Don't you just HATE intermittent faults

[fubar1000]

Morning all

Went out to a GLOW WORM MICRON 50FF last night with a intermittent fault.

The custard fired up the boiler in front of me & it run for about 1-2 min then went to lock-out. Then the boiler tried to fire up again but wouldn't fire up.

Removed the cover & all seems ok, couldn't see any faults.

Pump's running, fans running & the 3 ports working.

The boiler was ketterling a bit, but not much.

Wasn't there long as the custard was on her way out in a rush lol.

The boiler would light a couple of times (but not every time) then go to reset.

Any common faults with these guys????

Thanks peeps

 

[Barry98]

Dry joint ? Dodgy lead connection

 

[villa_tom]

I can't stand them. I'm alright on repairs but don't do them enough to be able to diagnose niggly faults. I'm quite lucky that the office where I work know this and look after me quite well.

The majority of my work is service and radiator work, but when I do repairs I get the "all off" type jobs where the boiler is just not working at all.

I don't have the patience for intermittent faults, I've never wanted to be a breakdown engineer and have no interest in that side really. I like serving and fitting rads and cookers and altering pipework.

So in answer to your question. NO, I HATE INTERMITTANT FAULTS

 

[mfgs]

The PCB's on the microns aren't great. When it wont fire up, is it sparking and not igniting or not sparking?

 

[ambrosia]

could be sticky gas valve, in fact that would be 1st place i'd look, although check youre getting signal from pcb to rule that out as well
if its sparking but not lighting its going to be one of the 2 (unless its flame rectification)

I had a stupid intermittent which i've finally figured out today.
previously the fault just wouldnt happen while i was there, turned out the expansion vessel had gone, boiler was over pressurising and shutting down. Odd thing was prv never went so when it cooled down didnt need topping up and the aav didnt look distressed.
Thinking about it hope i'm right, fitting new one thurs

 

[buckley plumb]

pcb as stated above but if you change the pcb change the thermistor as well new boards dont like the old thermistor

 

[fubar1000]

The PCB's on the microns aren't great. When it wont fire up, is it sparking and not igniting or not sparking?

When it goes to lock out/reset it dose not spark, but when it dose spark it lights, strange I no. Out of 10 times or so I tried to light it the fan would run every time, but it would only light once or twice out of ten. I'm not 100% it's the PCB or gas valve & really don't want to change 1 & it turns out to be the other lol

Thanks for all the advice peeps

 

[ambrosia]

my mistake thought it was sparking but not lighting. in that case its not the gas valve or flame rectification

fubar i need more info, where does it break down,
what you need to do is work out exactly where its going wrong, boilers go through a sequence and where it stops in that sequence will help you pin point whats going on, does the pump run, does the fan run is the solenoid opening etc etc

hey that was my 300 post, i'm expecting a cake or a bottle of champagne

 

[fubar1000]

my mistake thought it was sparking but not lighting. in that case its not the gas valve or flame rectification

fubar i need more info, where does it break down,
what you need to do is work out exactly where its going wrong, boilers go through a sequence and where it stops in that sequence will help you pin point whats going on, does the pump run, does the fan run is the solenoid opening etc etc

hey that was my 300 post, i'm expecting a cake or a bottle of champagne

Firstly the fan runs first time every time if the boiler lights or not, pump runs (only 10-12 months old) & I'm 99.9% sure the gas valves ok, I'm mostly thinking PCB but for some reason I'm still pulled to a sticky gas valve
Thanks for the info mate

 

[mfgs]

Sounds like APS problem to me. Test to see if it is switching, if its not making then it wont spark. Could also be a weak fan which would explain it dropping out after a couple of minutes when it does light.

 

[fubar1000]

See INTERMITTENT problems.... LOL

 

[REDSAW]

had one just before xmas, it was the fan.

 

[arran197]

I had the same thing on a micron. I changed the APS & I haven't been back, but other engineers may have done, so I can't be 100% sure that was the problem. Its certainty a cheap place to start though.

 

[buckley plumb]

as others have stated -if it does not spark then its not the gas valve as stated check for voltage at gas valve to be sure if you want to proove it. check fan venturi and aps tubes for damage - temp short aps common and nc to test its a process of elimmination.