Home › Natural Gas vs Propane Pool Heater

Natural Gas vs Propane Pool Heater

Same heater, different fuel

Most gas pool heaters are built in natural gas and propane versions, and some can be converted with a manufacturer kit installed by a qualified technician. Burner orifices, gas valves and pressure settings differ because propane is supplied at different pressure and has a different energy content. Never swap fuels without the correct kit and a licensed professional.

Energy content and unit prices

Natural gas is commonly billed in therms (100,000 BTU), cubic metres or gigajoules depending on your utility. Propane is billed by the gallon (about 91,500 BTU) or litre (about 24,000 BTU). To compare fairly, convert both to cost per 100,000 BTU of fuel:

• Natural gas: price per therm.
• Propane: price per gallon × 100,000 ÷ 91,500, or price per litre × 100,000 ÷ 24,000 roughly.

Then divide by heater efficiency to get the cost per 100,000 BTU delivered to the water. The operating cost calculator handles both fuels.

Installation differences

• Natural gas: requires a utility connection with enough meter and pipe capacity for the heater's full input plus other appliances. A long run from the meter may need larger pipe or a meter upgrade from the utility.
• Propane: requires a tank sized for the heater's demand and refill schedule, placed at code-required distances from buildings and openings, with a regulator and line. Large heaters can draw tanks down quickly in cold weather, so tank size matters. Tank rental or purchase terms vary by supplier.

Both must be installed by licensed professionals and usually inspected. Gas work is never DIY.

Running cost reality

Where natural gas is available, it is often cheaper per BTU than propane, but local markets vary and prices change by season. Propane prices can swing more, and delivery minimums and tank rental fees add to the real cost. For heavy pool heating, those differences add up quickly. For occasional heating, convenience and installation cost may matter more than the fuel price.

When propane makes sense

Rural homes without gas service, cottages, and properties where running a gas line would be very costly often choose propane. If you already have a propane tank for other appliances, adding a pool heater may only require a larger tank and a line. In those situations, also compare against an electric heat pump; see heat pump vs gas pool heater.

When natural gas makes sense

If a gas line is near the pool equipment and the meter has capacity, natural gas is usually simpler and cheaper to run. The main cost question becomes the pipe run and any meter upgrade.

Worked example

Figures below are illustrative examples (2026-10-29), not quotes or guarantees.

Assumptions: the pool needs 12 million BTU delivered a month, heater efficiency 84%. Natural gas at $1.40 per therm: 12,000,000 ÷ 0.84 ÷ 100,000 ≈ 143 therms ≈ $200. Propane at $3.00 per gallon: 12,000,000 ÷ 0.84 ÷ 91,500 ≈ 156 gallons ≈ $468. At these assumed prices propane costs more than twice as much per month; your local prices decide the real gap.

Safety

Both gases are flammable. Propane is heavier than air and can collect in low spots; natural gas is lighter and rises. Both have odorants added. If you smell gas, leave the area, avoid switches and flames, and call your utility or propane supplier from a safe place. Keep vents and burner areas clear and book annual service.

Converting an existing heater

If you switch from propane to natural gas when a gas line arrives, ask your installer whether your heater model supports a conversion kit and what the cost would be compared with a new heater. Conversions must be done by a qualified technician and labelled correctly.

Questions to ask your fuel supplier

• What is the current price per gallon, litre or therm, including delivery and fixed charges?
• Are there minimum delivery amounts or tank rental fees for propane?
• Is the gas meter large enough for an added pool heater?
• Are there seasonal price programs or budget plans?

Planning with both options

If you are building a new pool and have the choice, ask your installer to price both fuels plus a heat pump. Factor in five or more seasons of running cost from the calculator. The best answer for a daily-use family pool can differ from the best answer for a cottage pool used on summer weekends.

Tank sizing in plain terms

Propane draws from a tank by vaporizing liquid, and the rate a tank can vaporize depends on its size, how full it is and the outside temperature. A large pool heater firing for hours can outpace a small tank, especially on cool days, causing low pressure and poor burner performance. That is why propane suppliers size tanks for heater input, not just monthly gallons. Expect your supplier to ask for the heater's BTU input and how many hours you plan to run it. Larger tanks also mean fewer deliveries, which can lower delivery fees.

Environmental notes

Both fuels release carbon dioxide when burned; per unit of heat, propane and natural gas are in a similar range. Methane leaks from gas systems are a separate concern. If reducing fuel use is your goal, a cover helps most, and an electric heat pump can lower on-site combustion entirely. Whatever fuel you use, a well-maintained heater burns cleaner and more efficiently.

Combining with solar or a heat pump

Some owners keep a propane heater only for quick boosts and use solar or a heat pump for daily heat, which cuts propane deliveries sharply. Controls can prioritize the cheaper source. Ask a pool professional to design the plumbing order and settings.

FAQ

Is propane less efficient than natural gas?

The heater efficiency is similar; the difference is fuel price and supply.

How big a propane tank do I need?

It depends on heater input and use; your propane supplier sizes it.

Can I convert my heater myself?

No. Conversion kits must be installed by a qualified technician.

Try the calculator · Back to FAQ & guides