Iâ??ve got a problem with water hammer on the kitchen cold tap. The noise is horrendous. Can anyone point me in the direction of a good cure. On the advice of a friend I drained the system with the stop c*ck closed and reopened the bottom tap with the stop c*ck still closed to drain off any air. Then re-opened the system and this worked for about 20 minutes when the noise returned.
Any advise much appreciated. pfj
Do you have a way to turn the actual flow rate down before the part where the hammering happens? I I remember when we had an increase in pressure here on top of a hill it would hammer if certain taps were used. A mere tweak on the stopcock where it comes in from outside seemed to fix it. Brian
I fitted one of these damped pistons right after the internal stopcock
It stopped all hammer from e.g washing machines and taps within my house, though occasionally a single thud from somewhere in the street will enter and make itself heard from my pipes.
They sell a 3/4" inch rather than 1/2" version which presumably has more capacity to absorb the hammer ...
Actually looking closer, the difference seems to be that it's easier to fit inline with a 3/4" washing-machine hose, and is probably only the same size piston/cylinder.
The usual advice is to close the stop-c*ck bit by bit until you no longer get hammer, but paradoxically, I found that opening it up also worked. But I'd try closing it first. Another cause can be 'bouncing' of the ball c*ck float in the water tank. That can be cured by fixing a damper to the float, simply a flat horizontal plastic or metal disk that sits below the water surface and resists rapid oscillations. Or fit one of these
More advice here
Learn not to turn that tap off so quickly.
If there is an isolator valve in the feed to that tap, try closing it a little to reduce the flow rate. Thus the velocity of the water in the pipe that is being brought to a sudden stop by the tap being closed too quickly.
You could fit one of those hammer arrestor devices but that really only treats the symptom, by providing a cushion of trapped air to absorb the momentum of the moving water, rather than being a cure.
I suspect that your mains water pressure is quite high. Can you open a mains fed cold tap quickly to fairly fully open without the water bouncing staight out of the basin/sink all over you? A PRV (Pressure Reducing Valve) in the rising main will stop the hammer and remove the caution required when opening a mains fed tap.
We had hammer here and rather "vicious" flow rates with incoming mains pressure around 4 to 5 Bar. Fitted a PRV, set that to 2.5 Bar, no hammer and "safe" taps. B-) If you do fit one and if you have any loft tanks make sure you don't reduce the pressure below that required for the water to reach the tanks.
Could it be the washing machine hose being too flexible? I get hammer if I leave my hose pipe turned on at the tap but off at the far end - sames sort of thing I guess.Sets up a rhythm
pete explained :
A cheap fix couple of feet of vertical pipe with the top end capped, connected to the problem pipe via a T, will help reduce hammer. The pipe will be full of air, which will act as a cushion, giving the rapidly flowing water some space to slow down into, helping avoiding the sudden rapid stop as a tap is turned off.
DerbyBorn submitted this idea :
I would not have thought - the hose pipe will expand to allow the water to slow down more gently. Its the sudden hard off, which causes hammer. Water rushing through rigid pipe, you suddenly shut off the outlet and the inertia of the rushing water has no where to go.
The other problem is vibration when water does flow, which is usually the tap washer at fault, setting up a vibration like the reed in a wind instrument.
n cold tap. The
fixes: replace the rubber washer in the offending tap/cistern turn a valve down, reducing flow rate. Fix the pipe to the wall better or add damping material - mildly effective Add a tee & an upright bit of capped off pipe.
NT
+1
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