Winterizing Tankless Water Heaters

If you have ever owned a cabin and owned a tankless water heater, you will be very familiar with draining it. Water heaters need to be drained no longer in use, and the temperatures are dropping.

Tankless water heaters are winterized to protect them from freezing. While outdoor tankless water heater units are left more exposed to changing seasonal elements, indoor systems can equally be affected. It is important to install your unit in a good location with the proper venting to prevent damage.

Winterizing Tankless Water Heaters

Winterizing Tankless Water Heaters

Winterizing tankless water heaters is done when you will not be using them for a longer duration, and the forecast calls for freezing temperatures, which is necessary for protecting the heater and plumbing.

It is important to note every tankless heater manufacturer says they shouldn’t be installed in areas where temperatures 36° F or lower. If you do not perform winterization on the system (like draining it), the unit may become damaged. The warranty will not cover this type of negligence.

Related: Rheem Water Heater – Ultimate Troubleshooting Guide

These steps will prevent the system from failing:

  1. The power cord should be unplugged, and the heater turned off. To turn the gas off, use the main valve located on the gas supply line. In terms of electrical, unplug your cord or shut the power off on the breaker. The display (if you have one) should be black without lights.
  2. Hot water may still be inside the system. If it was on and before draining, wait until the hot water completely cools.
  3. Use the main shut-off valve to turn off the water supply.
  4. Open taps to allow the water heated tank to drain. It will release pressure from your plumbing.
  5. Once water pressure decreases, the inlet and outlet water pipes need to be disconnected.
  6. Take out the inlet water filter.
  7. Place a bucket underneath to collect excess water. Any remaining water can be removed with an air compressor if needed.
  8. Cover the vent termination on both the intake and exhaust to prevent debris from entering.
  9. If your system has drain plugs, then remove them. They can be found at the bottom of your unit.
  10. Now your water heater is completely winterized.

Protection From Freezing

Modern tankless water heaters usually have a mechanism for freeze prevention. This only works during the winter months. It is not designed for areas where freezing temperatures remain this way for prolonged periods.

It only protects the heater- not exterior plumbing. A freeze prevention heater always needs to be connected to an electrical outlet. It runs on an automated system and will turn off/on whenever it needs to.

Rinnai tankless water heaters contain protection from cold temperatures. They have ceramic heaters placed on the heat exchanger. They come on when temperatures plummet into the low 30s and keep the internal components from freezing.

If the ceramic heaters don’t work or the temperature decreases too quickly for the until, secondary protection from freezing kicks in. A sensor is located inside the system and determines if it is below freezing. Once triggered, the unit is turned on for several seconds and will cycle the heater off/on until the threat has dissipated.

Homeowners should protect external pipes from the cold, too. To do so, wrap them with a pipe heating cable or pipe wrap insulation. Both of these will prevent your pipes from freezing during the winter months. Both solutions are inexpensive, easy, and quickly available.

These methods prevent pipes from freezing in temperatures rated up to -50° F. Some homeowners use both methods. However, check with the manufacturer before proceeding.

Thawing A Frozen Tankless Water Heater

Freezing temperatures are known to cause pipes and water heaters to freeze. If freezing has occurred from the external piping to the water heater or the system alone, do not turn the unit on.

Instead, follow these instructions:

  1. Close the shutoff valves to the gas and water. Turn off the electricity.
  2. Wait for the tankless water heater to completely thaw. To see if it has thawed, open your water supply valve. If you see water, the heater has thawed.
  3. Examine the internal components, external pipes, and plumbing to ensure there are no leaks.
  4. If everything is fine, open water and gas valves. Turn the power on.
Freeze Water Pipe

Things to Consider

Whether it is a concentric system or dual vent, keep the vent pipes facing away from the wind. Protect the condensation drain tubing from being exposed to extreme cold. Experts recommend creating a wall to shield it from the weather.

A negative draft happens when furnaces draw in air from vent pipes, causing cold air to enter the system. The water then becomes frozen in the heat exchanger. Therefore, all gas-powered heaters need sufficient air. You can install a backdraft reducer that closes the internal flapper to prevent this from happening.

If temperatures drop, protect the tankless heater by opening the hot water tap. Have a small stream of water going. Before doing this, the gas supply valve needs to be turned off and shut off the power to protect both the heater and piping.

In the event of a power outage, drain the water heater to prevent any damage. Avoid using antifreeze fluids because they can ruin internal components. Doing this can put the heater at risk and can additionally void the warranty.

Winterizing a tankless water tank is simple. When temperatures drop and you are not using the unit, you must winterize it before leaving if it is in a cabin or any location that is not constantly in use.

Even for year-round usage, make sure the system is protected against harsh winter climates. There are individuals in the extreme northern and southern climates that use tankless systems. These units require special care as well.

To ensure you have the best system for your climate and use, check with a trained professional. They will make sure that you have the best product for your needs and location.

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