Swimming pool heaters are the most complicated piece of pool equipment on you pool equipment pad. Making repairs to pool heaters should be performed by qualified personnel. Gas pool heaters using Natural Gas or LP (Liquid Propane) gas can be hazardous by combustion or exhaust of the pool heater. Hayward pool equipment had created the Pool heater FAQ below to help the pool owner with pool heater repairs and pool heater troubleshooting.

1. Is it switched to On?
2. Is the thermostat set to a higher temperature than current water temp?
3. Is the pump running with a clean filter and baskets?
4. Is the heater gas valve in the on position?
5. Is the pilot lit? (millivolt heaters)
6. Is the gas supply valve open?
7. Are all plumbing and filter valves open?
8. If an external heater bypass is installed, is it properly adjusted?
9. Contact a qualified technician if you still cannot locate the problem.

This could be due to low gas pressure, inadequate air supply, or improper venting. Make sure gas is turned on; and for propane, make sure the tank has fuel. Also check for water run-off from roof or sprinklers that may be flooding the heater. Check to make sure the heater pilot tubing is intact and not clogged. Check that the pilot orifice is not clogged with rust or small insects. For millivolt heaters, if the pilot will not stay lit, check the output of the thermocouple, for 600 mv.

The thermostat may be set too low. If the heat loss is greater than the heater input - the heater may be too small, outside air temperature is too low, or your heater may have an inadequate gas supply. You may want to install a solar pool cover to slow heat loss from your pool. All pool heaters have high limit switches to prevent overheating. A faulty high limit switch could shut off the heater, or the problem could be that the heater is truly overheating, perhaps from improper exhaust out of the top of the heater.

Your heater may have inadequate water flow due to a dirty filter, closed valve, external bypass, reversed water connections, or pressure switch out of adjustment. It is also possible that your thermostat is out of calibration or needs to be replaced. For low speed or variable speed pumps, the heater will not work on low flow pump speeds.

See previous two questions for additional information. Also check for water run off from above or sprinklers directed at heater. A high wind stack may be needed due to heater location. Millivolt models have a thermocouple or pilot generator that may be faulty or weak. Loose or rusty connections of the thermocouple to the gas valve or loose coil connection, or a short in these wires can shut off a pilot.

Getting the pilot to light is half the battle. If it’s trying to light but either won’t light the pilot, or won’t light the burner tray, there could be a multitude of reasons. Refer to your pool heater owner's manual. Make sure that the heater gas valve is in the on position, and if LP (Propane) is being used, check the gauge on the tank.

The pool heater heat exchanger may be leaking because of chemical or sanitizer damage. The damage may be from winter freeze - usually leaking upon spring start-up, and usually on the return manifold, aka rear header. There could be a gasket leaking, or a loose connection to the pressure switch. Finally, a drain plug could be loose, or missing an o-ring.

This may be caused by condensation (occurring when heating very cold water); a missing or damaged internal bypass in the front header; or excessive water flow through the heater from an oversized pump. Check the heat exchanger for a buildup of soot and make sure the internal bypass is working (located inside of the front header). For high speed pumps, installing an external pool heater bypass may be necessary to reduce the water flow coming into the heater.

This is caused by either low gas pressure and/or inadequate air supply and venting. It could be that leaves or debris is blocking the intake vents around the heater sides or the exhaust through the top. Review the installation requirements in the pool heater Owner's Manual. Both conditions may need to be evaluated by a qualified service technician. Sooting indicates improper combustion and could lead to other problems or hazards.

One, or a combination of the following: low gas pressure, down-drafting, air supply, and venting. Older pool heaters may need a high wind stack, if installed near a vertical wall or windy area. Make sure that the heater is installed with proper clearances all around the outside. Pool Heaters can catch adjacent structures on fire, and pool heaters should not be located near windows, where carbon monoxide from the pool heater could be drawn into the house. If you notice a ‘hot spot’ on the side of the heater, the insulation in that area may have deteriorated or been stolen by varmints!

Sanitizers or acidic water conditions can deteriorate protective coatings on heater components and create rust. If you find rust bits below the returns, usually a cast iron heater header or exchanger flange is the rusty culprit. Re-balance chemicals with special attention to correct pH and alkalinity levels. Make sure any chemical feeders or salt systems are installed after the heater, and place a check valve between the heater and chlorinator to prevent backflow of highly chlorinated water into your pool heater. You aren’t putting chlorine tablets into the skimmer are you?

Low gas pressure can cause whistling in the burners. Check your Owner's Guide or contact your installer. It can also be attributed to partially clogged burner orifices. These can be reamed out (with the heater off), with a small paper clip, or bit of bent wire.

No. Hayward heaters cool down immediately after shut down. It is however, good practice to turn off a firing pool heater in advance of shutting off the pool pump. Heat sinks are steel or copper pipes that are connected to the in and out ports of the heater header. These absorb heat, taking it out of the heater, when a firing heater is suddenly shut off (manually or by a timer). A fireman’s switch is a device that attaches to an Intermatic time clock, to shut off the heater 20 minutes before the time clock shuts off the pump.

All heaters should be installed on a non-combustible material, such as concrete or block. It must not have any structures above it, including roof eaves, stairs, and tree branches – just clear blue sky above. Consult owner's manuals for specific and important information about installing pool heaters indoors (don’t do it). Around all four sides of your heater, at least 24” should be open and clear, and in the front, 48” of clearance for working on the heater in the future. Don’t install a pool heater below any windows or next to any doors which could draw in the carbon monoxide exhaust. A sunny dry location is best, cleared of all vegetation, and away from automatic sprinklers. Don’t mulch around the bottom of the heater, but keep the air flow free.

Yes, specific conditions apply. Please consult your owner's manual for complete details. Indoor pool heaters must be vented to the outside in a very specific manner, and have enough influent air to combust properly. Carbon Monoxide detectors should be used and maintained. Improperly installed or maintained indoor pool heaters have the potential to cause fatalities from carbon monoxide emissions. Many people have been killed or injured by improperly vented heaters, or from leaking vent pipes, deteriorated over the years.

Propane pool heaters use one gallon of fuel per hour for each 91,000 BTU's of heater input. Example: A 250,000 BTU heater uses: 250,000/91,000 = 2.75 gallon per hour. Natural gas heaters use one therm (100,000) BTU per 100,000 BTU's heater size. Gas invoices are usually billed by therms. Natural gas is cheaper than propane gas, if you can get it. If your neighborhood is not ‘cooking with gas’, LPG can be delivered to an on-site storage tank.

1. Purchase an energy efficient pool heater.
2. Use a solar pool cover or automatic cover to retain heat.
3. Keep the temperature at the lowest comfortable position.
4. Setting the heater to maximum will not heat faster, and risks overheating.
5. Turn heater off or to a lower setting during periods of non-use.
6. Wind is one of the largest heat thieves. Use fence or shrubs as wind blocks.

1. Keep a thermometer in your pool to find the temperature most comfortable for you.
2. Keep your thermostat at the lowest comfortable setting.
3. Mark the "comfort setting" on the thermostat dial, for quick reference.
4. Lower thermostat to 70 degrees when pool is to be unused for three or four days. For longer periods, shut the heater off.
5. Protect your pool from wind. Wind above 3 to 5 miles per hour can lower the pool temperature substantially. A hedge, cabana or decorative fence can be an effective windbreak.
6. Use a pool cover when pool is not in use. This can reduce heat loss by as much as 90%.
7. If you are vacationing for a couple of weeks or shutting down for winter, turn the heater off completely, including any pilot light.
8. Drain heater completely prior to freezing weather. Freezing water inside the heat exchanger can result in costly repairs.

Keep your heater clean and as dry as possible. Sweep out beneath the burner tray and clean any leaves off of the heat exchanger. Trim back foliage around and above the heater for wind and sun to reduce moisture. Don’t mulch around the heater, which traps moisture.

Keep rodents out by using mint sachets or moth balls during winter. Nesting rodents can strip out insulation and chew on wires. Investing in a winter pool heater cover is also a good idea to keep out the elements and rodents.

Pool heaters out in the weather typically last for around 15 years. At some point, an expensive repair such as a new heat exchanger or another pilot / gas valve will have you weighing the benefits of a new pool heater. Replacement pool heaters should be installed by a qualified person; and it’s especially wise to hire a qualified gas contractor to make the gas connection.

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