How to flush Rheem tankless water heater

by Zee from water heater reviews

Step by step guide, how to flush Rheem tankless water heater.

Flushing a tankless water heater is as important as flushing the tank-type unit. This is especially important if you live in the area with the hard water conditions.

Lime and scale build-up inside your Rheem tankless water heater will happened anyhow so the best is to protect the system by flushing it regularly.

The most critical element in any tankless water heater is heat exchanger, where the heat from the burning gas is transferred to the water. If the sediment are obstructing the normal water flow you will have the low performance of your tankless unit.

This is what the flushing process covers:

  • Always turn the electrical power, gas supply and water supply off on your tankless water heater before you start flushing the system.

  • Use two garden hoses and attach on the drain valves. Connect one side of the first garden hose to the cold water supply on your tankless unit and the other side to the circulating pump. From the pump hose goes into the bucket. With the other garden hose connect the hot water valve on the unit and put the other side to the bucket.

  • Pour approximately five gallons of food grade white vinegar into the bucket.

  • Open the drain valves and turn the pump on. Let the pump run for approximately one hour.

  • Turn the circulating pump off and drain the vinegar from your Rheem tankless unit.

  • Open the main water valve and allow cold water to flush the system for several minutes.

  • As your Rheem tankless water heater has the inlet water filter to protect the system from the dirt, remove it and clean the sediments. Before you clean the filter don't forget to turn the main water valve off.

  • Put the water filter back, open the water valves and purge the air from the system by opening the hot water tap.

  • Check for leaks.

  • Turn the gas and electricity on and run the Rheem water heater.

  • By flushing your Rheem tankless water heater you will definitely get improved performance and efficiency and you will prolong the life of your heat exchanger.

    Comments for How to flush Rheem tankless water heater

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    Nov 28, 2016
    by: Kevin

    Started flushing only dribble comes out ; pump is working fine ; took filter out runs much faster

    Jul 26, 2011
    clearing codes
    by: Anonymous

    according to their site, unplug, wait a few minutes plug back in should clear code

    Nov 21, 2010
    Tankess flush and codes
    by: Streetman plumber

    I flushed the tankless heater as prescribed, however, the IL code does not clear. Upon flushing with water there was some sediment that was noted, however, not much lime or calcium build up was present or witnessed during the one hour vinegar flush. Does the code clear automatically or is there a process to clear the code?

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