Is this water hammer?

Hi

For the last couple of nights there has been this banging or shuffling noise coming from behind our wall in the front room where the pipes lead from the back boiler up to the hot water tank. The noise lasts about five seconds and I thought initially it was the neighbour or some rodent activity (it's not).

There is no noise during the day or throughout the night although I can't be sure as our bedroom is not above the front room. The noise happens approximately 1.5 hours after the hot water and GCH is OFF. It is not connected to any use of taps, toilets, washing machine etc as we were not using them at the time. It seems to happen when nothing is going on I.e. the system is off, it is late evening, and we are sitting down.

We have been in the house for 18 months and there has been no noise until this week. No work has been undertaken on the system aside from a new pump and pipe (between cold water and hot water tank) three months ago as we had a blocked pipe.

Can anyone advise me what this is and why this is happening when there is no activity? Also is this something I have to get fixed soon? Thanks

Water hammer happens when a tap - previously running - is turned off. The resulting pulse of pressure causes the pipe to move, and collide with something nearby. The solution is to ensure that the pipes are well clipped to solid material at regular intervals.
Personally I think that your noise is an air bubble, escaping from your back boiler and working its way back up to the loft header tank.....as the boiler switches off and the pump stops residual heat can build up and cause this.
Check that the loft header tank has about 4" of water in it, as a start. Can you hear any air rushing through the radiators when the heating is on?
I do have a feeling that there could be a considerable amount of gunge in your system....
John

Burnerman said:

I do have a feeling that there could be a considerable amount of gunge in your system....
John

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With that diagnostic ability you should be a colonic irrigationist

Only with the curtains shut mate
John