intermittent boiler lockout fault logic

[cobra]

hi all
on intermittent combi boiler lockout faults does the voltage go back to the point of the fault ie then can test for voltage at
certain points of boiler sequence? any guidance /feedback on developing some type of fault finding logic on intermittent boiler fault lockout problems. thanks

 

[aggis]

Repairing boilers requires an understanding of the boiler sequences, then visual mechanical movement, voltage,continuety & resistance tests.
If new to this, go on a few different Manufactures training course.
Intermittant problems are a pain, you often need to see the boiler breaking down!
Ringing a helpline with a intermittant fault can often end in ' you can try this or that'
Then you've got to decide which part to fix? If you explain that to the customer always try the cheaper part 1st.
Repairing boilers is all about experience, but you'll never stop learning.
Good luck

 

[cobra]

thanks aggis. just dont want to be a part changer. I am new to fault finding but know the basic combi boiler sequence but not sure how to apply when intermittent lockout occurs ie would where the voltage ends up ie if it was a failing pump would the voltage go upto that point or would for example if voltage ended up on hot water thermister or heating thermister possibly then we could end up narrowing problem down to heating or hot water components or wiring. sorry if i sound abit confused. will definately go on some manufacturers courses. has anybody bought mr combi dvd- does it show him testing live voltages at combi pcb to component etc .could

Repairing boilers requires an understanding of the boiler sequences, then visual mechanical movement, voltage,continuety & resistance tests.
If new to this, go on a few different Manufactures training course.
Intermittant problems are a pain, you often need to see the boiler breaking down!
Ringing a helpline with a intermittant fault can often end in ' you can try this or that'
Then you've got to decide which part to fix? If you explain that to the customer always try the cheaper part 1st.
Repairing boilers is all about experience, but you'll never stop learning.
Good luck

 

[diamondgas]

Cobra - Question the custard first. Try to establish when they find the problem occuring. Not always helpful but you never know your luck. I tend then split it to either heat related or operational related. if that makes sense? Like overheat lockout or ignition lockout! Then it depends on the appliance! We've all got to start somewhere. If you're not sure and have the facility, ask someone with more experience to help you out!

 

[armourer]

You will need to know at what stage of operation it locks out and the only way to be sure of that is to be stood in front of it with the case off when it does fault.
All combis work in pretty much the same way (or same start up sequence any way).
Find out how far into that start up sequence it gets, eg does the fan run, does the pump run is aps making?

All I would say is don't automatically think its a component fault. Do a visual and continuity check on all wiring looms and check all terminals.

Oh! and in answer to you original question, No, once the boiler has locked out all voltages drop out so nothing to trace.

It might be worth posting make and model as for instance ideal isars flame sensing leads get trapped and short against the boiler case only once they get up to temperature.

 

[cobra]

thanks diamondgas

Cobra - Question the custard first. Try to establish when they find the problem occuring. Not always helpful but you never know your luck. I tend then split it to either heat related or operational related. if that makes sense? Like overheat lockout or ignition lockout! Then it depends on the appliance! We've all got to start somewhere. If you're not sure and have the facility, ask someone with more experience to help you out!

 

[cobra]

thanks armourer for answering original question

You will need to know at what stage of operation it locks out and the only way to be sure of that is to be stood in front of it with the case off when it does fault.
All combis work in pretty much the same way (or same start up sequence any way).
Find out how far into that start up sequence it gets, eg does the fan run, does the pump run is aps making?

All I would say is don't automatically think its a component fault. Do a visual and continuity check on all wiring looms and check all terminals.

Oh! and in answer to you original question, No, once the boiler has locked out all voltages drop out so nothing to trace.

It might be worth posting make and model as for instance ideal isars flame sensing leads get trapped and short against the boiler case only once they get up to temperature.