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Descaling the Unit
Hard water is a severe problem for the copper coils inside heat exchangers . Heat exchanger failure due
to scale buildup from hard water conditions is NOT covered by warranty . It is highly suggested that a
scale inhibitor be installed before the cold water inlet after this procedure is done .
1) TOOLS Gather the following materials:
a . Pump: The pump should provide a minimum of 1
gpm through the heater .
b . Descaling Solution
c . Water hoses
d . Bucket
2) SETUP
a .
Set the unit to its highest temperature setting .
b . Open multiple hot water fixtures to run
a large volume of water through the water
heater . Allow the unit to run at its full
firing rate for at least 2 minutes .
c . While the water heater is still firing, disconnect
power to the water heater .
d . Shut off all the open hot water fixtures .
3) WATERLINES – Assumes isolation valves with drain
ports are installed .
a . Isolate the water heater by closing the incoming/
outgoing water isolation valves C and D .
b . Relieve pressure within the water heater by
temporarily opening up the pressure relief valve .
c . Drain the water heater and connect hoses/pump to the
drain ports of the isolation valves: Outlet of the
pump to valve B (cold side), and another hose from valve A (hot side) to the bucket .
4) PUMP and DESCALE –
a . Fill the bucket with 5 gallons of diluted solution . Dilution ratio depends on the
cleaning/descaling solution used .
b . Place the pump into the bucket if it is submersible, or use an inlet hose into the bucket if it is
not submersible .
c . Open valves A and B .
d . Circulate descaling solution through the water heater for 45 minutes .
5) CLEANSE THE SYSTEM – Flush the chemicals out of the heat exchanger with fresh water .
a . Close valve B .
b .
Open valve D and run fresh water through the water heater and drain out of Hose 2 for 15 minutes .
c . Close all valves, relieve pressure from the water heater with the pressure relief valve, and
clean the inlet water filter with fresh water .
d . Once the water heater is flushed and cleansed, replace the water filter, open C and D, and
reconnect power to the water heater .
e . Change the temperature setting back to the desired temperature .
