Noisy Baxi 80 HE boiler

[khlv374]

I have an instant Baxi 80 HE combination boiler with preheat. The boiler is making a lot of noise during pre-heat and on call for hot water. It can be described by an aggressive cat noise but more prolonged. If you don't have the CH on for a while the problem goes away after a few days, but after having the CH on the problem returns. There is no noise when the boiler is in CH mode. I should say that the system is not that old. When we recently drained the system the water was not that filthy and the boiler is only about 3 yrs old so i didn't think it would necessarily be sludged up. I have read some threads about 'O rings on the diverter valve'. Could it be this (is there a test) or is it something else?

Thanks, Paul

 

[baxpoti]

Without hearing the noise it's difficult but an aggressive cat (whinnying high pitched) could be the 'O' rings

 

[kevplumb]

it's difficult but an aggressive cat

like it

 

[baxpoti]

It can be described by an aggressive cat noise but more prolonged.

Ops description not mine

 

[khlv374]

Yes when i say aggressive cat it's probably more like tearing phone books in half, like a ripping/sloshing/swooshing, not high pitched.

All other boiler operation is fine, just the noise on pre-heat/hot water.