How Much Propane Does an Rv Furnace Use Per Hour

An RV furnace’s propane use depends on its BTU rating, run-time, and efficiency. This article explains how to calculate propane consumption, provides practical examples for common RV furnaces, and offers tips to extend heating time and reduce fuel use. It helps RV owners plan trips and manage onboard propane.

Furnace Input (BTU/hr)	Approx. Gallons Per Hour (Input ÷ 91,500)	Gallons Per Hour At 80% Duty Cycle	Hours From A 20 lb Tank (4.7 gal) At 80% Duty
6,000	0.066	0.033	143
16,000	0.175	0.088	53
20,000	0.219	0.110	43
30,000	0.328	0.164	29

How Propane Consumption Is Calculated

Propane energy content is commonly taken as about 91,500 BTU per gallon. The basic formula to estimate consumption is: Gallons Per Hour = Furnace Input (BTU/hr) ÷ 91,500. This calculates the theoretical liquid propane used to deliver the input heat, before accounting for cycling and real-world factors.

Most RV furnaces don’t run continuously at full input rating; they cycle to maintain temperature. A realistic estimate multiplies the theoretical consumption by the furnace’s actual duty cycle (the fraction of time the burner is on). A typical duty cycle in cold weather might be 60–80% when maintaining a set temperature.

Common RV Furnace Sizes And Real-World Fuel Use

RV furnaces often range from about 6,000 to 35,000 BTU/hr input. Below are typical examples using straightforward math and an assumed usage pattern:

• 6,000 BTU/hr: 6,000 ÷ 91,500 = 0.066 gal/hr. At a 50% duty cycle, ~0.033 gal/hr.
• 16,000 BTU/hr (common small RV): 16,000 ÷ 91,500 = 0.175 gal/hr. At a 50–60% duty cycle, ~0.088–0.105 gal/hr.
• 20,000 BTU/hr (typical medium RV): 20,000 ÷ 91,500 = 0.219 gal/hr. At 60% duty, ~0.132 gal/hr.
• 30,000 BTU/hr (large RV or cold climates): 30,000 ÷ 91,500 = 0.328 gal/hr. At 70% duty, ~0.230 gal/hr.

Understanding Duty Cycle, Thermostat, And Ambient Conditions

Duty cycle influences real consumption more than rated BTU. In mild weather the furnace may fire briefly and cycle off, producing a low duty cycle. In very cold weather the furnace may run nearly continuously, increasing propane use toward the theoretical maximum.

Thermostat settings matter: higher set temperatures increase run time. Insulation quality, skirting, roof vents, and air leaks also affect how often the furnace must run. Wind and humidity can further raise heat loss, requiring more propane.

Propane Tank Sizes And How Long They Last

Common portable RV cylinder sizes are 20 lb, 30 lb, and 40 lb. A 20 lb cylinder typically contains about 4.7 gallons of usable propane. A 30 lb cylinder holds ≈7.0 gallons; a 40 lb cylinder ≈9.4 gallons.

Using the example of a 16,000 BTU furnace with an effective use of 0.09 gal/hr (moderate duty), a 20 lb tank (4.7 gal) would last about 52 hours. A 30 lb tank at the same rate would last ≈78 hours. Larger onboard tanks and dual-tank systems extend run time significantly.

Examples: Trip Planning Scenarios

• Weekend Winter Trip: A 16,000 BTU furnace with ~0.09 gal/hr over 48 hours uses ≈4.3 gallons. A single 20 lb cylinder (4.7 gal) can cover this scenario if fridge and stove use are minimal.
• Extended Cold-Weather Travel: A 20,000 BTU furnace at ~0.13 gal/hr over a week (168 hours) would use ≈21.8 gallons. That requires multiple tanks or a larger onboard tank.
• Intermittent Use/Night Heating: Many users run the furnace mainly at night. Running a 16,000 BTU furnace for 12 hours nightly at 0.09 gal/hr uses ≈1.1 gal per night.

Other Propane Uses In An RV To Consider

Furnace use is only part of total propane consumption. Hot water heaters, ranges, and refrigerators (if not electric) also use propane. Add their consumption estimates when planning. For example, a typical RV water heater might use 10,000–12,000 BTU per hour while firing.

Continuous pilot lights (older systems) burn a small continuous amount of propane; modern electronic ignition systems eliminate this, saving fuel. Consider appliance ignition types when calculating total propane draw.

Practical Tips To Reduce Furnace Propane Use

• Increase insulation and use RV skirting to reduce convective heat loss.
• Use a programmable thermostat or lower setpoint at night.
• Close vents and curtains to reduce heated volume and heat loss through windows.
• Service the furnace regularly for proper combustion and efficiency.
• Consider electric supplements (electric blanket, portable electric heater with shore power) when available to reduce propane draw.

Safety And Maintenance Considerations

Proper installation and maintenance are essential. Regularly inspect vents, ducting, the combustion chamber, and the flue to avoid carbon monoxide risks and maintain efficiency. Install and test CO and propane leak detectors in the RV.

Never store extra propane cylinders inside the RV’s living area. Follow manufacturer guidelines for cylinder mounting and replacement. If uncertain about repairs or leaks, consult a certified RV technician or qualified propane service.

Quick Formula And Step-By-Step Calculation

Step 1: Identify the furnace input rating (BTU/hr) from the furnace label. Step 2: Calculate theoretical gallons/hr: Gallons/hr = Input BTU/hr ÷ 91,500. Step 3: Estimate duty cycle (e.g., 0.5 for 50%). Multiply to get realistic gallons/hr. Step 4: Divide tank gallons by gallons/hr to get hours available.

Example: 20,000 BTU furnace, 70% duty: 20,000 ÷ 91,500 = 0.219 gal/hr; real use = 0.219 × 0.70 = 0.153 gal/hr. 30 lb tank (≈7.0 gal) ÷ 0.153 = 45.7 hours.

Frequently Asked Questions

Does furnace efficiency affect propane use?

Measured furnace efficiency affects how much of the input BTU becomes usable heat, but propane consumption is based on input energy. A poorly maintained furnace may need to run longer, increasing consumption despite the same input rating.

How does using electric heating affect propane needs?

Using shore power or a generator to run electric space heaters reduces propane use by shifting heating load to electricity, but consider electrical capacity and cost tradeoffs.

Are there quick ways to estimate tank life without calculations?

A rough rule of thumb: small furnaces in cold weather may use 1–2 gallons per day; moderate furnaces 2–4 gallons per day; large systems more than 4 gallons per day. These are estimates and vary widely with conditions.

Resources And Further Reading

For technical data on propane energy content and safety, consult resources such as the Propane Education & Research Council and the U.S. Department of Energy. For appliance-specific details, refer to the RV furnace owner’s manual.

By using the formulas and examples above, RV owners can better predict furnace propane consumption, size supplies appropriately, and take steps to stretch fuel during cold-weather trips.