|!On 22 Feb, |! John Rumm wrote: |! |!> John wrote: |!> |!> > Just had to have a new combi boiler fitted (Worcester Bosch) and the |!> > location of the boiler had to be changed in the garage due to current |!> > regs with flues being near to doors etc. Since this was done, we are |!> > getting loud knocking noises when both hot and cold taps are turned off |!> > suddenly. I've had a look at the ofefnding pipes which are in the garage |!> > near to the boiler and there is quite a lot of old piping which doesn't |!> > have regular brackets fixing it to the wall. Would fitting more brackets |!> > solve the problem or do I need to get some kind of valve fitted to stop |!> > the water hammer noise? If the latter is the case, it is likely to be |!> > expensive and would the boiler need draining as that would involve |!> > refilling with inhibitor? |!> |!> More supports will most probably improve thee situation. If that alone |!> does not fix the situation then fitting a shock arrestor ought to help. |!> These are easy enough to fit, but would require some draining down (and |!> hence inhibitor replacement) |! |!Why drain down the CH side? the problem appears to be on the potable warer |!side, so no inhibitor involved,. Clue -- happens when /cold/ water shut off |!quickly, as well as hot. |! |!I would try securing pipes, and if that is insufficient then a?shock |!arrestor.
Thanks! but I have now shown that it is *definitely* the downstairs heating valve, by playing with the controls.
The CH is grossly over powered for the radiators fitted, so there is much too much water being pumped around. Can you turn down the output of the CH pump? My boiler is a Baxi 105 Instant.
I was also thinking of draining a bit of water out of the CH and adding new water, then some air would boil out into the radiators.