Central Heating Header Tank Dripping

[wade74]

Over the last few days we've noticed an issue with the central heating header tank dripping via the overflow pipe outside sometimes.

Having been up and examined the tank a few times, the water level is consistently at the level of the bottom of the overflow pipe.

Not knowing too much about these things, the ball cock seems a strange shape to me, curves downward into the water quite significantly, then an inch or so from the end just goes almost vertically down. This doesn't seem right...

Having investigated these forums, fixes seem to range from bending the ballcock arm (which a previous owner must have done before me i think!), replacing the ballcock, and then various other things.

Guess what i'm after is an indicator if changing the ballcock - which i'm planning on doing at the weekend - is likely to work, or maybe even make it worse

Water in the tank seems the right ambient temperature, though theres quite a bit of white gunk floating about on the surface (which can't be ideal)

Only noticed this a few days agio - may have been a problem for a while i guess. Noticed a major stream of water coming out of it on Saturday morning about 4am, after a dripping Mid Position Valve had leaked onto the pump, and caused an earth leakage which took tripped the consumer unit. Not sure what caused the overflow stream that morning, guess something backed back into the header tank when it all shutdown or something. Since replaced the Mid Pos Valve, and everything else (other than this drip) seems ok, but like i say it may well have been an issue for a while...

All advice very welcomed!

 

[JohnD]

first:

tell occupants not to run taps or flush toilets while you test

turn the boiler on (prefeably heating the cylinder as well as the rads)

turn off the main stopcock to the property

go up to the loft with a jug and bucket

mark the water level in the large cold water tank that feeds the bath taps

bale out the F&E into your bucket and mark the water level

sit up there and read the paper. observe if the water level rises. look at the ballcock to see if it is dripping, or if you can detect any water movement in the F&E, is it coming from the bottom?.

if the F&E level rises and the ballcock is not dripping, go and look in the big tank. Has the level dropped? by the amount of water that has appeared in the F&E?