Protecting the coils of your heat pump water heater from freezing is crucial, especially in climates where temperatures frequently drop below freezing. The efficiency and longevity of your heat pump water heater significantly depend on the proper functioning of these coils, which are responsible for transferring heat. When water or moisture present in the air freezes on the coils, it can cause damage, reduce efficiency, and potentially lead to system failure. This guide offers comprehensive strategies to prevent coil freeze and maintain the optimal performance of your heat pump water heater.

Understanding Coil Freeze in Heat Pump Water Heaters

Heat pump water heaters operate by extracting heat from the air and transferring it to the water. This process involves the evaporation and condensation of refrigerant within the coils. During colder months, the outside air can cause the temperature of these coils to drop below freezing, leading to ice formation. Not only does this ice accumulation reduce the system's ability to heat water efficiently, but it can also cause physical damage to the coils, necessitating costly repairs or replacements.

Strategies for Freeze Protection

1. Insulate and Protect the Installation Area: Ensure that the area around your heat pump water heater, particularly if installed in unconditioned spaces like garages or basements, is well-insulated. This can help maintain a warmer ambient temperature around the unit, reducing the risk of coil freeze.

2. Use Built-in Freeze Protection Features: Many modern heat pump water heaters come equipped with freeze protection features that automatically activate to prevent coil freezing. These may include sensors that detect when coil temperatures approach freezing points and activate defrost cycles to melt away any ice formation. Ensure these features are enabled and functioning correctly.

3. Install a Recirculation Pump: A recirculation pump can help by constantly moving water through the system, thereby reducing the likelihood of freezing. This is particularly effective in systems where the heat pump is used in conjunction with a storage tank.

4. Regular Maintenance Checks: Regularly inspect and maintain your heat pump water heater. This includes checking the refrigerant levels, as low refrigerant can cause the coils to freeze, and ensuring the defrost cycle is operating correctly. It's also crucial to check for any airflow obstructions around the unit that could exacerbate freezing issues.

5. Consider a Backup Heating Source: In extremely cold environments, integrating a backup heating source with your heat pump water heater can provide additional warmth to prevent coil freeze. This could be in the form of electrical resistance heaters or an auxiliary heat source that kicks in when temperatures drop too low.

6. Antifreeze Solutions: For geothermal heat pump systems or systems that use water-source heat pumps, consider using an antifreeze solution in the water circuit. This solution can prevent the water from freezing within the coils, provided it's compatible with your system and installed by a professional.

Long-Term Solutions and Considerations

  • System Placement: When installing a new heat pump water heater, consider placing the unit in a location that minimizes exposure to freezing temperatures. Inside placements or well-insulated outbuildings are preferable.

  • Upgrade Insulation: Evaluate and upgrade the insulation of the space housing the heat pump water heater, if possible. This could involve insulating the walls, doors, and windows of the space to create a more stable and warmer environment.

  • Professional Assessment: If you live in a region with severe winter conditions, have a professional assess your heat pump water heater setup. They can provide personalized recommendations for protecting your system against freezing, tailored to your specific climate and home layout.


Preventing the coils of your heat pump water heater from freezing is vital for ensuring the system's efficiency and longevity. By implementing protective measures, conducting regular maintenance, and utilizing built-in freeze protection features, you can safeguard your investment against the cold. Remember, proactive prevention is key to avoiding the inconvenience and expense of repairs caused by frozen coils. Should you have any concerns about your system's ability to withstand winter temperatures, consulting with a professional HVAC technician can provide peace of mind and ensure your heat pump water heater remains reliable year-round.