cavitation???

[gasfit247]

Hi I wonder if any one can help me please. My ch heating is an open vent yplan when I have the heating on the pump is quiet but when ive hot water only its very noisy . Is this cavitation ? & if so how do I cure . There is no bypass valve at the moment would this help? Any help gratefully received simon

 

[nysk2008]

Very much doubt a BPV would do much, when did this start and have you had any recent work done, any pics? describe the noise?

Hi I wonder if any one can help me please. My ch heating is an open vent yplan when I have the heating on the pump is quiet but when ive hot water only its very noisy . Is this cavitation ? & if so how do I cure . There is no bypass valve at the moment would this help? Any help gratefully received simon

 

[gasfit247]

hi there I fitted a new boiler pump & dv in april ive had no problems till now

 

[nysk2008]

is the boiler kettling?

 

[gasfit247]

No I don't think so, the pump is making a knocking noise also when I first turn on the hot water I can hear the water circulating quite loudly .

 

[plumber0808]

Is there a balancing valve fitted to the flow or return on the cylinder?

if there is check its open enough to allow a decent flow, or maybe theres some crud in the valve restricting it slightly.

 

[gasfit247]

Hello I don't think so, but there is what looks like an automatic air bottle on the flow ta the cylinder this does look seized up .. but I don't think its a check valve is it???

 

[lame plumber]

soumds like air in system, had the same on a duo tec this pm, having drained down to fit an expansion vessel below boiler, no fretting, the cupboard was fitted round the boiler such that i couldnt get the side mounted boiler expansion vessel out!!!!!!!!!!!!!!!!!. I thought the impellor had fallen off the pump until I managed to bleed all the air out, thankyou to all those who insist on shuttting AAvs!!!