RV propane supply: estimate use from actual fuel and loads
Estimate propane runtime from the fuel supplied and the appliance’s fuel-input rating, then include every other propane load and operating time. A cylinder’s nominal capacity is not proof it was filled with that amount. Do not promise a fixed number of camping days from the cylinder size.
Use one stated energy conversion
The US Energy Information Administration’s conversion table lists 91,452 BTU per US gallon of propane. Fuel composition affects conversion factors. Use the known quantity from your supplier rather than treating a tank’s total water capacity as usable propane volume.
| Calculation | Result |
|---|---|
| 4 × 91,452 | 365,808 BTU nominal fuel energy |
| 365,808 ÷ assumed 30,000 BTU/h input | 12.2 hours of continuous burner operation |
| 12.2 ÷ assumedone-third duty cycle | 36.6 elapsed hours before other loads or reserve |
The assumed furnace duty cycle is not a measured winter forecast. Wind, insulation, thermostat setting and other loads change consumption. Divide by fuel input, not delivered heating output, unless the corresponding efficiency is accounted for.
Plan reserve rather than using the arithmetic as a deadline
Record refills and actual use in comparable conditions. A hot-water appliance or range draws from the same supply, and colder weather can change both consumption and the cylinder’s ability to deliver vapor. The calculation above does not promise the full nominal energy remains available at every temperature.
For a two-cylinder arrangement, learn the exact changeover indicator and procedure before departure. An automatic regulator switching sides is not a refill, and leaving both cylinders depleted defeats the intended reserve.
A regulator is not an owner-adjustable performance control
Match the installed regulator, supply and appliance requirements through qualified service. Poor flame, unusual sound or loss of performance does not establish one faulty component or a universal replacement age. Do not heat a cylinder or alter regulator pressure to increase supply.
PERC’s safety instructions require leaving immediately for a gas smell or alarm and reporting the suspected leak from a safe place. Do not stay inside testing appliances to decide whether the regulator is at fault.
Check refill eligibility before the supply runs out
Removable DOT cylinders and fixed ASME tanks have different markings and inspection requirements. The current federal cylinder rule distinguishes specification, service and qualification method. Have an authorized filler assess the actual cylinder and condition.
Use cylinder dates and refill safety before a trip. At a tunnel, ferry or fuel stop, follow the operator’s current restrictions and the installed appliance instructions. The ability to carry a fuel supply does not authorize a flame near refueling operations.