hotwater overflow is dripping

10 May 2009
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United Kingdom
hi the overflow for hot water tank in loft is constantly dripping, i have checked the float valve and that seems to operate as it should so any ideas what it could be and how to fix this problem.
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The float valve could be set to high(worn in time), you could try bending the arm down a bit
Bigger problem if you have a sealed system or high level header tank could be a pinholed cylinder coil
hi the overflow for hot water tank in loft is constantly dripping
Just to confirm, you are talking about the smaller of the two tanks in the loft?

When the heating water is cold the level should be about 4cm above the lower output; the ball valve arm should be bent to set the level. It is important that the valve opens before the level drops to the top of the outlet pipe, otherwise air can enter the system. The level will rise as the water is heated, but should stop well below the overflow. If the level continues to rise, the coil in the hot water cylinder is probably split or holed.
after taking another look yes it is the smaller tank in loft (hot water) and the level is correct when cold, other info i found out today is that when hot water cylinder is on hot water comes up vent pipe and flows into tank but the level rises but does not overflow. but when vent water stops and cylinder is off the water in tank slowly rises and then overflows. do you still think this would be the coil
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shut the gate valve in the airing cupboard on the supply pipe to the bottom of the cylinder.
does it stop filling then ?
You are talking about the heating expansion tank, not the hot water cold storage tank.

Is the hot water storage tank higher than the expansion tank?

If so it could still point to a holed coil in the cylinder. Could be you also have a blockage in your heating system.

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