Service Manual

Page 59
Descaling Using a Pump
▶ Disconnect the electrical supply from the water heater.
▶ Shut off the water supply to the water heater.
▶ Open hot water taps to drain and relieve pressure from the plumbing system.
▶ Shut off hot water valve to the water heater.
▶ Connect a line (A) from the outlet of the circulating pump (installer supplied) to the inlet drain
connection on the water heater.
▶ Using another line (B), connect the outlet drain connection of the water heater. Route the other end
of this line into a descaling reservoir.
▶ Using a 3rd line (C) from the descaling reservoir, connect to the inlet side of the circulating pump.
Install a filter on the end of the line in the descaling reservoir.
▶ Make sure all connections are water tight.
▶ Fill the descaling reservoir with descaling solution so both lines inside are submersed. We
recommend a straight white vinegar solution. If using a commercial descalant, refer to the
manufacturer's instructions for proper dilution ratio.
▶ Ensure both drain connections are open.
▶ Operate the circulating pump.
▶ Make sure there are no leaks and the solution is flowing from the descaling reservoir through the
heater and returning to the reservoir.
▶ Run the solution through the heater until the solution returning to the descaling reservoir comes out
clear. (Changing to a fresh solution may be necessary during this process).
▶ Disconnect all lines and drain all solution from heat exchanger. Properly discard the solution.
▶ Close the inlet drain connection.
▶ Position a container below the outlet drain connection and connect the cold-water supply. Open the
cold-water supply shutoff valve and flush the heat exchanger with clean water.
▶ Close the cold-water shutoff valve and reconnect hot water supply to the water heater.
▶ Close the outlet drain connection.
Re-assemble the heat exchanger ensuring its correct position on the two support hooks in the
appliance back plate, good conditions of seals and tightness between heat exchanger, collector and
burner.
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