Worcester C1 Installation And Servicing Instructions page 35

No
Is the boiler in a very
cold environment (less
than 5°C)?
Yes
Boiler is running in
"Autofrost stat" mode.
See Section 17.
No
Is the boiler fully
water pressurised and
is all air vented?
Yes
No
Reset the controls and
restart the boiler.
Does the pump run?
Yes
Remove inner casing
cover and inspect the
No
primary sensor (left of
heat exchanger).
Is it correctly fixed to
pipe?
Yes
Remove the multiway
No
connector from board
position ST16.
Is there a short circuit
across contacts 5 & 6?
Yes
Fault caused by control
board or heat
exchanger
Replace control board.
(Section 15.4.10).
Note: A damp board
could cause this fault.
Rectify fault.
Repair or replace
pump.
(Section 15.4.18).
Re-fix sensor to pipe.
Replace overheat
thermostat or check
wiring to it
35