Dripping overflow

[melodymaker]

The header tank's (above the emersion tank) overflow pipe is dripping water, even though the inlet seems to be closed off. Sometimes it does trickle water (I can hear it slightly) when the ballcock is fully risen but sometimes if I move the ballcock around it closes and isn't a problem (silent). It seems to be intermitent. Could it be a valve inside the water inlet or a washer? Can you get replacement inlets?

This is a frustrating problem I can never seem to get to the bottom of.

 

[grib]

You can take the ballcock apart and repair them but the're so cheap you might as well just buy a new one and be done with it.

Once fitted make sure the tank level isn't too high ( only needs to be a bit above the outlet at the bottom) If it's too full the tank will still overflow when the system heats up (water expands when hot).

If the tank still fills with a new and properly adjusted ballcok you could have a leak it the indirect coil in the cylinder, in which case best call a plumber.

 

[melodymaker]

Thanks but the water doesn't heat up in the plastic header tank as its cold.

 

[TicklyT]

When you say 'header tank', are you talking about the Cold Water Storage Tank, or a central heating feed and expansion tank?

A F&E tank (header tank)should only have a couple of inches of water covering the outlet.

A CWST is usually filled to a couple of inches below the overflow. A leaking ball valve is often masked by daily water usage keeping the water level below the overflow.

Both tanks need room for expansion. The water in a hot cylinder expands as it warms up, and some will flow back up the inlet to the CWST. As it comes from the bottom of the cylinder it is cold. The water in a heating system expands as the boiler heats it up, again, the difference is absorbed by the F&E tank. If it didn't the cylinder or boiler would burst.

Sometimes a worn float valve can appear to work fine during the day, but fail at night as the mains water pressure creeps up when water consumption drops.

Hot water in a CWST is a symptom of other plumbing problems probably not relevant here from your description of the problem.