Yes, you absolutely need to winterize your pool heater if temperatures drop below 40°F in your area. Failing to properly winterize can cause expensive freeze damage to internal components and plumbing lines.
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Yes, you absolutely need to winterize your pool heater if you live in an area where temperatures drop below 40°F (4°C). Pool heaters contain water-filled pipes and components that can freeze and crack, leading to expensive repairs costing hundreds or thousands of dollars. Even if you keep your pool open during winter, the heater itself requires winterization when not in use.
Pool heaters are particularly vulnerable to freeze damage because they contain numerous water passages, heat exchangers, and plumbing connections. When water freezes, it expands by approximately 9%, creating enough pressure to crack metal pipes, damage heat exchangers, and destroy internal components. This is true for all heater types including gas, electric, and heat pump units.
The most common freeze damage occurs in the heat exchanger, which can cost $800-2,000 to replace depending on your heater model. Water lines, unions, and pressure switches are also frequently damaged, adding to repair costs.
Begin winterization when nighttime temperatures consistently drop below 40°F, even if daytime temperatures remain warm. Many pool owners make the mistake of waiting until the first hard freeze, but damage can occur at temperatures above freezing if water sits stagnant in the system.
If you're closing your pool completely, winterize the heater as part of your overall closing process. For pools remaining open during winter, you can winterize just the heater while keeping the rest of your system operational.
Turn off the gas supply at both the heater and the main gas valve. Wait at least 10 minutes for any residual gas to dissipate before beginning work. Ensure the heater has been off for several hours so internal components are cool.
Turn off the electrical breaker supplying power to the heater. Most gas heaters have electronic ignition systems and control boards that should be protected from power surges during winter months.
Remove the drain plugs located at the bottom of the heater housing. Most Pentair, Hayward, and Raypak heaters have 2-4 drain plugs. Store these plugs in the equipment area so you don't lose them. Open the pressure relief valve if your unit has one to ensure complete drainage.
Disconnect the water supply and return lines at the heater unions. This prevents any water from flowing back into the unit from the pool plumbing. Use a wet/dry vacuum to blow out any remaining water from the heat exchanger and internal passages.
Cover the heater with a waterproof cover designed for your specific model, or use a tarp secured with bungee cords. Ensure ventilation openings remain unobstructed to prevent moisture buildup and corrosion.
Electric resistance heaters and heat pump units require similar winterization steps with some important differences. These units often have more complex refrigeration systems (in heat pumps) that require special attention.
For heat pump units, the refrigeration system should be professionally serviced before winter storage. The water circulation system is drained using the same process as gas heaters, but pay special attention to the titanium heat exchanger, which can be damaged by freezing.
Electric resistance heaters have heating elements that can crack if water freezes around them. Ensure complete drainage and consider removing the elements for storage in a warm, dry location.
In moderate climates where temperatures only occasionally drop below freezing, you may not need full winterization. However, you should still drain the heater and disconnect water lines during cold snaps. Some pool owners in these areas install freeze protection systems that automatically circulate water when temperatures drop.
In northern climates with extended freezing periods, complete winterization is essential. Consider having your heater professionally serviced in fall to address any issues before winter storage.
Proper winterization makes spring startup much easier. Before restarting your heater, reinstall all drain plugs with new gaskets or O-rings. Reconnect water lines and slowly fill the system, checking for leaks at all connections.
Have the gas connections inspected by a qualified technician before first use. Many manufacturers require annual inspections to maintain warranty coverage.
The biggest mistake is assuming that running the heater occasionally during winter prevents freeze damage. If water sits in the system between uses, it can still freeze. Either use the heater continuously or winterize it completely.
Another common error is forgetting to drain auxiliary components like bypass valves and pressure switches. These small components are expensive to replace and frequently overlooked during drainage.
Never use antifreeze in pool heaters unless specifically designed for the purpose. Automotive antifreeze is toxic and can damage heater components.
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