Tankless Freeze Protection

    Back in 2021 there was a major weather freeze event that reached far into the Southern States, places that were not accustomed to freezing temperatures experienced a prolonged deep freeze. Tankless freeze protection systems were rendered useless as widespread power outages crippled the area. In addition this wreaked havoc on plumbing within homes and businesses causing billions in damages as pipes and water heaters froze and split.

    This site saw a huge spike in traffic with people looking to prevent their tankless from freezing as well as searching for parts and replacement systems once everything had settled.

    Traffic Spike from the Southern Deep Freeze 2021

    Another spell of freezing cold temperatures is descending upon those same locations as I type this. Thus, in hopes of saving some of those newly installed or freshly repaired tankless water heaters I’m going to go though a few options of how you can stop freezing in your tankless system.

    Tankless Freeze Protection Options

    Nearly all tankless systems have freeze protection built right into them. Although each brand may utilize a different methods to prevent freezing. Some tankless systems use an electric element to provide enough heat that will prevent any internal freezing. Other brands might fire up the system heating a small amount of water and in turn keeping the interior tankless cabinet frost free.

    Both of the above freeze protection systems require an uninterrupted power supply. We all know what happened in Texas and to their electrical grid during the extreme temperatures. Unfortunately, with no electricity the built in tankless freeze protection is also removed.

    Running a generator and plugging your tankless into that will bring that freeze protection system back online. Something like a small homeowner generator will work perfectly. Alternatively you could go with a whole home generator that will kick on the moment power goes down. The last option is a battery power bank or backup. The ones that you can use to run your computer during power interruptions can also work to power your tankless. Just remember for the UPS battery backup systems, the bigger the battery system you purchase the longer your tankless will run off of it.


    Leaving The Water Running

    Leaving the water running though your tankless might work to prevent it from freezing but I certainly would only use this method if it was my very last resort. There is a lot of plumbing in a tankless and some pipes don’t always have water flowing though them when the water is just turned on. Re-circulation pumps or condensation pipes could still freeze as they wouldn’t have the constant water flow needed.

    • Turn off the tankless or use the off switch on the remote control.
    • Close the gas shut-off valve.
    • Open the hot water faucet slightly until a stream of approximately 1/8″ (.32 cm) is flowing.
    • Be sure to check the flow periodically.

    Ensure Tankless Freeze Protection Is Turned On

    As the cold air rushes down from the north and into the southern States these next few days, we can only hope that the electrical grid remains on and the freeze protection on our tankless sytems will continue to function. It would also be a good idea to check your tankless and make sure freeze protection is tuned up.


    Make sure your tankless freeze protection system is turned ON


    Rheem Tankless Freeze Protection Settings

    The Rheem water heater is equipped with a Freeze Protection Electric Heater. As long as electricity is supplied to the water heater, it prevents freezing inside the water heater down to an ambient temperature of approximately -20°F (-28°C) (without wind conditions). This device only protects the internal components of the water heater. It does NOT protect external piping and valves.


    Do not unplug the power supply cord, except for routine maintenance. The water heater has a freeze protection function that requires electricity. The freeze protection function will operate regardless of whether or not the power is turned on or off, as long as the electric supply is still connected. If the power will be off for any extended period of time. A battery back-up (available at most computer retailers) may be used to supply hot water during periods of power outages.

    Navien Freeze Protection Setting

    This menu is used to configure the circulation pump freeze protection temperature. It isn’t available on all Navien tankless systems.
    When the space heating supply temperature stays below the set value for longer than 10 seconds, the system runs the circulation pump to prevent freeze damage (the pump runs for 10 minutes, then stops for 1 minute).

    •  Default: 50°F (10°C)
    •  Setting Range: 43-50°F (6-10°C)

    Bosch Tankless Freeze Protection

    Freeze protection is always assured by the operation of the appliance. If the primary NTC (temperature) sensor detects temperatures below 41°F, the appliance starts on minimum power until the sensor reads temperatures greater than 41°F.

    • Do not disconnect the electric supply from heater.
    • Do not install in unheated areas which can experience freezing temperatures.
    • Under no circumstance use non-potable additives like glycol.

    Takagi Tankless Freeze Protection System

    Do not disconnect the electrical supply if the ambient temperature will drop below freezing. The Freeze Prevention Device only works if the unit has electrical power. The Freeze Prevention Device is rated for temperatures down to 5º F ( -15º C ) in a wind free environment.

    Takagi strongly recommends the use of its back flow prevention flue damper (Part No. TK-TV03) to reduce the amount of cold air entering through the exhaust venting when the water heater is off.

    For indoor installation in areas where the temperature will be well below freezing for extended periods of time, use the included “Extension cable” to relocate the internal thermostat located on the fan motor to the outdoors. This will sense the ambient air temperature and turn on the internal heater blocks on to prevent the heat exchanger from freezing.


    Rinnai Tankless Freeze Protection

    The freeze protection features include electrical heating elements. Freeze protection may be disabled if electricity is not supplied, or if there is an error preventing the water heater from functioning. Loss of freeze protection may result in water damage from a burst heat exchanger or water lines.

    With electrical power supplied, Rinnai water heaters will not freeze when the outside air temperature is as cold as –22ºF (-30ºC) for indoor models or is as cold as –4ºF (-20ºC) for outdoor models, when protected
    from direct wind exposure. Because of the “wind-chill” effect, any wind or circulation of the air on the unit will reduce its ability to freeze protect.

    Author: administrator

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