A Guide on How to Descale Tankless Water Heater

Scale, or calcium and lime build-up, accumulates on anything that utilizes water, including your tankless water heater. It requires frequent descaling to operate effectively. However, a tankless water heater is a little more difficult to flush and descale than a tank water heater.

Step To Descale Tankless Water Heater

Hire a qualified plumber to assist you in accessing the tankless water heater. Since tankless water heaters are built into the walls of your house, detaching and reconnecting them for the descaling procedure can be challenging and are best left to an expert.

how to descale tankless water heater

You’ll need the following to descale a tankless water heater:

  • A 5-gallon bucket
  • 3 to 4 gallons of distilled, food-grade white vinegar
  • 2, ¾ inch connection drain hoses
  • A submersible pump

How to Descale Tankless Water Heater

  1. Turn off the gas valve while leaving the appliance on.
  2. Separately open the cold and hot valves. The drain covers on both valves must be taken off. You should set a five-gallon bucket underneath the hot water side. Use the bucket to drain the unit of any extra water that may still be inside after carefully turning the red drain valve to the “on” position.
  3. On the side of the cold water, repeat Step two.
  4. Place the five-gallon bucket with the submersible pump inside after hosing it up. Ensure that the power cable is kept away from the bucket.
  5. The cold water drain valve should be connected to the pump output line.
  6. Put the end of a drain line into a bucket and attach it to the hot water drain valve.
  7. Put enough vinegar in the bucket to thoroughly cover the pump. Turn on the pump for at least an hour after opening both drain valve lever handles on the isolation valves. After 30 minutes, replace the vinegar solution and repeat for optimal impact. Due to the gas being off, the unit will attempt to start but fail. Eventually, which is typical during the operation, an error code 11 will show up. NEVER RESET.
  8. Turn off the pump and close the cold water drain valve after at least one hour. Replace the cover on the drain valve outlet after removing the hose from the cold water drain valve.
  9. Drain the liquid after removing the pump and drain the hose from the bucket. Open the cold water main valve and re-insert the hot water drain hose into the empty bucket. Cleansing the heater thoroughly will be possible with the help of this technique. Until 20 gallons of water have flowed through the heater, flush for at least five minutes.
  10. The next step is to drain off any descaling solution that may have accumulated in condensing units, set a bucket underneath the unit, and screw open the drain cock next to the water heater. Change the primary inflow valve’s setting to “OFF.”
  11. Remove the water filter for cleaning and other tankless water heater cleaning solution—some water may leak out. To clear the filter of any particles, run water through it. Reinstall the dry filter into the port, ensuring to hand-twist it shut.
  12. Activate the “OFF” position on the drain valve. Remove the drain pipe by unscrewing it. Make sure the drain cap is properly put on before replacing it.
  13. Restart the gas supply after turning the main hot and cold valves back to the “ON” position. Descaling caused error number 11. Thus to remove it, reset the device by turning it off and back on.

How Often To Descale Tankless Water Heater

Your tankless water heater should normally be cleaned once a year to preserve efficiency.

However, the hardness of your water is a factor, so if the water in your home is really bad, you could find it preferable to flush twice or thrice a year. A sediment trap or softener can help with hard water to some extent.

Bottom Line

Now you’ve understood how to descale tankless water heater. A regular tankless water heater flush should be performed as part of routine maintenance at least once per year.

If the region is dusty, you might need to take care of additional responsibilities more frequently, such as cleaning the unit’s exterior. It can also be smart to install a sump pump to safeguard your basement equipment.

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Heater Technician is a skilled author and water heater expert with years of experience in the field. He has authored several articles and books on various aspects of water heater installation, maintenance, and repair.