Firebird Combi enviromax c20 Riello Control Box, 535 SE / LD lockout

[Stevie187]

Hi all,

I have been fixing a few problems with the above boiler for a while now so far they have been easy fixes, motor start cap, photo sensor etc. This one is starting to frustrate me though. So I get a random lockout after minutes hours of running as far as I'm aware the 535se/LD doesn't give much diagnostic information out when it locks out? So following the diagnostic flow it's check motor 50 volt to white wire, check solenoid, check photocell(replaced recently) then replace control box!

I haven't check any of the above yet what are my chances of catching these if it's an intermittent problem? I would have liked a bit more diagnostic information but I guess it's a few years old now. Anyone got any pearls of wisdom for this old boiler before I start my troubleshooting journey?

Thanks

Steve

 

[muggles]

Does it lock out with increasing frequency after the first reset?

 

[Stevie187]

Thanks for the reply muggles just caught the lockout in action and it seems to be a previous problem not resolved. It locks out trying to spin the motor up I thought I had fixed this with replacement cap. Granted it was cheapo of equivalent spec but wouldn't think it would have failed that quick, it had seemed to have fixed it for a few weeks. Either that I suppose or motor is on its way out? Somebody mentioned take the pump assembly off and check the movement on the shaft.

 

[Terrywookfit]

Yes check oil pump shaft foŕ tight spots. Also drive dog.

 

[Stevie187]

Thanks Terry, Check the pump or the motor? So the drive dog is the plastic coupling between the motor and the pump right?

 

[Terrywookfit]

Yes the pump shaft. Slowly turn it and feel for any tight spots.
Yes plastic dog.
Did you fit correct uf cap.

 

[Stevie187]

Yeah it was 4.5uf like the original but it was an unbranded cheap one, which was weird as that seemed to fix it for a while and then slowly it came back not unless a fresh cap gave it a bit of a boost to get going for w while. I have noticed it seems to run for longer when it's cold, it could be though it's cycling less and just fully on more.

 

[Stevie187]

Also the other problem has come back the CH pump now doesn't run, the DHW is constantly running I think there a problem with the flow detector thermistor.

 

[Stevie187]

I unplug the thermistor turn it on and the lights flash to say it's detected a problem, turn it off plug it back in and it's fine for a while. I'm going to get somebody out but fear they will try and say a new boiler.

 

[Mike2007]

Did your burner problem get resolved, as mine is being just as awkward?

 

[Stevie187]

Yes it was the pump in the end, had a local plumber guy out who diagnosed it whipped the pump off and it felt quite stiff at some points he had a spare in the van. At first he took just the snorkal part off to get to the fan and gave it a spin said it felt stiff took the rest of it apart and swapped out pump. The new pump seemed to be set at the right pressure but if you have no way of measuring the fuel pressure its not really a DIY job.