Takagi T-H3M-IN/OS - Manual (Page 42)

42
Page
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
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
A
B
C D