How Much Propane Does a Camper Furnace Use

The article explains how much propane a camper furnace typically uses, how to estimate consumption, and practical tips to stretch fuel while staying comfortable and safe. It covers furnace BTU ratings, conversions to gallons and pounds, real-world examples, and factors that change fuel use so readers can plan trips and manage propane reserves confidently.

Furnace Size (BTU/hr)	Gallons Per Hour (Continuous)	Pounds Per Hour	Approx. 8-Hour Night Use (Gallons)
10,000	0.11	0.47	0.88
20,000	0.22	0.93	1.76
30,000	0.33	1.40	2.64
40,000	0.44	1.86	3.52

How Propane Consumption Is Calculated

Propane consumption for a furnace is based on the furnace’s heat output in BTU per hour and the energy content of propane. One liquid gallon of propane contains about 91,500 BTU. To estimate raw fuel consumption, divide the furnace BTU/hr rating by 91,500.

Example formula: (Gallons/Hour) = Furnace BTU/hr ÷ 91,500. To convert gallons to pounds, use 1 gallon ≈ 4.24 pounds.

Typical Camper Furnace Ratings And Baseline Use

Common RV/camper furnaces are rated between 10,000 and 40,000 BTU/hr. Many manufacturers list popular mid-range models at 20,000 to 30,000 BTU. Using the conversion above, a 20,000 BTU furnace running continuously would use about 0.22 gallons per hour, and a 30,000 BTU furnace about 0.33 gallons per hour.

Real-World Use: Cycling, Thermostat, And Duty Cycle

Furnaces rarely run full continuous output. They cycle on and off to maintain a set temperature. The actual fuel used depends on the duty cycle: the percentage of time the burner is on. A typical duty cycle might range from 25% to 75% depending on outside temperature, insulation, and thermostat setting.

If a 30,000 BTU furnace has a 50% duty cycle, effective consumption is 0.33 × 0.5 = 0.165 gallons per hour. Over an 8-hour night that equals about 1.32 gallons.

Sample Calculations For Planning

These quick examples help plan propane needs. Example A: A 20,000 BTU furnace with a 40% duty cycle uses 0.22 × 0.4 = 0.088 gallons/hour, or about 0.7 gallons over 8 hours.

Example B: A 40,000 BTU furnace in cold weather with a 70% duty cycle uses 0.44 × 0.7 = 0.308 gallons/hour, or about 2.46 gallons over 8 hours.

Factors That Affect Propane Use

• Outside Temperature: Colder conditions raise duty cycle and consumption.
• Insulation And R-Value: Better insulation reduces heat loss and run time.
• Thermostat Setting: Each degree higher increases energy needed to maintain the interior temperature.
• Wind And Air Leakage: Drafts and vents increase heat loss and burner on-time.
• Altitude: Combustion efficiency can change slightly at high altitudes; furnaces may run longer.
• Furnace Efficiency: Older or poorly tuned units can use more propane to achieve the same comfort.

Tank Sizes And How Long They Last

Common portable propane bottles for campers are 20 lb (about 4.7 gallons) and 30 lb (about 7.1 gallons). Motorhomes may have two 20 lb cylinders or bulk tanks (e.g., 60–100 gallons). Using the earlier tables, a 20,000 BTU furnace running at a 50% duty cycle at night uses ~0.11 gallons/hour; a 4.7-gallon 20 lb bottle could supply roughly 42 hours of stove-equivalent continuous use, but in practical cycling furnace terms that might translate to many nights.

Practical Nighttime Estimates

For typical overnight planning, assume 8 hours of nighttime operation. Using a mid-range 25,000 BTU furnace with a 50% duty cycle, approximate use is 0.27 × 0.5 = 0.135 gallons/hour, or about 1.08 gallons per 8-hour night. A 20 lb (4.7 gallon) tank would cover roughly four such nights.

How To Read Propane Gauges And Estimate Remaining Fuel

Propane gauges on RVs often display percentage levels, but these can be inaccurate unless the tank sits level. To estimate gallons remaining: multiply tank capacity (gallons) by gauge percentage. For a 20 lb bottle (4.7 gal) at 50%, remaining fuel ≈ 2.35 gallons. Always keep a safety margin—don’t run to empty while heating.

Tips To Reduce Furnace Propane Consumption

• Lower thermostat by a few degrees and use warm bedding; each degree can significantly cut run time.
• Use foam insulation, window covers, and draft stoppers to reduce heat loss.
• Service the furnace yearly: clean burners, check seals, and verify correct operation to improve efficiency.
• Consider a small electric space heater when shore power is available, which may be cheaper if electricity is free or included.
• Use a programmable or smart thermostat to minimize run time while maintaining comfort.
• Close vents and doors to heat only occupied areas of the camper.

Safety And Best Practices When Using Propane For Heat

Propane furnaces produce combustion byproducts and require ventilation and working carbon monoxide (CO) and smoke detectors. Always follow manufacturer installation and maintenance instructions.

Key Safety Points: Keep propane tanks upright and secured; check fittings for leaks; ensure exhaust flues are clear; never run a furnace with the door or vent blocked; test CO detectors regularly.

When To Refill Or Carry Extra Propane

Plan refills before levels drop below 25% for peace of mind in cold conditions. Carry an extra certified cylinder if traveling in remote areas or during extended cold spells. For motorhomes with bulk tanks, monitor the gauge and refill at professional stations.

Advanced Considerations: Efficiency, BTU Needs, And Alternatives

Home-style furnaces measure seasonal efficiency (AFUE), but RV furnaces have limited ratings. For precise planning, measure actual run time over a cold night and calculate consumption from tank level change. Alternatives to reduce propane use include supplemental insulation, 12V heated blankets, or a catalytic heater designed for indoor use per manufacturer guidance.

Common Myths And Misunderstandings

Myth: Larger BTU rating always means more cost—Reality: Higher BTU can heat faster and cycle less, sometimes reducing total fuel use in short bursts. Myth: Propane gauge accuracy is perfect—Reality: Gauge readings vary with temperature, tank orientation, and gauge quality.

Quick Reference Calculation Tool

Steps To Estimate Consumption: 1) Find furnace BTU/hr from manual. 2) Decide expected duty cycle (%) for conditions. 3) Gallons/hour = (BTU/hr ÷ 91,500) × duty cycle. 4) Multiply by hours to get total gallons. 5) Compare to tank gallons to find how many nights or hours remain.

Maintenance Checklist To Keep Propane Use Low

• Annual professional furnace service and combustion efficiency check.
• Clean or replace air filters and test thermostat accuracy.
• Seal gaps and replace worn door or window seals.
• Inspect propane hoses and fittings for leaks and wear.
• Keep venting and flues clear of debris and snow.

Useful Conversion Reference

Measure	Equivalent
1 Gallon Propane	~91,500 BTU | ~4.24 Pounds
1 Pound Propane	~21,600 BTU | ~0.236 Gallons

Final Planning Tips

When planning a trip in cold weather, gather furnace BTU specs, tank capacities, and typical nighttime temperatures. Run the calculation tool above and add a conservative buffer of 20–30% to avoid running out. Regular maintenance, insulation improvements, and small behavior changes will yield significant propane savings and improve safety and comfort.