Caring For Your Tankless Water Heater

Caring for your tankless water heater involves both preventative measures and annual maintenance  A properly installed and maintained tankless water heater can provide hot water for up to 25 years. 

Hard Water

The most common enemy of a tankless water heater is hard water, which contains a high mineral concentration of calcium and magnesium ions. These deposits will cause hard scaly buildup on the heating units (like the white buildup you may see on other faucets).

Over time, the scaly buildup can cause the heat exchanger within the tankless heater to overheat, sending an error code to lock out the system.  When this happens, your access to heated water may be totally cut off until the problem is fixed. Avoid wasting the time and money to fix this by taking preventative steps.

  • Attach a whole-house water softener system to your water source. This will decrease the level of lime/calcium buildup not just in the heater, but in the pipes of your dishwasher, washing machine, sinks, etc. Your water will also feel softer or smoother.
  • Flush your heater once every 6 months to a year. While it may be easier to hire a professional,  you can save up to $200 by doing it yourself.

How to Flush Your Tankless Water Heater

  1. Remove the cover plate exposing the power source (gas or electric) and shut off valves and water source connections. Refer to your owner's manual for identification.
  2. Shut off all lines and water inlet and outlet sources. You may have a system containing two sources of power—one for the heating element, the other for the control panel. Be sure to turn off both.
  3. Release all water pressure by opening the overflow valve (refer to owner's manual to identify).
  4. Place a sump pump of 1/6th horsepower in a 5 gallon bucket. Connect a small hose to the OUTPUT connection of the sump pump, and connect the other end to the INPUT connection on the tankless heater.
  5. Connect another small hose to the OUTPUT side of the heater. Let the other end rest open in the 5 gallon bucket.
  6. Add 2 to 3 gallons of white vinegar and one gallon of water to the sump pump bucket. Make sure the pump is submerged in the vinegar/water mix and that the OUTPUT heater hose will run back into the bucket.
  7. Start the pump and allow the vinegar to cycle through for 45 minutes.  This process will remove the lime and calcium, freeing up your system to run like new again.