Glow worm 60FF ultimate problems

[Eddie Charlton]

I am currently training with an experienced gas engineer. we attended a strange job today which has thrown us a bit.
the customer complained that the Glow worm 60FF ultimate boiler was not firing.
did a few checks and fornd that the fan was cycling on ond off with no ignition at all. Engineer said had seen this before and was a PCB problem. PCB changed.

now when calling for heat, the fan would come on, pressure switch confirmed on neon on PCB, and in
ignition sequence with spark. But, the gas comes on for a few seconds with main burner on, then switches off and keeps doing this constantly until you stop calling for heat.

spoke to manufacturer who stated it was a supply low pressure. which was probably affecting the rectification of the circuit.
Anyway gas board came out and changed the meter regulator and confirmed pressure at meter and boiler. (would like to add that this is a new problem and the boiler has worked fine for years.
so, with the new pcb insitue i decided to see what was happening with the voltages to the system.

when calling for heat the pilot solenoid it getting a steady 230volts.
the main gas valve however was cycling between no volts and overload as the burner cycles. my fluke mulitimeter is working correctly and has a modulating voltage range up to 600volts?

this was also present accross the pressure switch as well.

am struggling to think what could be the cause, as seems to be such a high voltoage, when the pilot solonoid is getting expected 230v. i was thinking might be main solonoid, but stuggled to explain readings. could it be somthing capacitive causing readings and thus the problem?

obviously this might have been the reason why the original pcb failed?
have not yet checked continuity on solonoid, or voltage at pins while diconnected.

any thoughts

 

[aggis]

Interesting, is the polarity right & incomming voltage?
You say it's surging At the aps aswell?
If so it all goes thro' the pcb.
Is neon 4 lit ? going on & off with the burner?
Check pilot & electrode, aswell as pilot injector on this boiler there's a restrictor in pilot tube at gas valve. Might be hit &miss with rectification.
Check flue especially the inner for holes.
It really seems to be pointing at the pcb..... hmmm

 

[Eddie Charlton]

thanks for the reply.

the 4th neon is not coming on at all.
the manufacturer seems convinced that it is a rectification problem and they state caused by Inlet gas Low pressure, taking the pilot flame off the probe by a few millimeters.

have to say it does look liker rectification, but really am having problems naorrowing it down.
rectification lead changed,
pilot assembly cleaned out
Pilot seems stable all the time we have tried it.
Polarity is correct for power supply to the unit.

will have to go over everything again.

kindest regards

 

[aggis]

Might be worth changing the electrode & pilot injector [ had a few probs with injectors seemed ok, but had to change them.
Also check your earth continuety.
Just a thought, is the pcb correctlly on its pegs in the right position. & the plugs all pushed in properly.
Good luck

 

[markinaark]

take the pilot housing apart disconnect the pilot gas tube , when you look into the housing you may see only 1 hole where gas passes through,their is 2 and 1 maybe blocked, had this problem a spent hours on it.
look very carefully and blow through housing. or use a very fine wire to assist

 

[jammydodger]

swap the two electrical spade connectors on the fan (polarity)