How Much Does It Cost To Heat A Pool With Gas?




Before you commit to buying ANY pool heater you need to be aware of the cost to run the heater. Gas, particularly natural gas, is one of the cheaper fuels to use in pool heating but it does still cost! Once you have worked out what size gas pool heater you need it is an easy step to work out the ongoing running cost.

To work out the cost of running a pool heater by the hour you need to know a couple of things:

  • Input BTU for the heater  -  this is the figure you usually see to rate the heating capacity of a pool heater (eg. The Jandy LXi 250k will USE 250k BTU of gas per hour to PRODUCE 220K  BTU per hour of heat at 88% efficiency)
  • The cost per BTU or Therm of the gas available to you

To make things a bit clearer, lets run through an example. If we use the Jandy LXi 250k BTU unit from above we know the gas consumption is 250k BTU per hour.  Now we need to know how much your gas will cost you per therm (which is 100,000 BTU or 100k BTU) or per cubic foot which you often see as mcf (thousand cubic feet) or ccf (hundred cubic feet). For example, your gas company may supply you natural gas at a cost of $4.40 per mcf which is $4.40 per thousand cubic feet. Your bill may read gas use in therms which is kind of handy because one therm = 100,000 (or 100k) BTU = 100 cubic feet ( or 1 ccf) of natural gas (almost) and 10 therms = 1,000,000 BTU (1,000k BTU) = 1,000 cubic feet (1 mcf) of natural gas. From this we can see that a cubic foot of natural gas produces about 1,000 BTU (or 1k BTU).


So what does it cost to run? We’re almost there. That Jandy heater will require 250k BTU per hour meaning you will burn about 250 cubic feet of natural gas. A thousand cubic feet (or 1 mcf) of natural gas costs $4.40 and 250 cubic feet is a quarter of a thousand so a quarter of $4.40 is $1.10. Your Jandy LXi 250k BTU heater will cost you around $1.10 per hour of operating time running on natural gas.


Propane or LPG which is normally supplied via a tanker truck to fill bottles or a tank on your property works out a bit differently. Firstly it produces 2,500 BTU per cubic foot of gas or about two and a half times as much as a cubic foot of natural gas. Secondly, the cost of propane is usually given per gallon with tank sizes for pool heating normally being 120 gallons, 250 gallons or 500 gallons. The price can vary considerably but should be around $2.00 to $2.50 per gallon. One gallon of propane becomes about 37 cubic feet of the expanded gas. One ccf = about 2.7 gallons and one mcf = about 27 gallons.


The same heater will still need 250k BTU per hour which means 100 cubic feet (1 ccf) of propane at 2,500 BTU (2.5k BTU) per cubic foot (100 x 2,500 = 250,000 or 250k. So if your propane costs $2.50 per gallon that means about seven cents per cubic foot or seventy cents per ccf (hundred cubic feet) so the Jandy LXi heater will cost about $0.70 per hour to run on propane. Don’t forget you need to figure in any applicable delivery fees or bottle/tank hire your local propane supplier may charge.

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