How To Clean A Tankless Water Heater

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A tankless water heater is a device that has heating coils placed inside it, and these heating coils heat the water while it flows through the elements. This appliance provides instant heat like rain, and nowadays, people like to use them in apartments, offices, and restaurants. This device called Tankless water heater only because it does not store any water within it except for the water, which passes through the coils while being heated. The device comes in electric, gas, or both.

Why does a Tankless Water Heater need cleaning?

A tankless water heater requires cleaning at least once every year due to mineral deposits. While the water is running through the heating coils, it brings along with it minerals that start to accumulate around the walls of the tankless water heater. If the walls are not clean so often, then the walls of the tankless water heater will start to erode causing many issues that are why it is essential to flush or in laymen terms clean the tankless water heater.

Cleaning or flushing the Tankless Water Heater

A tankless water heater is a good piece of machinery to have in your house or rental apartment but remembers that these tankless water heaters require maintenance at least once a year and it is advised to do it twice a year because they are very delicate. Below are 12 easy steps for you to use while cleaning your tankless water heater

Turn your Tankless Water Heater off at the mains

This function might seem obvious, but it is essential that you switch off your tankless water heater so that you can work unhindered and not damage the machinery. These devices are turned off at the main circuit breaker or the main gas valve depending on the make and model of your water heater.

Turn off the three water valves

Turning off these water valves is very easy.

  1. Turn off a valve that has a red handle to shut off the hot water
  2. Turn off a valve that has a blue handle to shut off the cold water
  3. Turn off the other non-coloured valve to shut the main water supply

Not only valves are colour-coded, but this is to give you a general idea. The reasons these valves are shut off is so that you do not get cold water running into the machine and so that hot water does not pour out on you.

Remove the purge valve caps slowly located under the hot and cold water valves

You need to remove the purge valve caps gradually. Make sure you do it gently not to damage the seals. The purge valves are released so the pressure is released otherwise hot water could gush out burning you.

Attach hosing lines to water valves

You must attach a hosing line to all three of the water valves. The exact procedure depends on the company and model of your water heater; for this reason, it is advised to call the company or consult a manual. If your machine did not come with a hosing line, you could purchase it from any home repair or water heater shop.

Open purge valves

This process is straightforward; you need to open the valves by turning the handle perpendicular to the hot and cold valves.

Pour white vinegar into the Tankless Water Heater

It is essential to use natural cleaning solutions like white vinegar since the tankless water heater may be the source of all your water. For this reason, using chemical solutions could harm your health. Pour around 2.5 gallons of white vinegar into the tank to clean it.

Flush and drain your tank

You must now flush and drain your tank, so it gets cleaned. For this procedure, it is again essential to consult a manual or call the company so they may guide you properly. The system can take as long as 45 minutes to complete it all depends on the specifications.

Close Purge Valves

You can go through this procedure by twisting the purge port valves back into place one the flushing is complete.

Disconnect lines

Now you must disconnect the hosing lines from each of the three water valves.

Replace the purge port caps onto water valves

Now you must place the purge port caps back into position keeping in mind to be gentle so as not to break the rubber seals within the caps.

Re-start Tankless Water Heater

For this procedure, it is essential to consult your manual for the exact method of safely re-starting your tankless water heater.

Run water

Now for the final step, you must turn the tap on and let all the air come out from the tap, so the lines become unblocked. While cleaning air gets trapped so when you turn the water heater on again, the wind tries to escape. Letting the water out helps that happen. This procedure usually takes two to three minutes.


Sometimes users place the Tankless Water Heater in such a position that all the water passes through it. For this reason, your tankless water heater should be cleaned with white vinegar as it is natural so that it won’t harm you, and secondly, it has no colouring so it won’t stain the inside of the water heater.

If the minerals inside the tankless water heater are not appropriately cleaned as calcium will solidify because of the high temperature of the heating element, when the calcium touches the heating element, it bakes it till it gets hard. A tankless water heater needs to be cleaned out at least once a year, but it is advised to clean it at least twice a year. The tankless water heater should be appropriately maintained. Otherwise, it could get damaged, and these machines are not cheap at all.

For this reason, they should be maintained by the straightforward 12 step process which will increase the life of the machine and keep it in a pristine condition.