Strange noise from double check valve (1)

[Treehobbit]

Hi all,

First post here. I have just installed a new water mains to the house. As soon as it enters the house I have stop tap reducing the 25mm mdpe to 15mm copper. I have fitted a double check valve straight after the stop tap followed by a drain tap and then connecting to the existing plumbing.

As soon as the water stops, ie the toilet finishes filling or a tap turned off I get an awful sucking noise coming from the double check valve. I have removed the valve and I can confirm this is what’s creating the noise.

Any help would be much appreciated thanks

 

[Treehobbit]

Hi all,

First post here. I have just installed a new water mains to the house. As soon as it enters the house I have stop tap reducing the 25mm mdpe to 15mm copper. I have fitted a double check valve straight after the stop tap followed by a drain tap and then connecting to the existing plumbing.

As soon as the water stops, ie the toilet finishes filling or a tap turned off I get an awful sucking noise coming from the double check valve. I have removed the valve and I can confirm this is what’s creating the noise.

Any help would be much appreciated thanks

 

[blup]

Its the noise from the water trying to get through from the main while the valve is closing: at the same time water in the system is trying to backflow. Maybe reduce the inlet pressure somehow, or move the check valve further away if that's possible

 

[Treehobbit]

Thanks for the reply, That makes sense. There isn’t much space to run the valve further away as it t’s off straight away for the bath and sink. The system originally had a check valve outside on the mdpe pipe after the external stop tap. I may add it back with a 25mm one. I was trying to reduce connections and valves underground.

I have attached a video just to show the noise. It’s the toilet filling and you can Hear the noise at the end of the video

 

[Johntheo5]

Thats very noisy from the start, with no NRV installed is it still noisy from the start?.

 

[RandomGrinch]

I may add it back with a 25mm one. I was trying to reduce connections and valves underground.

You could try replacing the new 15mm NRV with a 22mm one, using some 22 to 15mm compression reducers?
I have used the same for my outside tap, and I believe it helps improve the flow rate (and reduce noise), over a 15mm one.

 

[Treehobbit]

The noise at the start has always been the same before any work minus a bit hissing

Thats very noisy from the start, with no NRV installed is it still noisy from the start?.