Leaky coil in Hot water cylinder?

[Andy Champ]

I have a standard gas boiler heating the hot water and radiators. The hot water cylinder has an indirect coil.

There's a cold water tank and a seperate header tank for the rads/coil in the loft. The base of the two tanks is level, so the water in the header tank is a couple of feet below the main tank.

I've been suffering problems with the overflow from the header tank dripping. So I changed the rubber washer. Then the fibre washer. Then I turned off the stop c*ck. Now I've actually disconnected the feed into the ball valve from the tank - and *STILL* it drips. The only thing I can think of left that could be causing the problem is a leak in the coil in the cylinder. Before I go out and spend 200 squid on a new tank and spend a weekend pulling the darn thing apart, is there anything easier/cheaper that could be causing it?

Ta

Andy

[EricP]

Leave the mains turned off and bail out some water to reduce the level to three inches below the overflow.

Watch it each day to see if it keeps rising to overflow again. If it does, your reasoning on the problem seems sound..

[Doctor Drivel]

Is there a way of isolating the coil? Leave CH off so zone valve is closed and close up a lockshield gate valve on the coil return (if one there). Even though the gate valve may be closed it may pass water.

You have fully isolated the cold water into the F&E tank. The symptoms are that of a leaking coil.

As you are having some major work, you may want to improve the system. Replace the cylinder with a heat bank sylinder (thermal store) giving mains water pressure at all the taps and showers. It does away with the two tanks in the loft. The heat bank could go in the loft out of the way where the old cold water tank was, liberating space in the house. The system would be vastly improved and well worth doing.