Water hammer when there is no flow

[TAndrews1]

Hi, some help would be really appreciated. I have had some plumbing work done on my house to essentially reconnect up a gas boiler. The plumbers have done a good job but there is a constant water hammer noise from the cold main. It's all the time and happens even when there is no water flowing, i.e. through the night. The pipes are fixed well and I don't thing are knocking. So what is it? I've tried reducing the pressure of the water to the lowest usable level, i.e. trickle, and it still knocks away. I'm reluctant to fit an arrestor as it's not a normal water hammer noise.

Any thoughts or solutions would be welcome.

Thanks.

 

[footprints]

Check for leaks or water flow perhaps a garden tap just letting by a little or a WC overflow running either to outside or on modern suites directly into the pan.

 

[gigz]

Does it stop altogether when you shut stoptap off completely ?

 

[TAndrews1]

Hi, thanks. Yes, when the stoptap is turned off the sound stops completely. I've had to do this every evening before going to bed!

 

[breadnbutter]

it might be the ballvalve in your cold water storage cistern or header tank ballvalve. unless you got a unvented system.

 

[TAndrews1]

Cheers, it's a combi boiler and therefore no cold tank etc. I cant find any leaks also.

 

[breadnbutter]

have you checked, as said, the toilet cistern ball valves.

 

[breadnbutter]

have you checked the filling loop is off, as if thats on it will over pressure and **** out the prv,and make that hammer sound.

 

[TAndrews1]

Hi, sorry, yes the toilet valves seem all ok. I can't find any evidence of leaks or failure.

 

[potterton678]

Hi, some help would be really appreciated. I have had some plumbing work done on my house to essentially reconnect up a gas boiler. The plumbers have done a good job but there is a constant water hammer noise from the cold main. It's all the time and happens even when there is no water flowing, i.e. through the night. The pipes are fixed well and I don't thing are knocking. So what is it? I've tried reducing the pressure of the water to the lowest usable level, i.e. trickle, and it still knocks away. I'm reluctant to fit an arrestor as it's not a normal water hammer noise.

Any thoughts or solutions would be welcome.

Thanks.

The plumbers who did the work, what do they say?

 

[TAndrews1]

I did mention the noise on the last day there were working and they could hear it. They were wrapping up and did fix down a few of the pipes and fiddle with the pressure. Unfortunately they did not fix it. Not sure whether to call them back as they have done a good job overall.

 

[gigz]

There must be a leak/ water passing to get the noise. Turn the cold water isolation valve off under the boiler, if it stops you have narrowed it down to the hot water side (its a start).