consume about 1/3 of a gallon of propane per hour of continuous use. Using the same logic, a smaller 20,000 BTU furnace will only use about ¼ of a gallon of propane per hour of continuous use, and the larger 40,000 BTU furnace, about half a gallon per hour.

Size of the Propane Tank: Once you know your furnace size, the next variable that you’ll need to be aware of is the size of the propane tank that will supply the furnace. There are 20, 30 and 40 pound options available depending on the size of the RV and furnace. A 20 pound propane tank is what we typically think of for grills, space heaters, and generators. A 20 pound tank houses about 4.5 gallons of propane, while a 30 pound tank (which is the most common size used on RVs) holds 7 gallons of propane. The 40 pound holds about 9.5 gallons.

Ways to Increase Efficiency When Using Your Propane-Fueled RV Heating System

RV propane furnaces are often thought of as being inherently inefficient because large amounts of heat have a tendency to escape during the process of pulling in the necessary oxygen from the outside air. However, there are ways to increase the efficiency of your furnace and therefore save on propane costs.

Insulation: One obvious way to increase your RV’s efficiency is to ensure that it is well insulated. Better insulation means better heat retention. If more heat is retained within the RV, it will take longer for the temperature to drop below the thermostat setting, meaning your furnace will not need to kick on as often, thus using less propane.

Air Leaks and Drafts: The less cold air that is allowed to creep in, the warmer the RV will stay, so plugging up any spots that might be open is another way to increase efficiency. Seals around windows and doors are the most common places on an RV for there to be air leaks, but most can be easily repaired or plugged using spray foam or a rubber-based sealant. Hanging thermal insulated window coverings and using draft guards on the bottoms of doors can help as well.

Thermostat Setting: Keeping your thermostat at a reasonable temperature is another way to lower heat costs. If you’re camping, but will be engaging in activities away from the campsite during the day, it is not necessary to keep the RV warm until you return. Consider using heavier bedding at night and layering your clothes so that you can adjust the thermostat to a lower temperature setting while you sleep. Installing a ceiling fan can help lower the warm air by running it in reverse.

These small efforts, when combined, could help keep propane costs more manageable.

Alternatives to Using Propane

Although many RVs come already equipped with heating systems and appliances that rely on propane as their energy source, there are some alternatives that can be utilized to supplement your propane use.

Space Heaters: Electric space heaters are compact and lightweight, making them a viable option for heating small, specific areas of an RV. Most people will keep one in the living area during the day and move it to the sleeping quarters at night. When choosing an electric space heater, focus on ones that meet your needs and can be used safely. Ceramic heaters are not only safe and durable, but often include many desirable features like an automatic shut off if the unit is knocked over, a remote control, oscillating capabilities, and several speed settings.

Electric Fireplaces: Some RV’s also come with electric fireplaces that can be used for heat as well as ambiance. There are lots of compact options on the market if your RV does not come with one pre-installed. You could also consider the use of an electric blanket at night.

Using an alternative electric heat source can be the least expensive option to supplement your propane use, especially if you’re camping on a site that gives you access to a free hookup.

Tips, Safety and Best Practices

In addition to implementing the tips noted throughout this article, it’s important to perform proper routine maintenance on your RV furnace to ensure it runs at peak efficiency. Be sure to have it professionally serviced on an annual basis at minimum. It is also recommended to perform the following tasks on a regular basis:

  • Clear all vents of dust, dirt and any other debris that may block airflow
  • Keep other objects away from vents and returns
  • Clean soot buildup off of exterior vents
  • Visually inspect the entire system for areas that need attention or repair

As an additional safety precaution, make sure all smoke, propane and carbon monoxide detectors are in proper working order. If you smell propane and suspect there is a leak, remove all heat and fire sources and exit the RV immediately.

Camping in an RV in cold weather can be equally as pleasant and affordable as camping in the summer if you take the time to get to know your vehicle and understand what’s required to run it properly and efficiently. Using the figures, calculations and tips provided in this article, you can reasonably estimate how much propane you’ll need to be able to run your furnace for your entire trip without running out of fuel.

If you have any experience or advice for camping in colder climates, drop a comment below!

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