Suprima 40 Problem

[Perkinsg]

There seems to be a recurring problem with Potterton Suprima boliers. Mine is a Suprima 40, 4 years old. Anyone have any ideas as to what might solve this problem?


Symptoms:

Boiler heats water and room temprerature to required level and then goes to standby mode. When there is a further call for heat, ignition tries three times and then locks out with flashing red light.

Manual re-ignition is always successful, except if tried when the boiler has just finished operating for a lenght period. In this case, leaving it for a few minutes before manual re-ignition is always successful.

If only the hot water is on, the boiler will remain active, firing intermittantly to keep water temperature at required level. However, as soon as the heating comes on, and reaches required room temperature, ignition tries three times then locks out. The same would occur if only the water is on, and a bath is drawn. The water would be heated, and then a lockout occurs.

Actions to date:

My plumber has all but given up with this. ThePCB has been changed (though the original did not show any clear sighns of damage. Manual ignition switch changed (though not sure why as the previous one worked fine), heating pump changed (though this was a non-related issue). Spark distance seems OK, voltage seems OK, fan OK etc.

At a total loss and on the verge of giving up and getting a new boiler which is painful.

Any ideas? Thanks.

Gary Perkins

 

[Gas2Air]

There is a modified gas valve available for the Sups, check on the gas valve solenoids for a number stamped 401, if 411 then get the gas valve changed. Is polarity ok? Has the engineer checked inlet/working pressure? Resistance readings of components? Temp sensor can go faulty on these boilers too, get him to check that.

 

[MANDATE]

Also worth checking is the high voltage lead to the electrode, potterton did once suggest this may short across to boiler frame, so the spark would not occur at the electrode gap.
Also worth checking is the air pressure switch. Fan creates vacuum on diaphram and operates microswitch.
I see the pcb been changed but is the replacement the improved version I wonder. You could examine the pcb for poor soldering. With a magnifier I found lots of cracked soldering at the terminal posts explaining why my fault was intermittent.