Descaling the unit, Normal operation owner's guide – Takagi T-H3M-IN/OS User Manual

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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 – Assuming 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 or until return water is

cleared

5) CLEANSE THE SYSTEM – Flush the chemicals out of the heat exchanger with fresh water

a Close valve 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

Normal Operation

Owner's Guide

Isolation Valve

Water

Heater

H C

Gas Supply

Isolation

Valve

Pressure Relief

Valve

Hose 1

Pump

Inlet Hose

(may or may not be needed,

depending on type of pump)

Hose 2

Descaling Solution