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How to winterize a Tankless Water Heater
How to winterize a Tankless Water Heater
Updated over a week ago

IIf you have a tankless water heater that is not used for a longer period and your area experiences freezing temperatures, it's crucial to protect the unit during winter. Follow this step-by-step guide to winterize your tankless water heater and prevent damage.

Why Winterize Your Tankless Water Heater?

Many modern tankless water heaters, like those from Rheem, AO Smith, Rinnai, and Paloma, feature advanced technology that protects against freezing temperatures, sometimes as low as -30°F. However, these systems rely on electric power. If there is a power outage, the unit can fail. Therefore, it's essential to winterize your tankless water heater manually during cold weather.

Important Note: Most manufacturers specify that tankless heaters should not be installed in areas where temperatures can drop to 36°F or lower. Failure to take precautions, such as draining the unit, can void the warranty. Adding antifreeze solutions is not recommended as it can damage the heater's components.

This is particularly important if your tankless water heater is installed in locations like cabins or garages, or if you will be absent for an extended period.

Step-by-Step Guide to Winterizing

  1. Turn Off Power and Gas:

    • Turn off the gas supply using the main valve on the gas line.

    • Unplug the power supply cord to turn off the electricity. If your unit has a display, it should be black.

  2. Cool Down the Unit:

    • If the heater was in use, wait until the water cools down.

  3. Shut Off Water Supply:

    • Turn off the main water shut-off valve.

  4. Open Taps:

    • Open the taps to drain the system and release pressure from the plumbing system.

  5. Disconnect Water Pipes:

    • Disconnect the incoming and outgoing water pipes from the tankless heater.

  6. Remove Inlet Water Filter:

    • Take out the inlet water filter.

  7. Drain Residual Water:

    • Use a bucket to collect the residual water, ensuring it fully drains from the system.

  8. Optional Step:

    • Some manufacturers recommend using an air compressor to blow short bursts of air through the inlet connection to ensure no water remains inside the heater.

After completing these steps, your tankless water heater will be fully winterized and protected from freezing temperatures.

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