I have just had a new Combi fitted to the old *single pipe* radiator
system. Two zones upstairs and downstairs controlled with valves. It
worked fine.

The downstairs valve was in the wrong place so I drained the system and
moved it. Crossed a thread and had to replace it with a different make.
Refilled, bled radiators, and adjusted CH pressure to 1-2 bar.

Now the problem! The system gives a *single* bang a few times a day, at
random. Random events are a pig to fault find. It sounds to me as if it
*could* be water hammer caused by the valve closing. It really does not
sound like a gas explosion, just the pipes reverberating.

What do people think? What is a good method of fault finding?

Google gives http://www.water-hammer.com/

A US site says that air chambers are no longer recommended.
http://www.builderswebsource.com/tec...aterhammer.htm
High temperature sealed are filled bladders?
--
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 Mar 18, 7:26 am, Dave Fawthrop
wrote:
I have just had a new Combi fitted to the old *single pipe* radiator
system. Two zones upstairs and downstairs controlled with valves. It
worked fine.

The downstairs valve was in the wrong place so I drained the system and
moved it. Crossed a thread and had to replace it with a different make.
Refilled, bled radiators, and adjusted CH pressure to 1-2 bar.

Now the problem! The system gives a *single* bang a few times a day, at
random. Random events are a pig to fault find. It sounds to me as if it
*could* be water hammer caused by the valve closing. It really does not
sound like a gas explosion, just the pipes reverberating.

What do people think? What is a good method of fault finding?

Google giveshttp://www.water-hammer.com/

A US site says that air chambers are no longer recommended.http://www.builderswebsource.com/tec...aterhammer.htm
High temperature sealed are filled bladders?
--
Dave Fawthrop sf hyphenologist.co.uk 165 *Free* SF ebooks.
165 Sci Fi books on CDROM, from Project Gutenberghttp://www.gutenberg.org/wiki/Main_PageCompletely Free to any
address in the UK. Contact me on the *above* email address.

Are The valves motorised? If so do you have a two seperate
thermostats, one for upstairs and one for downstairs? Does your new
combination boiler have in integral bypass if not then there is your
problem. As both the valves close the water has no where to go hense
the banging. You will need to fit an AUTOMATIC bypass between the flow
and return pipes. Usually in 22mm and a certain distance from the
boiler depending on the size of your system this will be explained in
your installation manual. You will need to set the bypass so it gives
a minimum flow rate when both valves are closed which will aslo be in
the installation manual.

Hope this helps

On 18 Mar, 07:26, Dave Fawthrop
wrote:
I have just had a new Combi fitted to the old *single pipe* radiator
system. Two zones upstairs and downstairs controlled with valves. It
worked fine.

The downstairs valve was in the wrong place so I drained the system and
moved it. Crossed a thread and had to replace it with a different make.
Refilled, bled radiators, and adjusted CH pressure to 1-2 bar.

Now the problem! The system gives a *single* bang a few times a day, at
random. Random events are a pig to fault find. It sounds to me as if it
*could* be water hammer caused by the valve closing. It really does not
sound like a gas explosion, just the pipes reverberating.

What do people think? What is a good method of fault finding?

Google giveshttp://www.water-hammer.com/

A US site says that air chambers are no longer recommended.http://www.builderswebsource.com/tec...aterhammer.htm
High temperature sealed are filled bladders?
--
Dave Fawthrop sf hyphenologist.co.uk 165 *Free* SF ebooks.
165 Sci Fi books on CDROM, from Project Gutenberghttp://www.gutenberg.org/wiki/Main_PageCompletely Free to any
address in the UK. Contact me on the *above* email address.

Ignore US sites.
The problem will be due to the new valve shutting more suddenly then
the old one. Some makes are more prone to this than others. The
Honeywell rubber ball type "usually" are least prone to it but YMMV
A shock arrester might be useful but no guarantees

On Mar 18, 7:26 am, Dave Fawthrop
wrote:
I have just had a new Combi fitted to the old *single pipe* radiator
system. Two zones upstairs and downstairs controlled with valves. It
worked fine.

The downstairs valve was in the wrong place so I drained the system and
moved it. Crossed a thread and had to replace it with a different make.
Refilled, bled radiators, and adjusted CH pressure to 1-2 bar.

Now the problem! The system gives a *single* bang a few times a day, at
random. Random events are a pig to fault find. It sounds to me as if it
*could* be water hammer caused by the valve closing. It really does not
sound like a gas explosion, just the pipes reverberating.

What do people think? What is a good method of fault finding?

Google giveshttp://www.water-hammer.com/

A US site says that air chambers are no longer recommended.http://www.builderswebsource.com/tec...aterhammer.htm
High temperature sealed are filled bladders?
--
Dave Fawthrop sf hyphenologist.co.uk 165 *Free* SF ebooks.
165 Sci Fi books on CDROM, from Project Gutenberghttp://www.gutenberg.org/wiki/Main_PageCompletely Free to any
address in the UK. Contact me on the *above* email address.

Do a basic check before anything else................. make sure you
have fitted the replacement valve correctly. On the brass body on the
underside you will see the letter A on one port and B on the other
port. Make sure water is flowing in the direction of A to B.

In an earlier contribution to this discussion,
Dave Fawthrop wrote:


Now the problem! The system gives a *single* bang a few times a day,
at random. Random events are a pig to fault find. It sounds to me as
if it *could* be water hammer caused by the valve closing. It really
does not sound like a gas explosion, just the pipes reverberating.

What do people think? What is a good method of fault finding?

It shouldn't be too difficult to check that it *is* the valves doing it. Use
the relevant room stats to cause each valve in turn to close and see whether
you then get the noise. You should be able to isolate which valve it is, and
also whether it only happens when the *second* valve closes but not when one
valve remains open.

Even if it is a valve, it's only annoying - not serious. But also see
someone else's post about a by-pass valve.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
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PLEASE REPLY TO NEWSGROUP!

On 18 Mar 2007 03:37:45 -0700, "Awesometoday"
wrote:

|!On Mar 18, 7:26 am, Dave Fawthrop
wrote:
|! I have just had a new Combi fitted to the old *single pipe* radiator
|! system. Two zones upstairs and downstairs controlled with valves. It
|! worked fine.
|!
|! The downstairs valve was in the wrong place so I drained the system and
|! moved it. Crossed a thread and had to replace it with a different make.
|! Refilled, bled radiators, and adjusted CH pressure to 1-2 bar.
|!
|! Now the problem! The system gives a *single* bang a few times a day, at
|! random. Random events are a pig to fault find. It sounds to me as if it
|! *could* be water hammer caused by the valve closing. It really does not
|! sound like a gas explosion, just the pipes reverberating.
|!
|! What do people think? What is a good method of fault finding?
|!
|! Google giveshttp://www.water-hammer.com/
|!
|! A US site says that air chambers are no longer recommended.http://www.builderswebsource.com/tec...aterhammer.htm
|! High temperature sealed are filled bladders?

|!Are The valves motorised? If so do you have a two seperate
|!thermostats, one for upstairs and one for downstairs?

Yes! I have now shown that the problem is with the new downstairs valve by
fiddling the controls



|!Does your new
|!combination boiler have in integral bypass if not then there is your
|!problem. As both the valves close the water has no where to go hense
|!the banging. You will need to fit an AUTOMATIC bypass between the flow
|!and return pipes. Usually in 22mm and a certain distance from the
|!boiler depending on the size of your system this will be explained in
|!your installation manual. You will need to set the bypass so it gives
|!a minimum flow rate when both valves are closed which will aslo be in
|!the installation manual.

The boiler is a Baxi 105 instant, which is grossly overpowered the
radiators fitted. Is it possible to turn down the output of the boiler
pump?

They did not leave me the installation manual, I will try to find it on the
Web

I was thinking of draining a bit a bit of CH water and adding some more, so
that the air would boil out and form a de facto shock arrestor.
--
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 08:20:45 +0000, Dave Fawthrop
wrote:


The boiler is a Baxi 105 instant, which is grossly overpowered the
radiators fitted. Is it possible to turn down the output of the boiler
pump?

They did not leave me the installation manual, I will try to find it on the
Web



I have the installation mnanual in front of me at the mo.

According to the manual the pump (a Grundfos 15-60) MUST be set to '3'
(maximum speed).

If you wish I could scan you the relevant bits of the manual...

--
Frank Erskine
Sunderland

On Wed, 21 Mar 2007 08:32:54 +0000, Frank Erskine
wrote:

|!On Wed, 21 Mar 2007 08:20:45 +0000, Dave Fawthrop
wrote:
|!
|!
|!The boiler is a Baxi 105 instant, which is grossly overpowered the
|!radiators fitted. Is it possible to turn down the output of the boiler
|!pump?
|!
|!They did not leave me the installation manual, I will try to find it on the
|!Web
|!
|!
|!
|!I have the installation mnanual in front of me at the mo.
|!
|!According to the manual the pump (a Grundfos 15-60) MUST be set to '3'
|!(maximum speed).
|!
|!If you wish I could scan you the relevant bits of the manual...

Thanks but I will believe you.
--
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.

In article ,
Dave Fawthrop writes:

They did not leave me the installation manual, I will try to find it on the
Web

Ask the fitter for the installation/servicing manual.
They are required to leave it with you.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]