Boiler goes Bang when cooling down.

[stuart123]

Hello,

I'm hoping somebody can help and shed some light onto this problem. I have an issue with my Procombi HE 83 boiler, when the boiler turns off after the heating has been running, 10- 20 minutes later there is a single very loud bang. the volume of the bang is dependant on how long the boiler has been on, it's loud enough to wake me up, aside from that it works fine, the pressure / temp gauge does not spike, there's no kettling and the system has been bled, I am at a loss.

I have had 2 heating engineers around, the 1st guy scratched his head, the 2nd checked the expansion vessel and told me if I exchange the Heat Exchanger that should fix the problem, although he did not leave me with a lot of confidence, the pump works fine.

I have read that it could an issue with the port valve, but i'm not sure if I have one of those on my system, this problem has been going on for about a year since I had the location of the boiler moved, the pressure of the boilr is 1 at cold and rises to 1.8 when the heating is on, its a combi style of boiler.

Thanks for you help

Stuart

 

[Jay Jay]

The noise is due to it shutting off v temperature(expansion)Either divertor is sticking/slamming via spring or there isn't enough movement through your bypass if you have one?
Get your engineer to investigate that route and let us know how you get on

 

[stuart123]

Hi Jay, Thanks for you help, I am due to see an engineer next week. I will point him in that direction, I will keep you informed.
Thanks Stuart