Anybody had a PCB blow after turning a boiler off and back on again?

[Timmy D]

I’ve had it happen on a Vaillant. Zero water on the pcb. Powered down and back on and poof, dead board. Typically happens when there’s been a leak in the boiler and inside the boiler is humid.

I have also then used a hair dryer to heat the board for maybe 20 secs and the boiler then turned on.

 

[Bev GG]

Depends what he meant by 'heating the relays'. The soldered joints associated with a relay can fracture after a long period of operation because they are vibrated every time the relay operates. If arcing hasn't caused too much damage 'reheating', i.e. desoldering, the joint may fix the problem or, at least, reset the clock before it happens again.

Boards often do seem to fail at power up but this is not cause and effect. A fault can develop while the board is running normally but only manifest itself when the board is cool and/or under startup, e.g. in-rush, conditions.

To clarify the engineer claimed that heating the relays with a hairdryer would often make a dead PCB work again, not re-soldering the joints'
When you say often, could you elaborate with how many years you have been working on boilers and how many times that you have observed PCB failure at power up. Thanks.

 

[Bev GG]

Yes, I’ve not had it personally, but believe pcb’s can blow when power is turned off on and back on. Could have heated using a hairdryer, which may sound daft, but believe to work too, again, not something I’ve done personally.

Thanks for the reply. Out of interest how many years have you been working on boilers and never had a PCB blow when turned off and back on? As for heating the relays, yes it does sound daft, any suggestion as to why you believe that it might work?

 

[ShaunCorbs]

I’ve had loads had one gloworm hxi and vaillant eco this week due to power networks upgraded shutdowns also had a few Worcester fan pcb blow this year when we had the cold spell

3 months ago I had an old Worcester Cdi turned it off to do a diverter valve replacement turned on and wouldn’t work due to being off for 2 hours

 

[Deleted member 120897]

Thanks for the reply. Out of interest how many years have you been working on boilers and never had a PCB blow when turned off and back on? As for heating the relays, yes it does sound daft, any suggestion as to why you believe that it might work?

I’ve been working on boilers for about 5 years now and only had the pcb fuses blow, not the actual pcb, but our housing stock although quite vast has the same type of boiler. I think I might have had one actually blow, but that was due to a wiring fault, not turning off and on again. It’s what I’ve read/heard about, not done personally. I have used a hairdryer on a boiler once, but it was to dry the wiring harness following a leak.

 

[Scott_D]

Yes, I have had a worcester fan pcb and Vaillant Pcb go

 

[Ric2013]

I am relatively inexperienced but it happened to me on a Glow-Worm heat-only boiler. Turned it off to convert system to Y-plan. Fired system back up; all radiators getting hot; lagging a pipe; re-fixing a floorboard; then cough and splutter and it died. Luckily it was a mate's house, and when the RGI came and said it was just an old, shoddy, boiler that just didn't want to be switched off, my friend said it was all fair enough and got it replaced as it was also leaking.