Benchmark ZWB 7-29 CC1 Installation And Servicing page 70

Failure identification procedure
Ad
flashing.
Heat store NTC sensor 1 not detected (ZB...).
Check
1. Is connecting lead for heat store
NTC sensor 1 correctly routed, i.e.
not through cable grommet?
2.
B Press button
B Select service function .3 .
Is a temperature between 0. and
5. displayed?
3. Heat store -NTC 1:
B Unplug connector from PCB con-
trol board.
B Short circuit the connector using
wire jumper.
After max. 60 sec:
Display changes to temperature
between 99. and 95.
22
yes:
no:
yes:
.
no:
yes:
no:
Action
B Note the setting of the temperature controls
and .
↓2.
B Route connecting lead for heat store tempera-
ture sensor as specified in installation instruc-
tions.
Is NTC sensor connector corroded, damaged or
dirty?
B Power OFF the appliance.
B Change NTC sensor.
B Turn ON the appliance.
B Press button
.
Ad? ↓3.
↓4.
B Power OFF the appliance.
B Change NTC sensor.
B Turn ON the appliance.
B Press button
.
↓4.
B Make a note of the altered service settings (see
table 1, "First Service Level; Values that can be
modified" at page 8 and table 5, "Secondary
Service Level; Values that can be modified" at
page 11).
B Power OFF the appliance.
B Disconnect the boiler electrical connection.
B Change PCB control board.
B Reconnect the boiler electrical connection.
B Turn ON the appliance.
B Restore service settings previously noted down.
↓4.
7 181 465 346 GB (03.02)