Tankless maintenance in Ontario call. (647) 931-5211

Why You Need to Flush Your Tankless Water Heater

All water based appliances have troubles with limescale build-up, even traditional water heaters but tankless water heaters are particularly a concern. A tankless water heater is a very expensive and finely tuned system. If the unit isn't flushed, it can result in serious issues.

Limescale build-up occurs when the minerals within the water separate out and begins to form a film within pipes, heat exchangers and anywhere else the water travels. When a tankless unit is flushed, the limescale is flushed from within the unit. 

Most manufacturers recommend flushing every 12 months, however, you should make the decision based on your location. Some areas
are prone to harder water than others, which will create more limescale. The ​higher the mineral content within the water, the more lime scale will build within the unit.


Why flushing is so important:
  • ​Lime scale build-up can wreak havoc on the internal parts of your tankless system and ultimately cause expensive damage. 
  • The heat exchanger is extremely sensitive to lime scale. Even a small amount of build-up will lower the unit's efficiency and increase your fuel costs.
  • As the lime scale build-up increases the heat exchanger's burner cycles also increase to compensate for the loss of efficiency. The unit works harder than needed and the lifespan is shortened.
  • Most manufacturer warranties do not cover damage caused by water quality. This includes lime scale build-up.

The cost of flushing your tankless water heater can be as low as buying 4-gallons of vinegar. There are some supply's you'll need, but once you have them you'll be set for the future. 

Isolation Valves with Service Ports

Isolation valves with service ports are an optional item. Some manufacturers include them with their tankless system, while others leave the decision to the plumber and homeowner.

If your tankless system doesn't have isolation valves with service ports, we strongly recommend having them installed by a plumber. They will make the flushing procedure much easier. ​


These isolation valves with ports come with a hot water pressure relief valve. The yellow handles are the cold and hot water shut-offs, and the red and blue handles open and close the hot and cold water service ports.


Most manufacturers recommend using vinegar, however there are some commercial solutions available. Vinegar is environmentally friendly, safe, inexpensive and effective. 

** There is a flush kit available that contains hoses, a pump & a bucket.