Swimming Pool Blog

Gas Pool Heater Safety

by Rob Cox, June 12, 2010

Gas Pool Heater Safety

natural gas molecul


An estimated 900,000 pools in the U.S. are heated by Natural Gas or Liquid Propane Gas. Both heaters will operate identically, only the fuel is different. Molecularly, both Natural & Propane gas is a mixture of Carbon & Hydrogen, but after refinement, Natural Gas is really closer to Methane Gas.

Both Natural & Propane gas in their natural state are odorless. To make people aware of a gas leak, gas companies add a touch of something sulfurous, like mercaptan, to give strong evidence of it's presence. The smell of gas is something not unlike rotten eggs, skunk spray or a dead animal.

Older adults or those with a reduced sense of smell should install a gas detector to alert them in the event of a gas leak emergency. And every gas leak, no matter how small, is an emergency.

Here's some tips to make sure that you avoid any injuries from your pool heater.

1. Gas Pool Heaters create Carbon Monoxide

Vitas Guerulaitis was in fact killed by his pool heater, overcome by Carbon Monoxide, which crept into his room while he slept. Proper installation of this pool heater could have prevented this and other fatalities from the odorless gas. Placement of a pool heater beneath or near any windows or doors is not a good idea, and if it must be installed indoors, properly maintained exhaust venting must be attached to the heater.

If your pool heater is beneath a window, up against the house, consider moving it or nailing the window shut. If your pool heater is located inside a shed, or even worse, in the basement, install carbon monoxide detectors nearby. Over time, exhaust venting can become loose, birds may build nests in the vent stack, or your heater could begin to exhaust gases out of the side. It takes very little time to fill a room or shed with fatal levels of carbon monoxide. You can't smell CO, but if you do smell heater exhaust, chances are you are inhaling CO gas.

2. Gas Pool Heaters can Catch Fire

Flame Roll-Out is the term used when flames "roll-out" of the front or sides of the heater.  This can happen if ignition does not happen soon enough while the burners are filling with gas. Clogged or block burners, improper pilot position, or faulty components can all cause delayed ignition and flame roll out. If enough gas is present, your heater can actually explode, blowing the door off.

If heaters don't exhaust fast enough, due to clogged heat exchanger fins or debris on top of the heater, this can also cause the flames to roll out. On older heaters that has lost some insulation, flame can exit the sides or top of the heater, and some structures have been lost. 

3. Gas Pool Heaters can Leak Gas 

At any connection point from the gas meter or gas tank to the pool heater a leak can develop. If you smell gas, call your gas company immediately to report a gas leak emergency. They may assist you on the phone with finding the valve and turning off the gas supply. It is not uncommon to smell small amounts of propane coming from the relief valve of a propane tank. Natural gas should not smell at all - so any small leak should be reported.

To test for gas leaks around connections and fittings, one can use a small bottle of soapy solution. Any bubbles forming will indicate a leak. Important to note that while Natural Gas is lighter than air, LP gas is heavy and will "pool" on the floor of a heater or a small pump area. This is what makes propane pool heaters a bit more "explosive" than natural heaters.