Potterton Suprima 120 lockout

[louthman]

Gas Boiler: Potterton Suprima 120
Age of boiler 3 years approx.
Problem existed since I bought house 2 years ago.

Problem: Lockout

Symptoms:
Radiators boiling hot, reducing temperature control has no effect.
Inspected temperature sensor, (part number 8404516) seems it
cannot be clipped securely to pipe.

After lockout, very difficult to make a reset, usually involved turning power off, for 5 minutes, turn power on, and hope reset works, other times requires a thump on the control panel.
(to me, this indicates loose wiring or PCB connection)

Already had it serviced (140 bleedin quid), only difference now is, the
flame burns a wee bit cleaner, Only Words of wisdom from serviceman was, these Potterton boilers are useless, should have got yourself a German made boiler, mate !

I have a new temperature sensor ordered, but they don't have any "conducting paste"

Questions:
1) should the temperature sensor click into the pipe ?
2) if I replace the sensor, is it ok, if I skip the applying conducting paste ?
3) Anything else you recommend ?

 

[Vic Spanner]

1.The new thermistor will clip into the housing securely
2.Heatsink shall be applied..puts loads on (Try Regin heat sink)
3.When it was serviced was a new electrode kit and harness fitted (5106567).Also proballay a good idea to change the board (5106568) and was the fan speeds checked.