boiler noise on start up

[archiedale]

oldish ferroli tempera, all good when running, customer has no issues but on start up its sounds like its going to jump off the wall.. done the usual bleeding extra but why this only when cold i.e morning start up and early evening start up... anyone got a ideas ?

 

[warrington]

check the spark, it may be loose spark on the start. Try to start, spark not fire more gas release in boiler and bang.

 

[archiedale]

but its only when it starts from cold, when in normal operation (room stat calling) its fine, customer lead problem but ive no reason to disbelieve. when i turn up to have a look its all good.

 

[dancinplumba]

thinking when it gets hot internals have expanded, mebe pump rattling ???

 

[archiedale]

new pump fitted as it was leaking

 

[dancinplumba]

crud in heat ex ? when on start up boiler fires on full gas rate and starts kettling till it gets warm then it modulates down ??

 

[archiedale]

yes dancin, thats what i think it is, going to try chemical first thks

 

[warrington]

archiedale can you let us know when you sort the problem.