A traditional water heater stores hot water, providing a natural buffer against freezing temperatures. However, tankless water heaters, which only heat water when needed, are more vulnerable to freezing in colder conditions. If your tankless water heater freezes, not only can it disrupt your hot water supply, but it may also damage the unit. Fortunately, with the help our expert Joseph we prepared right steps, through which you can prevent freezing or safely thaw a frozen unit.
Why Do Tankless Water Heaters Freeze?
Tankless water heaters are designed to be compact and efficient. However, because they don’t hold a reserve of hot water, they rely on external factors like location and weather conditions to avoid freezing. Outdoor units are especially susceptible to freezing, particularly during power outages or extreme cold snaps.
Most modern tankless heaters have built-in freeze protection mechanisms, such as heating elements or sensors that activate at low temperatures. While these features provide some protection, they may not be enough during prolonged power outages or in locations with harsh winter conditions.
Preventing a Tankless Water Heater from Freezing
By following a few preventive measures, you can significantly reduce the chances of your tankless water heater freezing during cold weather. Let’s go over these steps in detail.
1. Install in a Sheltered, Insulated Area
One of the easiest ways to protect your tankless water heater is by installing it in a location shielded from direct wind exposure and harsh elements. If possible, place the unit in a garage or basement where temperatures remain more stable. For outdoor installations, consider using a tankless water heater cover specifically designed to shield it from cold air, snow, and ice. In Colorado, they build insulated boxes around tankless water heaters that are outside.
2. Run a Faucet on Low During Cold Spells
Water is more likely to freeze when it’s stagnant. To avoid freezing, run a nearby faucet at a low trickle during freezing temperatures. A flow rate of about 0.2 gallons per minute is typically enough to keep water moving through the system and prevent freezing. If water conservation is a concern, you can collect the dripping water and reuse it around the house.
3. Connect to a Backup Power Source
Since many tankless water heaters rely on electrical components for freeze protection, a power outage can leave your unit vulnerable. To prepare for this, connect your tankless water heater to a generator or compatible battery powered inverter. This will ensure the internal heating elements remain powered during outages, especially during extreme cold. A portable generator can be a cost-effective backup if you don’t have a whole-house system.
4. Install a Solenoid Valve for Automatic Draining
A solenoid valve is an excellent fail-safe for protecting your tankless water heater during power outages. This valve automatically opens when there is no electricity, allowing the water inside the unit to drain out. By emptying the water, the system reduces the risk of freezing, even if external temperatures drop. When the power returns, the valve will close, allowing the unit to function normally again.
5. Manually Drain the System for Winterization
If you know the temperature will drop significantly or you’re leaving your home for an extended period, it’s wise to winterize your tankless water heater by completely draining water from the water heater. Here’s how:
- Shut off the cold water supply, gas supply, and temperature control.
- Turn off the circuit breaker to the unit.
- Open a hot water tap to relieve pressure and then open the drain caps and isolation valves.
- Remove any inline filters and place a bucket underneath to collect residual water.
- Cover the vent intake and exhaust to block cold air and debris from entering the system.
By draining the system, you eliminate the chance of water freezing inside the unit and causing damage.
6. Insulate the Pipes
Even if your water heater is equipped with freeze protection, the pipes connected to it can still freeze and cause damage. Wrapping the pipes in foam insulation or using electric heat tape can help prevent freezing. These materials act as a barrier, blocking the cold air from reaching the water inside.
Important Tip: Avoid Overheating Your Water Heater
While it may seem logical to increase the temperature setting to combat freezing, this can cause more harm than good. If ice forms inside the water heater, the heating elements can overheat, leading to potential fires or damage to the unit. It’s best to stick with the recommended temperature settings and rely on preventive measures.
How to Thaw a Frozen Tankless Water Heater
If your tankless water heater has already frozen, avoid turning it on. Attempting to run a frozen system can lead to severe damage, including cracked pipes or even internal components overheating.
1. Assess the Situation
Before attempting to thaw the heater, check whether the problem is limited to the unit or if the surrounding pipes are also frozen. If the pipes appear damaged or burst, call a plumber immediately. Thawing a frozen system with damaged pipes can cause flooding.
2. Turn Off the Power and Gas Supply
Once you’ve ensured the pipes are intact, turn off the power to the unit to prevent any electrical malfunctions. Additionally, turn off the gas and water supply to avoid any mishaps during the thawing process.
3. Move the Unit to a Warmer Area
If possible, relocate the tankless water heater to a warmer indoor space. This allows the ice to thaw gradually without applying excessive heat. If moving the unit isn’t feasible, use a space heater or hair dryer to gently warm the exterior. Never use direct heat sources like torches, as they can cause damage to wires and parts by also causing a fire hazard.
4. Open the Drain Valve
As the ice inside the unit begins to thaw, open the drain valve to allow water to escape. This prevents pressure from building up inside the heater and reduces the risk of leaks or further damage.
5. Inspect for Leaks
After the water heater has fully thawed, check for any leaks in the pipes or the heater itself. If everything looks intact, you can proceed with reinstalling the unit.
6. Restore Power and Test the Unit
Once you’re confident there are no leaks or damage, reconnect the gas and water supply, restore power, and test the unit. Ensure it’s functioning properly by running hot water through the system and checking for any irregularities.
Conclusion
A tankless water heater is an efficient and space-saving solution for your hot water needs, but it requires extra care during winter and cold weathers to prevent freezing. By following these steps—such as installing the unit in a sheltered location, using backup power, and insulating pipes—you can ensure your tankless water heater remains in top condition throughout the winter. If it does freeze, taking swift and careful action to thaw it out will minimize the risk of damage and ensure a quick return to normal operation.
