Water-hammer keeps reoccuring

digisatman

digisatman

digisatman

Associate
Joined
8 Oct 2006
Posts
1,236
Hi all,

Just wanted a bit of advice, I have a unvented system boiler I think, and basically for the last couple of weeks whenever I turn the hot water tap (upstairs or downstairs) I get the "Water Hammer Noise" of the pipes vibrating when I close the hot water tap.

I turned the water supply off, let the water/air drain out and then turn supply back on, this fixes the problem for about a day and a half before it starts again.

Anyone have any ideas whats up?
 
Can I just confirm that this happens equally with every hot tap? If so, have you managed to pin down the noise to a particular area? Could be either a tap washer or maybe some copper pipes have come loose.
 
It might do it if the pipes are loose in the wall and there won't be much you can do about it. There are inline dampers that you can fit, like a little spring in a cylinder that takes out the hammer effect. Might work?
 
Do you have any valves around the tank? if you do you could try winding them all the way in and out, could be a build up scale around them.

Are you sure the it's not the boiler loop? is it a combi?
 
Well it started upstairs in bathroom, but now it happens in the kitchen downstairs as well. The kitchen had its taps replaced last year so I don't think its the washer, and the fact that the problem goes away for a day or 2 once I drain the system leads me to beleive its something else? The noise seems to come from the cupboard where the hot water tank is.
 
Jonny69 said:
It might do it if the pipes are loose in the wall and there won't be much you can do about it. There are inline dampers that you can fit, like a little spring in a cylinder that takes out the hammer effect. Might work?
Click to expand...
He might already have one of these and it could be filling up with water, hence it going away when he drains the system.

OP needs to confirm the presence of a damper or not (looks like some kind of vertical tube, probably near a valve)
 
Sounds like you need a new cylinder or get an external dhw expansion vessel. Draining and refilling the cylinder recharges the expansion pocket in your cylinder, hence it working for a couple of days. If it can't keep that pocket of air any longer then it's had it.

Might be worth checking with the cylinder manufacturer as many have 20yr warranty.

Mick
 
If its a heatrae megaflo they have an internal air-gap any other make of cylinder has a seperate expansion vessel if they are mains fed,
sounds like a pressure issue rather than a washer tbh all unvented cylinders have a coldwater control valve basicly a pressure reducer and a pressure relief, i would get someone in that is qualified to check unvented systems.
 
I suspect that pressure reducing valves or pressure release valves need cleaning, replacing, had exactly the same problem with a megaflow in my previous place.

My cylinder was serviced every year along with the boiler.
 
You must log in or register to reply here.
Back
Top Bottom