Knocking noise from water system

[BillandCath]

Hi
We have an Airstream Ace 680FB 2007
Had it 5 years now, but since day one every time we run water, a loud knocking noise comes from the washroom area.
We have changed the pump and the shower tap. We have tried bleeding the system when we filled up with fresh water, to no avail.
We have checked for are leaks also.
Is there any device under the motorhome that may be causing issues?
Look forward to hearing a solution so we can give the world a quieter life.
Cheers

 

[Landy Andy]

Can you get to pipes? Sounds like the need clipping or protecting to stop the knock as pump pulses.

 

[BouncyBoatFolk]

Are you able to run the Hot an Cold at a separate times, does it do it on both pipe runs?
Does the knocking increase with the increased volume demand as the taps are opened further?
Does it do it if only the kitchen taps are opened?
As Andy says though, it's probably a bend in the pipe run that's resonating against a hollow floor or a wall in harmony with the pump.
Mike.

 

[BillandCath]

Cannot get access to pipes without taking wall down.
Can run both hot and cold.
Knocking noise is the same whatever volume is run.
All taps, including toilet flush.
Might need to live with it.
Cheers
Bill

 

[Ivory55]

I am not an expert, but is there a long run to the first bend. Only a plumber I know when doing floor runs would put a bend in the pipe half way down a long run to stop pipes banging when the pump kicked in.

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[BouncyBoatFolk]

If your able to get to any of the pipe run you might be able push some lengths of pipe lagging over the pipe and along it.
This may help dampen down the noise.
Mike.

 

[pappajohn]

Mount the pump on rubber isolators.
Easy enough to make from an old radiator hose.
Screw hose to floor, screw pump feet to hose.

 

[BillandCath]

I have put the pump on rubber mounts a couple of years ago in the hope that it would solve the problem.

 

[BillyKontiki]

As above loose unsecured pipes etc. If this is a constant pulsing noise check the filters on the system if there is insufficient water passing through the pump it will pulse causing a dull thumping noise.
Hope this helps.

 

[Landy Andy]

As above. Get to where you can with the pipes and try sliding pipe insulation along them.

Also if you get with toilet flush it must either be the cold water pipe, or the supply to the pump

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[Ridgeway]

That's exactly what i've done, just slid on the pre-cut stuff and it solved the water knocking.

 

[Spanner]

As others have suggested it’s probably just an unsupported pipe causing the noise.
You could try completely removing the pump mounting screws and temporarily support the pump on a towel or similar, if the noise disappears alter the fixings or fit an inline damper.