Gary Smith - Ridgeland MS Home Inspector

How to Maintain Your Tankless Water Heater – Annual Descale Flush

Nothing beats a nice clean cool drink of water. However, if you own a tankless water heater, you’ll want to keep the heat exchanger free of lime and scale. You should flush it annually. Here are some basic steps. The pump and hoses will cost less than $100.

HINT :: This is much easier than you think!

Water Heater Maintenance - Northtowne Builders

Basic setup for tankless water heater descale.

What you’ll need:

Follow these steps:

  • Check to see that you have a flush kit installed (see service valve in drawing at right).
  • Start by turning off the gas (if your heater is gas).
  • Make sure the unit is plugged in and is in the ON position.
  • Shut off the hot and cold water.
  • Open the caps on the flush kit. The kit looks like two hose bib hook ups with a small cap installed.
  • Set the pump into the bucket
  • Hook one of the hose from the pump to the red – inlet – side of the water heater flush kit.
  • Hook one of the hose from the heater (blue) and drop into the bucket
  • Open the drain valves on the flush kit
  • Pour vinegar into 5 gallon bucket
  • Plug-in the cord from the pump and allow to run for about an hour
  • When finished:
    • unplug the pump
    • turn off the drain valve flush kit handle
    • unhook hose and replace cap on the flush kit
    • turn the water and gas to the on position.


If you have difficulty with any step call a professional plumbing contractor or contact us for help.

Home Inspector – Home Builder and Building Consultant/Coach

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One Response to “How to Maintain Your Tankless Water Heater – Annual Descale Flush”

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