How to Winterize Pool Heaters

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Things You'll Need

  • Air compressor

  • Chlorine

  • Scale deterrent

  • Algae prevention additive

Winterize your pool to protect it from freezing temperatures during the cooler months that could cause costly damages to your water lines, pool heater and other devices. Correctly closing up your swimming pool in the fall will also lighten your workload next year when getting it ready for the new swim season. Make sure your pool heater is ready to go next year by following proper guidelines.


Step 1

Winterize the entire pool by removing all chlorine products from the chlorinator and skimmer baskets, vacuuming and brushing the pool, adjusting the pH levels for winter conditions and adding a scale prevention liquid. Pools should also be shocked and super chlorinated and the water level should be adjusted below the skimmer a good 6 inches. Add an algae control additive according to the manufacturer's recommendations.


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Step 2

Drain and plug up all of the plumbing lines that go to and from the pool.

Step 3

Turn off all power to the heater and other units.

Step 4

Remove any drain plugs located inside the heater and drain it of all standing water. Store the drain plugs in the filter basket to keep it safe and accessible for next season. Do the same with the other pool equipment such as the pump strainer, filter, chlorinator and pump body.

Step 5

Blow out any excess water in the pool heater using an air compressor.


It is not recommended to remove the heater tray as it is difficult to reinstall, although it may be necessary on some units. Check your manufacturer’s recommendations. Most pools should be fine leaving the heater tray inside of the unit for the winter season.

Some concrete pools require logging, which helps keep ice expansion from harming the pool. Fill six empty gallon containers a quarter of the way full with gravel and sink at equal intervals down the entire length of the pool’s center.

Before installing plugs, be sure to remove the directional eye assembly that is located in the return lines.


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