Winterizing For Seasonal Use - Bosch 940 ES Installation Manual

shutoff and supplied water shutoffs, carefully remove
inlet and outlet clips on watervalve. Remove water
valve to access filter. Clean or replace if damaged.
Descaling
• In areas where the water supply has a high mineral
content (see Table 22, page 29), the heat exchanger
should be periodically flushed with a descaling
solution. Scale build up will shorten the life of the
water heater and damage resulting from scale is not
covered under warranty. Refer to section 6.3 for
detailed instructions
exchanger.
Fin coils
• Inspect heat exchanger fincoil for soot build-up or
blockage. To access fincoil, venting must be
removed from flue gas exhaust accessory. With
venting removed and inspect fincoil below with a
flashlight. If there is evidence of soot build-up or
blockage, the heat exchanger should be removed by
a professsional and cleaned thoroughly. To remove
the heat exchanger, consult service bulletin at
www.bosch-climate.us.
6.2

Winterizing for seasonal use

Installation instructions state that 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
temperatures, all water must be drained from the heater.
If precautions are not taken, resulting damage will not
be covered under the warranty. NOTE: Use of agents
such as anti-freeze is not permitted 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 power supply cord. The
display should be blank.
2. Shut off gas supply to heater.
3. Shut off the water supply to the water heater using
installer supplied shutoff valve.
4. Open hot water taps to drain the plumbing system. If
water continues to flow after 5 minutes, a plumbing
crossover is present and must be corrected before
proceeding.
5. Open service valves (if available) or disconnect 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 outlet water connection
until there is no water present coming through the
inlet water connection of the heater.
7. Reconnect water fittings and return heater to service
when danger of freezing has passed.
6 720 644 930
on descaling the heat
to experience freezing
6.3 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
A7 and E9 and boiling sounds (knocking and banging)
in the heat exchanger.
Descaling using a pump
1. Disconnect electrical supply from the water heater.
2. Shut off the water supply to the water heater using
(installer supplied) shutoff valve.
3. Open hot water taps to drain and relieve pressure
from the plumbing system.
4. Drain water from the unit's heat exchanger by
disconnecting inlet and outlet water connections
from the heater.
5. Connect a line (A) from the outlet of the circulating
pump (installer supplied) to the inlet water fitting on
the water heater (see Fig. 64).
6. Using another line (B), connect to the water outlet
fitting on the water heater. Route the other end of this
line into a descaling reservoir.
7. Using a 3rd line (C) from the descaling reservoir,
connect to the inlet side of circulating pump. Install a
filter on the end of this line in the descaling reservoir.
8. Make sure all connections are "water tight.".
9. Fill tank with descaling solution so both lines inside
are submersed. We recommend straight white
vinegar. If using a commercial descalant, refer to
manufacturer's instructions on dilution with water.
10.Operate the circulating pump.
11.Make sure there are no leaks and the solution is
flowing from the descaling reservoir through the
heater and returning to the reservoir.
12.Run 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).
13.Disconnect all lines and drain all solution from heat
exchanger. Properly discard of solution.
14.Position a container below the hot water outlet and
connect cold water supply. Open cold water supply
isolation valve and flush heat exchanger with clean
water.
15.Shut cold water shutoff valve and reconnect hot
water supply to the water heater.
Maintenance and service
39