A DIY & home improvement forum. DIYbanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » DIYbanter forum » Do - it - Yourself » UK diy
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions.

Knocking sound in central heating system



 
 
LinkBack Thread Tools Display Modes
  #1  
Old November 23rd 05, 08:09 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system

After a new boiler was installed, our CH system started knocking after
it had been running for a while. Turning the thermostat on the hot
water cylinder up higher would make the knocking stop for a while. The
guys who did the installation tried turning the pump speed down, which
helped a bit but didn't fully solve the problem.

The chap who came round to service the boiler suggested that it might
be washer flutter in one of the thermostatic valves. Today being a cold
day, the knocking started again. I went around the radiators with
thermostatic valves, and found one which seemed noisy. Turning the
valve slightly stopped the noise. Playing with the valve, it seemed to
be quite clunky.

Is there anything I can do with this valve without draining the whole
system?


--
Simon Elliott http://www.ctsn.co.uk
Ads
  #2  
Old November 23rd 05, 09:44 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system

Simon Elliott was thinking very hard :
Is there anything I can do with this valve without draining the whole
system?


Just a suggestion with no idea of its worth....

Could you try turning the valve down at the other end of the rad to
reduce the flow a little - that might prevent the clunking.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk


  #3  
Old November 23rd 05, 10:34 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system

On 23/11/2005, Harry Bloomfield wrote:

Just a suggestion with no idea of its worth....

Could you try turning the valve down at the other end of the rad to
reduce the flow a little - that might prevent the clunking.


Interesting idea! I'll give it a try when/if the problem recurs.


--
Simon Elliott http://www.ctsn.co.uk
  #4  
Old November 23rd 05, 11:41 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system


"Simon Elliott" Simon at ctsn.co.uk wrote in message
.. .
After a new boiler was installed, our CH system started knocking after
it had been running for a while. Turning the thermostat on the hot
water cylinder up higher would make the knocking stop for a while. The
guys who did the installation tried turning the pump speed down, which
helped a bit but didn't fully solve the problem.

The chap who came round to service the boiler suggested that it might
be washer flutter in one of the thermostatic valves. Today being a cold
day, the knocking started again. I went around the radiators with
thermostatic valves, and found one which seemed noisy. Turning the
valve slightly stopped the noise. Playing with the valve, it seemed to
be quite clunky.

Is there anything I can do with this valve without draining the whole
system?


An old chestnut reply is to ask if the valve is fitted the right way round
for the water flow. Older TRV's will rattle if the flow is backward, these
should have an arrow or indicator to show the correct flow direction. Some
newer valves are bidirectional

bland




  #5  
Old November 24th 05, 10:39 AM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system

Funny enough I'm having a similar problem.

I had 90% of my central heating system re-plumbed recently, the other
10% was replaced a couple of years ago. When the Boiler starts up I
hear a tinkering from some of the valves, it something to do with the
flow of water - turning the valve down reduces the noise. I haven't had
some time to investigate.

  #6  
Old November 24th 05, 10:26 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system


"Simon Elliott" Simon at ctsn.co.uk wrote in message
.. .
After a new boiler was installed, our CH system started knocking after
it had been running for a while. Turning the thermostat on the hot
water cylinder up higher would make the knocking stop for a while. The
guys who did the installation tried turning the pump speed down, which
helped a bit but didn't fully solve the problem.

The chap who came round to service the boiler suggested that it might
be washer flutter in one of the thermostatic valves. Today being a cold
day, the knocking started again. I went around the radiators with
thermostatic valves, and found one which seemed noisy. Turning the
valve slightly stopped the noise. Playing with the valve, it seemed to
be quite clunky.

Is there anything I can do with this valve without draining the whole
system?


Yes - leave the valve fully on or fully off.

I have the same problem, since installing a new boiler. I suspect one or two
valves were put in the wrong way around, but it did not cause a problem with
the old pump. The new pump more powerful and so is causing the valve to
knock. Next time the system is emptied, I'll turn the valves around, but in
the meantime, leaving a few valves fully on is not too big a problem.

-- JJ


  #7  
Old December 1st 05, 08:12 AM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system

On 23/11/2005, bland wrote:


An old chestnut reply is to ask if the valve is fitted the right way
round for the water flow. Older TRV's will rattle if the flow is
backward, these should have an arrow or indicator to show the
correct flow direction. Some newer valves are bidirectional


I think you've hit the nail on the head. I assume that the water is
flowing from the hotter radiator pipe to the cooler one, and if so,
it's fitted back to front. Looks like I'll need to wait till the next
time I want to drain the system.


--
Simon Elliott http://www.ctsn.co.uk
  #8  
Old December 1st 05, 10:33 AM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Knocking sound in central heating system

In article ,
Simon Elliott Simon at ctsn.co.uk wrote:
Today being a cold day, the knocking started again. I went around the
radiators with thermostatic valves, and found one which seemed noisy.
Turning the valve slightly stopped the noise. Playing with the valve, it
seemed to be quite clunky.


Some TRVs can only be fitted on (usually) the flow side. They'll often
have an arrow on them denoting direction of flow. Fitting them on the
return can give the symptoms you describe. So check by seeing which pipe
gets hot from cold first - this will be the flow.

--
*I'm not being rude. You're just insignificant

Dave Plowman London SW
To e-mail, change noise into sound.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Wiring diagram for old central heating system Martin Wiseman UK diy 5 October 14th 05 12:17 PM
Best way to clean and flush a combi central heating system? [email protected] UK diy 1 February 8th 05 09:23 AM
Central heating system de-sludge or just heat-exchanger de-sludge? Don Rojo UK diy 6 October 15th 04 07:13 AM
Flushing a closed central heating system aris UK diy 1 October 17th 03 09:19 PM
Draining a closed central heating system Jay and mike 1 UK diy 4 October 4th 03 04:33 AM


All times are GMT +1. The time now is 12:21 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.SEO by vBSEO ©2010, Crawlability, Inc.
Copyright 2004-2014 DIYbanter.
The comments are property of their posters.