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?

Thanks

John

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)

See part number 11350 at www.bes.ltd.uk for an example.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

See part number 11350 at www.bes.ltd.uk for an example.

Oops, sorry that was an expansion vessel - try 11355 instead.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

wrote:

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.

Indeed - my bad - must have been half asleep posting again! ;-)

In fact, as it happens on hot and cold that would suggest the mains cold
feed to the boiler.

I would try securing pipes, and if that is insufficient then a shock
arrestor.

yup

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 22 Feb, 16:01, John Rumm wrote:
wrote:
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.

Indeed - my bad - must have been half asleep posting again! ;-)

In fact, as it happens on hot and cold that would suggest the mains cold
feed to the boiler.

I would try securing pipes, and if that is insufficient then a shock
arrestor.

yup

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

I also suffered severe hammer from the toilet taps immediately after
our new WB combi was fitted. After supporting a corner of pipework
(hot & cold) left to wave about by the otherwise tidy installer - to
no avail - I decided to replace the existing taps with ceramic insert
types. Instant cure!! It seems the old washer based taps can be
overwhelmed by the high pressure of the hot supply from a combi,
though this didn't explain why the cold side never had a problem with
the rising main. Perhaps just a weak washer....Hope this is of some
help.

On Thu, 22 Feb 2007 09:29:36 GMT, wrote:

|!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.
--
Dave Fawthrop sf hyphenologist.co.uk 165 *Free* SF ebooks.
165 Sci Fi books on CDROM, from Project Gutenberg
http://www.gutenberg.org/wiki/Main_Page Completely Free to any
address in the UK. Contact me on the *above* email address.

On Wed, 21 Mar 2007 08:03:41 +0000, Dave Fawthrop
wrote:

|!On Thu, 22 Feb 2007 09:29:36 GMT, wrote:
|!
|!|!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.

Sorry wrong thread :-(
--
Dave Fawthrop sf hyphenologist.co.uk 165 *Free* SF ebooks.
165 Sci Fi books on CDROM, from Project Gutenberg
http://www.gutenberg.org/wiki/Main_Page Completely Free to any
address in the UK. Contact me on the *above* email address.