water hammer

[roy entwistleParticipant @royentwistle24699]

Gentlemen My hot water tap downstairs develops a squealing noise and the tap vibrates. The stop tap on the hot water is upstairs. Do I open the bottom tap and close the stoptap to empty the pipe, and then open the stoptap with the bottom tap open then close the bottom tap, or do I open the stoptap with the bottom tap closed  or what ?

Thanks in anticipation

Roy

Edited By roy entwistle on 12/02/2020 15:20:15

[roy entwistleParticipant @royentwistle24699]

[Joseph Noci 1Participant @josephnoci1]

Roy, do you know what sort of tap seal is used on the tap? A sliding ceramic thingy, or the old rubber/plastic 'tap-washer'? I had an outside tap do that – it was an old style with a tap washer, but the washer fitted to a fitting which was a 5mm diameter brass rod, maybe 20mm long, with a flat brass disc on the end – the washer sat against that flat disc. This assembly then slid, shaft first, into a hole in the part of the tap that screwed up and down to close – this little assembly would , when just right, rattle up and down as the water passed by – sort of blocking and un-blocking the path.

If your tap is more 'modern' probably not the problem – but the upper tap , if of the above style, could still cause the problem.

Joe

[SteviegtrParticipant @steviegtr]

I think you are assuming that there is air in the system. Not always the case. Sometimes it can be the shuttle in the tap rattling . My neighbour was forever hooking a piece of hose from the cold water tap onto the hot. Then opening the hot fully & then the cold. Effectively forcing mains pressure cold back up to the hot water tank. Like bleeding your brakes. Eventually he fitted a new tap & it never happened again.

You will find if you close the stop tap upstairs on the tank. You will get little water from your downstairs tap. As it just vacuum's up. Also it could introduce air in through the hot tap. Making things worse. Also is the pipe run clipped tight as a length of copper can start to oscillate if not held firm.

Steve.

[roy entwistleParticipant @royentwistle24699]

Gentlemen All my taps are old style tap with a plastic washer

[Paul LousickParticipant @paullousick59116]

It is not uncommon for metal pipes in a plumbing system to bang loudly when a faucet is shut off suddenly, or when a water-using appliance such as a washing machine or dishwasher shuts off the water intake abruptly. It is not normally caused by air in the pipes.

The condition is commonly known as water hammer. The technical term is hydraulic shock, and it occurs when water stops or changes directions suddenly. The banging you hear is caused by the shock wave that causes plumbing pipes to move and strike against one another or against wooden framing members. In addition to being annoying, water hammer can be so forceful that it can break pipes or loosen plumbing joints.

An explanation on Youtube shown here: **LINK**

Paul.

[Enough!Participant @enough]

On this side of the pond you can get these  from Home Depot et al. Presumably something similar is available in the UK. They did wonders for my washing machine …. might help in your situation

Edited By Bandersnatch on 12/02/2020 22:46:57

[not done it yetParticipant @notdoneityet]

Or you could try fitting a section of flexible pipe in the line, if that is the source of the vibration? Presumably this is a vented hot water supply?

[Mike PooleParticipant @mikepoole82104]

I have had water hammer and it has been caused by a faulty valve, in my case a Torbeck type ball cock. I have had no trouble since I replaced it.

Mike

[Paul LousickParticipant @paullousick59116]

We even put one of the hammer arresters on the outlet pipe of the pump on our traction engine to soften the thumping action of the piston. Made it a lot quieter.

Another option is to use an anti-hammer tap washer. These are spring loaded and close more slowly.  Other types are available from plumbing and hardware stores.

Paul

Edited By Paul Lousick on 13/02/2020 00:22:47

[SteviegtrParticipant @steviegtr]

Posted by Mike Poole on 13/02/2020 00:13:54:

I have had water hammer and it has been caused by a faulty valve, in my case a Torbeck type ball cock. I have had no trouble since I replaced it.

Mike

Had this a few times too. The old brass ball cocks were terrible for it.

Steve.

[Martin ConnellyParticipant @martinconnelly55370]

I have had to put in accumulators, similar to the one Bandersnatch referred to, into two different houses.

Martin C

[SillyOldDufferModerator @sillyoldduffer]

As Roy describes squealing rather than a single thump, this fault suggests oscillation. Possibilities include a bouncy ball-cock or other valve, and either long unsupported pipe runs or air in the system acting as a spring (air is more likely). Or all of the above in concert!

I get squeal after every home plumbing adventure. In my case bleeding air by running all the taps flat out (one at a time) works eventually. It can take a few minutes flow to get a reassuring cough-splutter as the air ejects, and once in a blue moon I've had to repeat the whole process.

Changing a tap washer in my Utility Room causes more trouble than fixing a Bathroom tap upstairs. I guess it's to do with where my home's particular pipe layout allows air to collect. I start by running downstairs taps and work up. There's no science in it, other than me assuming air bubbles tend to rise. Experiment.

A friend back-flushed his system to fix a bad case of howling and knocking, and he also added a foamy potion to his central heating to stop a radiator banging. My dad's house had an old-fashioned tank in the loft (now considered bad-practice), and he fixed his shrieking by fitting a new washer to the ball cock and bending the arm down.

Dave

[SteviegtrParticipant @steviegtr]

I recently re-plumbed the whole house & fitted a new Combi Baxi boiler. One thing I did learn a long time ago is you cannot have enough stop taps. It makes for easy repairs to the outlets.

Steve.

[Jeff DaymanParticipant @jeffdayman43397]

Here's a special tool for hard water hammer.

**LINK**

[duncan webster 1Participant @duncanwebster1]

Posted by Steviegtr on 13/02/2020 19:22:35:

I recently re-plumbed the whole house & fitted a new Combi Baxi boiler. One thing I did learn a long time ago is you cannot have enough stop taps. It makes for easy repairs to the outlets.

Steve.

It's a good idea to go round and fully close/open all stoptaps every couple of years, otherwise when you need to close one you'll find it seized. Don't ask how I know. When you've fully opened it, just close it ever so slightly so it's not against the stop.

On the squealing tap issue, I'm wit Steviegitur above, suspect the tap. Try fitting a new washer.

[Enough!Participant @enough]

Posted by duncan webster on 13/02/2020 21:33:05:

It's a good idea to go round and fully close/open all stoptaps every couple of years, otherwise when you need to close one you'll find it seized. Don't ask how I know. When you've fully opened it, just close it ever so slightly so it's not against the stop.

+1

Moreover, if you don't operate it for a few years, and even if it isn't seized, it will likely leak at the stem when you do.

[roy entwistleParticipant @royentwistle24699]

Gentlemen I let the hot water run for about 1/4 hour the noise stopped after a couple of minutes there was a lot of spluttering and it seems to be OK now. Time will tell but thanks for your suggestions

Roy

[SteviegtrParticipant @steviegtr]

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