Benchmark ZWB 7-29 CC1 Installation And Servicing page 65

A7
flashing.
Hot water NTC sensor defective
Check
1.
B Press button
B Select service function .2 .
Is a temperature between 0. and
5. displayed?
2. Hot water NTC sensor:
B Unplug connector.
B Short circuit the connector.
Display changes to
temperature 99.
3. Temperature between 95. and 99. is
displayed.
B Unplug connector.
After max. 60 sec.:
Does the displayed code change
to a value between 0. and 5.?
7 181 465 346 GB (03.02)
yes:
.
no:
yes:
no:
yes:
no:
Failure identification procedure
Action
B Note the setting of the temperature controls
and .
B Flue gas connector corroded
dirty? Change relative parts.
↓2.
↓3.
B Power OFF the appliance.
B Drain the hot water circuit.
B Disconnect the boiler electrical connection.
B Change NTC sensor.
B Plug the connection wire.
B Reconnect the boiler electrical connection.
B Turn ON the appliance.
A7? ↓3.
B Change the 20-pin connector lead assembly.
↓3.
B Power OFF the appliance.
B Disconnect the boiler electrical connection.
B Change NTC sensor.
B Refill the hot water circuit.
B Check the built-in NTC sensor for leaks.
B Plug the connection wire.
B Reconnect the boiler electrical connection.
B Turn ON the appliance.
A7? ↓4.
↓4.
1)
, damaged or
17