Water Hammer

[Bob Minchin]

Having added an extra cold water pipe run in our utility room, there is a tendency for water hammer elsewhere in the system if taps are turned off with enthusiasm (about the only enthusiasm my son shows about anything!)

I have seen this product

in the toolstation catalogue and wonder if it is critical whereabouts in the system it is installed. I can see an argument for it to be on the rising main after the meter before any branches off to taps etc but on the other hand could it be almost anywhere as all the pipes are hydraulically linked?

Presumably there is a diaphragm and damped spring arrangement inside?

TIA

Bob

[A.Lee]

I've got the same problem, whenever the neighbours turn a tap off quickly, I get a bang on my pipes. That fitting looks good. I'd have it aroudn 3 feet above the stop tap in my house, that is where the pipes bang, so hopefully that shoudl cure it. Alan.

[RubberBiker]

The root causes of water hammer can also be poorly clipped-down pipes, and surface waves in water tanks causing ballcocks to cycle.

[The Medway Handyman]

Or a diaphragm with inert gas behind it. Using a flexible somewhere sometimes sorts out water hammer.

[Lobster]

We had a toilet cistern which despite having fitted a Torbeck valve still gave an almighty, house-wakening 'thunk' every time the valve closed off when the cistern refilled.

I bought the same shock arrestor to cure the problem, and fitted it to the cold water system at a convenient point. The whole house is on mains-pressure water, and I tapped into the pipework where it passes (surface-mounted) through a downstairs walk-in cupboard.

Sadly despite definiely being 'hydraulically linked' it made no difference whatsoever to the noise. I therefore resited the arrestor to a tee immediately below the cistern concerned; and it now does the job perfectly if being a little unslightly!

So - in answer to your query: I don't know how far away from the affected pipework you can fit it, but yes, the location is clearly pretty important. But I'm sure mine could have been further away (hidden) and still worked.

FYI I found the arrestor was surprisingly small versus what I was expecting - the white body is about 70mm diameter by 70mm high.

David

[Bob Minchin]

Thanks for the reply David.

My problem seems to be caused by the extra pipe run in the downstairs utility where it is tee'd off the rising main but the effect is triggered by several taps quite distant from the new pipes such as the upstairs bathroom. Looks like I will have to experiment. I do have one more change to make which will include a short length of flexi to a garden tap off this new pipe run. So maybe the problem will be solved by that change as per Dave

- AKA Medway Handyman's post in this thread.

Bob

[Lobster]

Heh. When I had to rejig the pipe configuration below my cistern in order to add in the arrestor, I installed a flexi there. So I wonder if just that would have cured the problem on its own! (I'm not sufficiently curious about that to test-de-install the arrestor now...)

David

[Dave Liquorice]

Did you fit the appropiate flow restrictor? There are three options none, LP and HP. Torbecks and similar valves are water pressure operated and if the flow is too high they do shut off from full flow

*very* quickly.

[PeterC]

Yes, that's true. I used the wrong one on a good supply and it did bang shut. I once inadvertently operated the flush just after turning on the shower and the bang smashed the inlet control on the shower - useful to have a valve just below the shower unit to give some control. Also, it filled so quickly that I had 4 li of 'padding' in the cistern to keep it down to about 8 li.

[Lobster]

Yep!

David

[NT]

fwiw

[Andy Dingley]

I once had to deal with a bathroom flood where our only surmise afterwards for the cause was that an unrestricted Torbeck like that had caused the the threaded valve cover to split and blow off the case, dumping the whole flow rate into the cistern (far faster than the overflow could cope).

[Dave Liquorice]

This is why the instructions (if you read 'em...) say to check that the overflow can cope. Though I suspect they don't mean when the cap has blown off just with the float held down or dropped off.