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Winterizing For Seasonal Use; Mineral Scale Build-Up - Bosch Greentherm 9800 SE 160/199 Manual

Indoor residential and comme rcial tankless water heaters
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solution. Scale build up will shorten the life of the water
heater and damage resulting from scale is not covered
under warranty. Refer to section7.3 for detailed
instructions on descaling the heat exchanger.
Fin Coils
Inspect the heat exchanger fin coils for soot build-up or
blockage. To access the fin coils, consult for details. If there is
evidence of soot build-up or blockage, the heat exchanger
should be removed by a professional and cleaned
thoroughly. Soot is in indication of incomplete combustion
and a clear sign of a serious problem. Venting, gas pressure
and flue gases should be examined to determine the cause
of the problem. Damage to the water heater caused by
incorrect installation or adjustment are not covered by the
manufacturer's warranty.
Condensate Siphon
Check for debris and clean if needed.

Winterizing for seasonal use

The water heater must not be installed in a location where it
may be exposed to freezing temperatures. If the heater must be
left in a space which is likely to experience freezing
temperatures, all water must be drained from the heater.
NOTE: Use of agents such as anti-freeze is not permitted and
voids the warranty, as they may cause damage to the water
heater's internal components.
1. Press ON/OFF switch on the water heater to turn OFF the
heater and unplug the power supply cord. The display
should be blank.
2. Shut off the gas supply to the water heater.
3. Shut off the water supply to the water heater using installer
supplied shutoff valve.
4. Open hot water taps to drain and relieve pressure from the
plumbing system. If water continues to flow after 5
minutes, a crossover of the hot and cold water pipes is
present and must be corrected before proceeding.
5. Disconnect the inlet and outlet water pipes from the water
heater. Place a small bucket underneath the water heater
to catch residual water remaining inside the water heater.
6. Using an air compressor, blow short bursts of air (100psi
max) through the inlet water connection or inlet water filter
until there is no water present coming through the outlet
water connection of the heater.
7. Empty condensate trap.
8. Reconnect the water fittings and return the heater to
service when danger of freezing has passed.
Greentherm 9800 SE 160/199 | SEC 199

Mineral scale build-up

Periodic descaling may be necessary in areas with high mineral
content in the water. Scale buildup in the heat exchanger may
result in lower flow rates, error codes of A1 and A5 and boiling
sounds in the heat exchanger.
A water softener is required if the water hardness exceeds 6
grains/gal (180 mg/l) calcium carbonate. Damage to the water
heater resulting from hard water/scale deposits will not be
covered under warranty.
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 (see fig. 46.)
▶ Using another line (B), connect the outlet drain connection
on 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 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 manufacturer's instructions for proper dilution
▶ 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
▶ 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
▶ Close the cold water shutoff valve and reconnect hot water
supply to the water heater.
▶ Close the outlet drain connection.
Maintenance and service | 47
6 720 816 815 (2016/10)



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