How To Flush A Tankless Water Heater


    Tankless water heaters are the heaters used to heat water directly without the use of storage tanks. They are also known as instantaneous water heaters or can also be called demand-type water heaters. The water is heated by electric elements or by gas burners. This means that the water produced is very hot. When a hot water tap is turned on, the cold water gets into the pipe which is in the unit, and as a result, it gets heated.

    The manufacturers of the tankless water heaters advise the users to flush the water heaters annually. This helps to get rid of the build-ups of calcium and other minerals in the unit that may cause clogging in the unit. The tankless water heater can be flushed within an hour.

    How to Flush a Tankless Water Heater

    The following are the procedures on how to flush a tankless water heater

    Switch off the electric circuit for the heater if it uses electric elements. For those heaters that use gas to heat, rotate the gas cutoff anti-clockwise to turn it off. Ensure it is well closed to avoid gas leakage. Gas-fired water heaters normally have a higher rate of flow as compared to the electric heaters. However, the gas-fired water heaters may waste a lot of energy due to their constant high boiling point.

    Remove the cover plate from the heater so that you can get to the wirings. You might use a screwdriver to screw the bolts and keep them safely for you will return them into their respective places after the exercise. Then use the tip of a non-electrical tester to test its effectiveness in work. Place the testers against the wiring which is close to the terminals.

    In case the tester lights turn on, put them off. No wires are supposed to show access to power. Put another cover plate. Switch off the main water valve that sends water to other fixtures in the water heater. The valve that supplies cold water to the heater should also be turned off. Join together the end of the garden hose with the sump pump. This is a pump that removes the water that collects in a sump basin. Join another hose to the water isolation valve. Use an adjustable wrench to tighten up the surface.

    Put the pump and one edge of the hose in a gallon bucket and top it up with clean white vinegar. Make the vinegar run through all the surfaces from the water heater through the hoses directly to the bucket. Allow it about forty-five minutes and then close the valve. Drain off the vinegar from the bucket and put one end of the hose in a bucket. Switch on the water supply and direct the water into the bucket for around three to five minutes.

    Later switch off the cold water supply valve and the hot water valve respectively and disconnect the hoses. Follow the manufacturer's directions on how to take off the inlet filter screen of the unit. Nest, wash this screen in clean water to get rid of sediments that may have been left. Put the screen again and replace it if need be.

    After some time switch on the hot water supply valve and the cold water supply valve respectively and allow some tap water fixtures (faucets) in the house to bring air inside from the hot water lines. When enough air is accumulated, close the fixtures. This prevents wastage.

    Connect the water heater as supposed to be. For the one that uses gas, ensure a proper connection is made to prevent gas leakage. For the electric heater, ensure that the connections are good. This will prevent the wrong connection of wires as this may lead to damage to the heater. After a thorough check, feel free to turn on the gas supply valve. Equip yourself with the following equipment which will enable you to test for water at the faucets;

    • Screwdriver
    • Contact electrical tester
    • A stable wrench
    • Gallons of white vinegar
    • Sections of garden hose which have their connectors
    • Sump pump

    Before you flush the heater, ensure the power and the gas is switched off to prevent damaging the unit. Use a non-contact electrical tester before you flush to ensure that the unit power is off. Flush the system.


    The tankless water heaters provide hot water as it is needed, at the right temperatures. They help one save money in that they do not produce standby energy losses as compared to other types of heaters. A unique feature in the choose a better tankless water heater is that they heat water directly. This happens without the use of a storage tank, thus making them supply hot water constantly.

    The heaters may be of a slightly higher price than other types of heaters, but they last longer than them. Ensure there is proper installation and maintenance so that the water heater gives the best results. Also, read the manufacturers manual to know about the care and its maintenance.

    About the Author Antonio Meltzer

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