Boiler turning off after startup. Need a new PCB?

[adi1]

Boiler turns on with display and then turns off.
I think it turns off as soon as pump turns on, not sure.
Diverter valve was replaced 6-8 months ago.
There has been couple of F70 error before and after the diverter replacement.
What could be at fault? Likely cause is a PCB?

Here is youtube link of the fault-

Thanks

 

[Deleted member 267285]

Could be the pcb, but it usually goes out quicker than that. I would engage with a gas safe registered engineer as it’s not a diy job.

 

[adi1]

Could be the pcb, but it usually goes out quicker than that. I would engage with a gas safe registered engineer as it’s not a diy job.

Thanks for that.
Confident enough I can change pcb. Just not sure of it's the right course of action for the issue.
Might try changing pcb, and if fault continues will get an engineer.
Thanks.

 

[Agile]

Are you quite sure it is F70 ? That is an unusual error and could indicate a faulty PCB.

However the video of the boiler makes me think that it is attempting to fire up three times and then stopping. But that would then give a fault code and stay on whereas your display just fades away.

You seem to be very keen to change the PCB whereas I am not convinced that the fault is with the PCB. With the price of a new PCB that would be expensive if it does not cure the problem.

How old is the boiler? Is it definitely out of warranty?

A Manufacturer's fixed price repair is often a better solution where expensive parts may or may not be involved.

 

[Deleted member 267285]

Thanks for that.
Confident enough I can change pcb. Just not sure of it's the right course of action for the issue.
Might try changing pcb, and if fault continues will get an engineer.
Thanks.

I didn’t question your competence it’s illegal to work on gas appliances without the correct competence.

 

[mattylad]

Could be a dry joint on the PCB.

RGI's are not competent to repair those and will only replace.

 

[DP]

RGI's are not competent to repair those and will only replace.

But the end user is?
Let us say you repair the pcb. How do you find out what the pcb test procedure is and how do you check out the logic circuit

 

[mattylad]

But the end user is?
Let us say you repair the pcb. How do you find out what the pcb test procedure is and how do you check out the logic circuit

Did I say the end user is?
No.

If it's a dry joint and that dry joint is repaired then it's very unlikely that the PCB will be in any worse a condition than when removed from the boiler. If whoever repairs it feels that they need to run a full diagnostic test on it then it's very easy to replicate the other parts of the boiler to do so - the connection details are available in the manual. Admittedly they would not know the exact test procedure or expected values but they can be found out. However fixing a dry joint will not affect/change any settings for those.

Would you be happy if the RGI opened the boiler up, looked at the PCB and fixed a dry joint, put the PCB back and tested if the boiler worked then charged the user & walked away?
Hence my statement that an RGI is not competent to repair them.

 

[DP]

but they can be found out.

From where. From the boiler makers? Have you EVER tried?

While you are talking about resoldering dry joints, I am talking about changing resistors, capacitors, relays and semiconductors.

BTW, I am an RGI and I have changed above components.
WRT end user carrying out the task, of course there are people out there far more qualified then me but there are a lot more that cannot join two wires together ( who claim they are able to carry out allotted task). One need not look elsewhere, look at the posts here. Almost every day there is someone asking how to change a programmer or carry out a simple task. Are you saying you should let these folk repair boilers?

Going back to this post. What do you think is causing this boiler to fail?

 

[RandomGrinch]

RGI's are not competent to repair those and will only replace.

An RGI may, or may not have the 'competence' to troubleshoot and replace components on a PCB; after all, it's not rocket science - many of them have decent soldering experience.

However, what they definitely have is the knowledge, test equipment and tools to check the safety critical functions of a boiler, after a component change, or PCB repair - something that a DIY'er or electronics technician won't have.

Would you be happy if the RGI opened the boiler up, looked at the PCB and fixed a dry joint, put the PCB back and tested if the boiler worked then charged the user & walked away?

Yes, I would.
Would you be happy if a technician carried out purely a PCB repair, without checking the functionality, or safety checks on the boiler afterwards?
For a start, getting to the PCB on the Vaillant involves removing the cover; that breaches the room sealing of the boiler - a silly design IMO, but...

The outer cover of many boilers now encloses the combustion airflow and is the Room Seal for the boiler. Its removal, even if only to access boiler wiring, therefore requires a GSR Engineer

DIY GAS

IS DIY GAS LEGAL? Diy gas work is not illegal, BUT, the law does require that only competent people may work on gas appliances. You also have to be able to test anything you've done, so you need the right equipment and have the right qualification to use it. The Gas Safety Regs 1998 states...

www.diynot.com

 

[DP]

Would you be happy if a technician carried out purely a PCB repair, without checking the functionality, or safety checks on the boiler afterwards?

There are several sellers on the web who proclaim to recondition pcbs. Recently bought a reconditioned pcb that appeared to have been cleaned only but did not work. Thus strengthens the argument made above. Repairing a boiler requires the repairer to don different hats to address different issues with luck playing a big part.

 

[mattylad]

Boy your certainly plucking stuff out of the air that I never said.

As for finding out, I work for a boiler manufacturer, I build and install the electronics in them daily - so yes I can find out.
So you can go stick that in your RGI pipe and smoke it.!!