Water hammer at same time every night

[Mr Gwent]

I wonder can anyone give me some advice over what has become a very annoying situation?

Approximately three months ago, what I assume to be water hammer started in the airing cupboard of my second floor flat. This manifested, and continues to do so, as a repeated, i.e. every 60 seconds or so, banging or knocking as if the pipes are moving or coughing,

The sound seems to occur primarily during the late evenings and at the night, usually between 01 00 - 04 30 hrs, although I have heard it during the day as well. The sound is also rather loud at approximately 50 decibels.

A plumber was unable to identify the specific cause of the problem but did determine that the stopcock was defective. However, this does not affect the water supply to, and within, my flat.

So, can anyone advise:

• Can a defective stopcock cause repeated water hammer?
• Why such water hammer frequently happens at the times described above?
• What can / should be done about this?

Thanks

Mr Gwent.

 

[Last Plumber]

Water hammer can be caused by a number of things but normally water will be flowing when it occurs.

Yes a faulty stop tap (with a loose jumper) can cause it but that would usually be when water is flowing through it and stops flowing e.g. on closing a tap further down the supply.

If the flats are fed by a tank/storage system then it could be the ball tap opening and closing (maybe oscillating if this sounds continuous over time).

Water pressure is generally higher through the night (off peak) and this can mean that water hammer is more likely to occur.

Is the block of flats tank fed?
Have you mentioned it to maintenance (if there is such a thing)?
Could it be other residents who are up and about during the night using the water when the pressure is higher?

There are things that can be done to cure it but you would normally need to identify the cause first.

 

[Mr Gwent]

@Last Plumber

Thanks for your reply. I am not aware of any of the other flats having a problem of the kind I have described. In any case, each flat in my block has its own water tank and hot water cylinder.

Sometimes, my flat's stopcock does cough if water is used in another flat, but that does not explain the frequent noise at night. However, when the noise does occur, a vibration in the pipe above the stopcock can be felt.

Mr Gwent.

 

[Last Plumber]

@Last Plumber

Thanks for your reply. I am not aware of any of the other flats having a problem of the kind I have described. In any case, each flat in my block has its own water tank and hot water cylinder.

Sometimes, my flat's stopcock does cough if water is used in another flat, but that does not explain the frequent noise at night. However, when the noise does occur, a vibration in the pipe above the stopcock can be felt.

Mr Gwent.

Try turning the water to the stopcock off at night to see if that makes a difference. If it does it may need to be replaced.

 

[Mr Gwent]

@Last Plumber

That's part of the problem, i.e. the handle on the stopcock won't budge!

Mr Gwent.

 

[Ric2013]

Are we sure it's water hammer and not expansion and contraction on a heating pipe rubbing against something? Assuming, of course, there is any heating switched on at that time of night (as is the modern trend).

 

[Mr Gwent]

@Ric2013

No. It could be possibly expansion and contraction but not of a heating pipe. My flat's heating is entirely electric.

Thanks

Mr Gwent.

 

[rpm]

Water pressure can rise at night through little use causing it to do werid things.

 

[Knappers]

First thing I do with that kind of noise is replace all the diaphragms in toilets and float valves no matter how remote from the noise.
Can sometimes be tap valves too

 

[Last Plumber]

@Last Plumber

That's part of the problem, i.e. the handle on the stopcock won't budge!

Mr Gwent.

If you are not DIY competent in the matter, you should perhaps get a Plumber in to sort the stopcock and whilst they're at it, replace the ball valve. For the small amount they cost it is worth swapping it to rule it out if you are going to pay for the services of a pro.