Hamworthy Wessex 100 M100 Installation, Commissioning And Servicing Instructions page 28

Figure 12.2b Fault Finding Procedures (Cont.)
Continued from
Fig 12.2a
Does the gas valve operate,
lighting the burner ?
Yes
Does the boiler operate at
High fire ?
Yes
Does the boiler
operate at Low fire ?
Yes
The boiler is operating
correctly.
HAMWORTHY HEATING LTD
No
Is there power at the
gas valve ?
Yes
Replace the gas valve
No
Is the High/Low link across
terminals (C3 - C4) ?
Is the flame signal from the
probe above the minimum
(0.7uA) ?
Yes
Is there power at the gas
valve High fire solenoid ?
Yes
Does the damper blade
move to the High fire
Yes
Replace the gas valve
Check setting of High/Low
No
thermostats. Check damper
operation.
Does the boiler cycle
On/Off rapidly ?
No
Does the boiler overheat
and the system remain
No
Boiler noisey
WESSEX 100 M
No
No
Yes
No
No
No
Yes
Yes
Yes
22
Check the gas valve
plug and wiring
Check C3 & C4 terminal
wiring. Check B.E.M.S
load requirements
Check the probe wiring
Check gas valve plug and
wiring. Check pressure
switches. Check timer
delay relay on pcb.
Check that the damper
blade is free. Check
solenoid coil
Thermostat faulty. Poor
circulation due to air in
system or faulty pump
Poor circulation due to air
in system or faulty pump
Poor circulation. Thermostat
set too high or faulty. Boiler
waterways scaled up. Gas
pressure incorrect. Check
gas setting pressure
500001080/F