Mineral Scale Build-Up; Troubleshooting; Introduction; Burner Does Not Ignite When A Hot Water Faucet Is Opened - Bosch Greentherm 9800 SE 160 Installation And Operating Instructions Manual

48 | Troubleshooting

7.3

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 AA, E3,E5 and boiling
sounds in the heat exchanger.
A water softener is required if the water hardness exceeds 14
grains/gal (200 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. 51.)
▶ 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
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.
6 720 816 815 (2017/06)
▶ Reconnect the electrical supply to the unit, open the water
shutoff valves, and return the unit to service.
Fig. 51
[1] Pump
[2] Water filter
8 Troubleshooting
CAUTION:
▶ If you are unable to perform the tasks
listed below, or need additional
assistance please contact a service
provider or contractor.
8.1

Introduction

Many of the questions customers ask regarding operation of
this unit can be answered by following the troubleshooting
steps as outlined below. For best results, perform each step
before proceeding to the next. The suggested solutions may
require that the cover be taken off (see fig. 3, page 10).
8.2 Burner does not ignite when a hot water
faucet is opened
It is recommended to use "P4 Information" page 40, chapter
6.5.1 as a tool for problem solving.
1. If the display is blank, verify power at the outlet. (120VAC/
60Hz properly grounded circuit required). Confirm power
to the heater.
Greentherm 9800 SE 160/199 | SEC 199