Potterton Expert needed

[nick]

I have a potterton suprima 40 bolier that has developed a fault, one in a long list. I had the lockout problems some time ago and re-soldered all the joints on the PCB which cured that fault. This fault, the boiler will light, but the green light carries on flashing instead of constantly on, then the bolier switches the flame off and retries again, same thing. Sometimes the bolier will light ok and the green light stays on constantly. How does the boiler now if it has lit correctly, does it use the thermistor to signal that the flame is lit?. Hope this makes sense. cheers nick

[tony sayer]

In article , nick writes

Simple advice?, leave the doors to your gaff open one night in the hope someone will nick the poxy thing and then get something better:)

Geoff will be along shortly to be more helpful no doubt:)

[Coherers]

constantly.

Does the green LED flash slowly (2Hz) or rapidly (16Hz) ?

Have you run through the fault finding chart at p34+ of the manual. If not, the manual is available online at

[nphillips]

>The green light flashes rapidly even when the burner has lit for approx 2 seconds then the burner goes out and tries to relight. When the bolier lights and stays >>in the green light stays on.

be the problem?, on page 34 it says "control checks for flame detection within 3 seconds", how?

[nphillips]

The Green light flashes rapidly, the bolier lights, the light carries on flashing rapidly, then after approx 3 seconds the boiler goes out and the sequence starts again. On page 34 No. 8 it states "control checks for a flame detection within

3 seconds", what detects the flame is lit. cheers nick

[Coherers]

I believe there is a "Combined Flame Sense and Ignition Electrode" (see bottom p.32)

[Jeff Allen]

Had the same problem with mine a while back. Replacing the eletrode lead fixed the problem.

[Charles Fearnley]

Check the spark/detection gap - used for both functions. The way it works, is that the PCB triggers the spark across the electrode gap, then switches the electrode to an electronic circuit that looks for something like a diode, seen when there is an active flame.

Our Suprima had exactly this fault from new, and is only happy when the gap is at, or just smaller than, the specified gap. The gap is not critical to the spark generator, but is critical to the flame detection circuit, giving the effect you describe if the gap is too big

If you need the gap spec email me and I'll dig out the manual

Charles F

[raden]

In message , tony sayer writes

Da daa

It sounds like it's not flame sensing. It should spark 13 times and then go into lockout if it doesn't flame sense in that time

The Suprima 40 senses the flame by a rectification process which is sensed by the electrode and the HT lead.

If the electrode is not in the flame or the HT lead has broken, or there is a fault with the flame sensing on the pcb, you'd get this problem.

IIRC the HT lead (which is a carbon fibre one) has a resistance of about

10kOhms - measure it, giving a GENTLE tug to ensure there's no break in it.

Check that the electrode is in the flame

If both of the above are OK, it would point to the PCB being faulty

my website's at