How to Clean a Tankless Water Heater

When we think about water heaters and cleaning them up, we automatically think about How to Clean a Tankless Water Heatertraditional water heaters with storage systems that need regular cleaning and generally attract a lot of debris and deposits. These Heaters are not as hard to maintain but they do need regular cleaning just as much as storage systems do.

The time frame for this cleaning and maintenance fluctuates depending on the type of water in your area. If the water is hard and has lots of minerals in it, more cleaning will be required but if they water is soft and the amount of mineral deposits building up in your water heater are significantly low you may not need to clean it up as often.

Tankless are generally easier to deal and the mineral deposit takes a long time to build up in them because there is no bottom of the tank that is holding up water. The system, for the most part, pushed the minerals out and given the state of technology a lot of water heaters have alert systems that update users if a maintenance is required.

Steps for Cleaning a Tankless Water Heater

  1. The first step is to shut off the power supply for your heater as well as collect the essential supplies for the clean-up. The heater can be either running on gas in which you have to shut off the gas supply and if it’s electric you should switch off the circuit breaker. You can never be too cautious. As for the cleaning supplies, you should get:
  • A bucket with holding capacity 5 gallon
  • Two washing machine hoses made of stainless steel
  • A submersible pump
  • Food grade white vinegar of quantity 4 gallons

You might have some of these items in your house, or you can purchase them. They might also be available as part of water heater cleaning kit!

  1. This step requires you to shut off the three water valves before unplugging the unit from the wall socket. Out of the three water valves, there are generic colors assigned to each for the water supply. The blue one is for cold water that flows into the system, the red one if for hot water that flows out of the system and the one for water supply to the home is yellow.

    The valves can be shut off via handles, or knobs. It is easy to turn off the knob in the opposite direction but with handles you should know the water supply is on when the handles are in line with the pipe and turned off when the handles are perpendicular to the pipe. The shape or size of the valves depend on the model and make of your heater but it’s more or less the same.

  2. For the hot and cold water supply, you will see the purge valves. You need to take off the purge port valve caps from them and this requires utmost care. The handles on these are very small so you must not do it in haste, and there may be some hot water or pressure built up beneath these caps which is why you must do it slowly or you risk spilling hot water on your hand. This safety is also necessary for the delicate caps that have rubber washer sealing discs inside them. These discs must not be displaced while you are taking off the caps.
  3. There will be hot and cold water into the valves and you need to attach the two hosing lines to the valves and then open the purge ports to drain the water into the empty bucket. The water will direct itself via the hose but the hot water will drain rather fast and you should take extra precaution while attaching the hose to the hot water. Open the hot water side slowly and check the temperature before letting it drain fully but with the cold water side no such precaution is necessary.
  4. After the water has been drained out, empty the bucket but to not detach the hoses. Use food grade white vinegar to fill up the bucket. You might be tempted to use some sort of chemical or any other type of vinegar to clean your system, but that is a dangerous choice and could end up damaging your system and/or your health. Food grade vinegar is a non-chemical formula for cleaning without any dire consequences. The ends of the hoses should be attached to the submersible pump and placed into the bucket filled with vinegar. Turn on or plug in the pump, and you will see vinegar being pumped throughout the system cleaning it up from the inside. You should let the pump run for about ¾ of an hour till an hour and a half.
  5. While the pump cleans your system you should clean the air filter. To do so, remove the face plate of the heater. Then remove the air filter, wash it up and dry it off. Once dried, replace it and then screw back the face plate.
  6. By the time vinegar has been sufficiently pumped, unplug the pump and set it aside after removing it from the bucket. Empty the bucket and place it under the water heater while removing the hose from the water side. Screw the cap back on and open the water valve to let cold water flow through the system before closing the valve and then unscrew the water filters. Rinse them and put them back in their place.
  7. Put everything back including the caps and then turn on the cold water valve. Once water starts running turn on hot water, then turn on gas and central circulation valve. Plug the system back into the wall socket and let it run.


These are the most comprehensive steps for cleaning a heater, but the specifics may change with each model. You should always refer to the manufacturer’s booklet for specific guidelines and even buy a kit if necessary. Never use chemicals as they might stay in the unit and harm you and do not use any other kind of vinegar that can stain or damage your system.