pipe knocks when hot tap turned off

[Gembo]

Hi everyone,

Whenever I turn off the hot water tap in the kitchen the pipe that's in the cupboard further on, (not directly under the sink) makes a knocking noise.
It's not a constant tapping as I have read about water hammer, but maybe knocks a couple of times with a pause in between then it will do it again maybe a few minutes later, maybe longer.

Does anyone have any ideas please?
Could it be the pressure is too high? or an airlock?

Please reply in simple terms for me as I don't know much!

thanks a lot
xGem

 

[petetheleak]

sounds like you need an excorcism. No but really on basic info given on system if you got a tank fed system you prob need a new washer on tank ball valve and clip pipework, process of elimination really . let us know if that does the trick if not other things can be done but one step at a time .

 

[larrytheleak]

make sure pipe is clipped properly as first priority where knocking is coming from

 

[seco services]

http://www.youtube.com/watch?v=LiHMbgI8Ox8&feature=related

 

[Gembo]

Hi Larry and Pete,
The pipe I thought the knocking was coming from isn't that one in the cupboard (bit embarrassed to say that's a gas pipe!! lol) but it sounds like it's underneath, we can hear it more from the next room.

We have a combi boiler.

Turned the pressure down and this hasn't helped.
Maybe we will have to get someone in to look at them to make sure they're clipped properly?
Its a new property, but doesn't surprise me as they rushed the development an everything is a bit rubbish!

thanks guys
xG

 

[gas_man_gaz]

could be dew due to high water pressure from ya cold mains.. does it do it on both the hot and cold taps? ya could try fitting a mini exspansion vessel/shock arrestor

 

[Gembo]

Hi Gaz,
Nope only the hot tap or washing machine
thanks
xGem

could be dew due to high water pressure from ya cold mains.. does it do it on both the hot and cold taps? ya could try fitting a mini exspansion vessel/shock arrestor

 

[gas_man_gaz]

what boiler ya got? its not a ideal isar is it?
presume ya washer has a hot feed to it then?

 

[Gembo]

its a glow-worm 30ci
and yes I guess it has!

what boiler ya got? its not a ideal isar is it?
presume ya washer has a hot feed to it then?

 

[gas_man_gaz]

2b honest not sure why it wud bang on jus the hw, ya cud adjust the mains into the boiler and see if that makes a difference

 

[Gembo]

Thanks Gaz, not sure how to, so I guess a plumber is in order.

Its weird as its doing it now with the dryer on. Its a combined washer/dryer and I hear water come on when I switch the dryer.

2b honest not sure why it wud bang on jus the hw, ya cud adjust the mains into the boiler and see if that makes a difference

 

[keego]

When you say you've turned the pressure down I presume you mean you've turned the stop tap down a bit, this can introduce a knocking noise as well.
Try opening the stop tap fully & see if that helps.

Its weird as its doing it now with the dryer on. Its a combined washer/dryer and I hear water come on when I switch the dryer.

I,m no expert on washer driers but I'm almost sure they use cold water intermittently during the drier cycle, something to do with the condenser I think.

 

[Gembo]

Thanks Keego, thats interesting to know.
ok, will try to open the tap up fully, see what happens.

When you say you've turned the pressure down I presume you mean you've turned the stop tap down a bit, this can introduce a knocking noise as well.
Try opening the stop tap fully & see if that helps.

Its weird as its doing it now with the dryer on. Its a combined washer/dryer and I hear water come on when I switch the dryer.

I,m no expert on washer driers but I'm almost sure they use cold water intermittently during the drier cycle, something to do with the condenser I think.