How to clean a boiler

Written by eliah sekirin
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How to clean a boiler
(Comstock/Comstock/Getty Images)

Residential boilers come in different shapes and sizes. The most popular design is a gas boiler that heats water to provide the heating and hot tap water for the house. Boilers typically do not require cleaning very often and a thorough cleaning before the installation is enough to keep the boiler clean for years or even decades. However, as time goes by, visible scale begins to form on the outside of the valves, pipes or fittings. It is time to clean your boiler.

Skill level:

Things you need

  • Boiler cleaning and descaling chemical treatment
  • Clean water

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  1. 1

    Use 1 pound hydrochloric or sulphamic acid-based cleaner and a descaler per 50 gallons of water. You might be able to purchase the proper chemicals from the manufacturer of the boiler, or from the hydro utility company that services your boiler.

  2. 2

    Dissolve one pound of cleaner in every gallon of water. Then pour the treated water in the air space of the boiler's expansion tank.

  3. 3

    Let the system fill. Vent the air from the boiler's expansion tank by the way of opening its manual bleeder valve. Then set the temperature at about 71.1 to 79.4 degrees Celsius. Let it run filled with cleaning solution for two to four hours.

  4. 4

    Open the drain valve of your boiler to let all of the cleaning solution drain out. Flush the boiler with lots of clean water by opening the manual water feed valve, remove all of the solution from the boiler and the hydro system.

  5. 5

    Fill the boiler with clean water once again, vent it and then set it to about 65.6 degrees Celsius. Let it run for 30 minutes to one hour.

  6. 6

    Drain the water one more time, flushing the system once more. Flush and drain it till the water comes out clear.

  7. 7

    Refill the boiler with water, venting the excess air. Now set your boiler to resume normal operation.

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