Worcester 30CDI banging when not in use!!!???

[sammathias]

Hey all, trying to get to the bottom of an intermittent fault on a 5 year old worcester 30cdi.
Basically most times the heating has been on for a while and is switched off the boiler makes banging noises awhile after!! i personally am yet to experience the noises as im never around long enough, but the customer is adamant. Anyone come across this before??

I done a full service on the boiler today, adjusted the co/co2 readings slightly.
fan pressure was fine at -4.8
working pressure 19mbar.
Ran the boiler upto temp, no noises.

Rang technical who where not very helpful what so ever.

Any ideas would be much appreciate? :clap:

 

[ShaunCorbs]

Anti seize pump mode ??

 

[sammathias]

Cheers for the fast reply shaun, just read up on the pump anti seize. this says the pump will run after 24 hours of inactivity. this banging noise happens an hour or so after heating is turnt off....even so... surely it shouldnt make a loud banging noise? if it was happening prematurely, would it be a pump fault or possible pcb?
Usually get half decent advise off technical but this guy basically just said if all your checks are good and you havent heard the banging yourself how is he suppose to know there even is a fault. Well because they wouldnt be calling me out for nothing fella!!!

 

[ShaunCorbs]

Expansions noises you checked expansion vessel ?

 

[sammathias]

i never checked the vessel pressure but i did ask if they ever have to top pressure up/ does pressure rise high and they said no never...

 

[hammers4spanner]

The only time i have come across 'banging' its usually followed by a blockage

 

[jonnyswamp]

Is it definitely the boiler making a noise and not coincidental water hammer

 

[aggis]

May be if there's a zone valve on the system it could be a stuck micro switch putting live thro' when off, causing boiler to fire.

 

[Leo21]

Filling loop left or seized open, prv banging?

 

[sammathias]

Customer is addament its the boiler, as for water hammer there is a vessel fitted on the cold feed to the boiler, as for filling loop its integral with key removed and prv isilnt passing. Thanks for all the comments tho. Would be great to get to the bottom of it!

 

[Leo21]

The plate hex might be knackered, giving the same symptoms as stuck open loop.

 

[kb76]

Faulty zone valve? Drayton 2 ports can cause a bang if its buggard. Pull the arm across and let it go and see if it bangs