Pulsing Water Main

[Mattenstein]

Hi all

We had 2 bits of underground supply pipe replaced recently as we could hear a constant running water sound in the cellar despite no evidence of leaks. Initially a chap from Homeserve came and replaced a stretch within the property boundary, but he reckoned there was a further leak out in the back street and handed it over to Yorkshire water who came and replaced some pipe out there the next day. The noise is now gone, however some days later we have an interesting problem.

Often when a cold tap has been used and turned off, or the WC cistern stops filling, a pulsing noise starts in the water main, it's most audible in the cellar but the vibration carries it up to the bathroom on the first floor. We find the noise can be stopped by turning a HOT tap on briefly, why is this? We have a combi boiler which is also in the cellar close to the main stoptap. Is this pulsing issue likely due to a further problem with the underground supply pipe, or potentially something to do with the boiler e.g flow switch? There is still no evidence of leaks internally.

Thanks in advance!

 

[CBW]

Sounds like it could be water hammer as a result of the pipe being fixed. Is all pipework securely clipped?

 

[Mattenstein]

As far as I know all the pipework is securely clipped yes. We've only had issues with water hammer when the combi was first installed and the DHW pipework was getting used to the high pressure, and the pressure has always been quite high.
Would it be normal for water hammer to continue indefinitely though? I thought it was always brief, this noise doesn't stop unless, as I said, you run a hot tap briefly. Why a hot tap I don't know, unless the water hammer is within the DWH pipes as before. It does tend to be a cold outlet that causes the noise to come back though.

 

[CBW]

No water hammer doesn’t continue indefinitely. Any dripping taps?

 

[Mattenstein]

Nope, no dripping anywhere that I can see

 

[denso13]

Any idea what the water pressure actually is? It will probably be higher than before the pipework was fixed, which can be problematic.

 

[Mattenstein]

Nope, but it doesnt seem any higher