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Do I Need To Descale My Tankless Water Heater?

Posted: May 18, 2021

water heater descaling north carolinaThe key feature of a tankless water heater is that it’s…well, tankless, of course! Unlike a conventional water heater, it doesn’t keep any hot water on-hand ready for your taps and appliances—rather, it heats it instantly the exact moment you need it.

You might think that this means that a tankless water heater doesn’t need to be flushed periodically, since it doesn’t actually store water.

But it does!

Limescale builds up on the heat exchanger of a tankless water heater the same way it does on a conventional water heater. Even a thin layer of scale could drop your efficiency by as much as 30 percent, essentially negating the primary advantage of using a tankless vs tank system.

The good news is that descaling your tankless water heater is actually pretty easy to do. Before you try it yourself, always read the instructions the manufacturer gave you first! While the procedure detailed below is fairly standard, there might be slight but important variations based on your particular model. If you’re not comfortable tackling this procedure, don’t worry—we can take care of it for you. Just give us a call!

Here’s what you’ll need:

  • A tankless water heater flush pump
  • Rubber or washing machine hoses to attach to the valves
  • A water collecting bucket
  • Vinegar or a tankless water heater descaling solution
  • A channel lock wrench

Typical steps to descale a tankless water heater

  1. Before you begin, set your temperature to 150°F and let hot water run through the heater for about a minute.
  2. Shut off all the power to the water heater.
  3. Close the incoming and outgoing water isolation valves. If your unit doesn’t have isolation valves, then you can buy some and install them yourself.
  4. Have a bucket ready to collect water as it drains. There will be about a liter of water or so in the pipes of the tankless heater.
  5. Drain the unit and connect hoses to the drain ports of the isolation valves “A” and “B”.
  6. Dump this bucket or have another bucket ready to go with a solution to be pumped through the heater.
  7. Fill an empty bucket with a mix descaling solution and water. About a half a bucket of water will do the trick.
  8. Open the isolation valves A and B.
  9. Turn on the circulation pump. Let the solution circulate through the tankless water heater for at least 30 minutes, but an hour is better.
  10. Drain the descaling solution from the heater and flush fresh water through the heater by closing valve “B”.
  11. Open up valve “A” with a hose leading to an empty bucket.
  12. Open up the inlet water valve to let fresh water flow through the unit and empty into the empty bucket to get all of the solution out of the heat exchanger.

Descaling is not the only maintenance your water heater needs! Be sure to contact a pro a minimum of once every two years for a conventional water heater, and once a year for a tankless water heater, to keep it running at its safest and best. Contact Rand Wade Oil today to learn more about propane water heater installation and service in Greene County, NC!