How to Flush Tankless Water Heater?

Regular cleaning of the tankless water heater is essential to prevent damage from minerals stored in it. It’s recommended to descale a tankless water heater once a year which is good for its efficiency.

Both gas & electricity drives water heaters. The only difference is if you have a gas fuelled unit, then you need to turn off the gas valve & for the electric heater, you need to turn off electricity from the socket.

We will describe to you how to flush a Rinnai tankless water heater as a reference machine. Generally, this flushing process is common but sometimes can vary slightly as per the manufacturer’s requirement. Please prepare the below materials-

  1. Three gallons of white vinegar
  2. A submersible pump
  3. A 5 gallons bucket
  4. 2 hoses

How to Flush Tankless Water Heater?

Please check if you have flush kits installed in your unit. There should be two valves in it. Through the blue color one, cold water passes to the heater inside & through the red color one, the water goes into the house.

  • The first step is you need to turn off the gas line valve. Just set the valve perpendicular to the gas line. It’s turned off. Since the power is on, such electricity is still running to the unit.
  • Set the blue color water valve perpendicular to the line & the red color hot water valve also perpendicular to the front. These actions make both valves turned off. So the main water gates are locked to pass inside the unit.
  • Open the caps from the blue & red valve. Now open the cold water draining blue lid to remove the water from the pipe. Open the hot water draining red valve to remove the water stored inside. Open up the pre-filter by a tool. Clean the pre-filter by just sinking it in a bucket & reset it to its place.
  • Pour three gallons of vinegar into the bucket. Put the sump pump at the bottom of the bucket. Set the hosepipe end at the blue color cold water drain valve. Get the other hosepipe. Lock one end to red color hot water drain valve & put another term into the bucket so that the vinegar can come out through this end & recycle the flushing process by the pump. You can use a wrench to tighten the hosepipe end.
  • Plugin the pump & flushing the water heater with vinegar will be started. This process should be continued minimum of 1 hour to clean the junk thoroughly.
  • After descaling your Tankless water heater, you need to reset the unit to make it usable again. Turn off the pump. Close blue color cold water drain valve & put the cap on it like the previous setting.
  • Open the cold water main valve & let the fresh cold water flush inside so that all the vinegar & descaled junk is washed out from the unit. Maintain this process for 10 minutes.
  • Remove hose pipes & put a cap on both flushing valves. Open the cold & hot water valves, turn on the main gas line valve. Check at your shower that your water heater is functioning correctly or not.

So it would help if you flushed to descale your tankless heater once a year.

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