Frequently overflowing header tank

[Nemo]

Hi Gang

A quick one for you... I have a header tank which discharges into the overflow pipe fairly frequently and not just a drip or two either.

I have adjusted the float and replaced the ballvalve, but still it does the same and I'm fairly certain that the extra water is not coming in from the supply side via the ballvalve...

Any thoughts?

Cheers
Nemo

 

[kevplumb]

which header tank ?

 

[ChrisR]

Probably either mains water getting into the HW system via a mixer tap which lets water across, or
water moving from heatng system to tap water system or vice versa through a leak in the coil of the HW cylinder.

 

[Nemo]

Thanks Chris - I had considered the possibility of a fault in the coil, but did not think to look for a problem with a mixer tap - duh! Much easier to check the tap than pressure test the coil....

Cheers
nemo

 

[bobb]

i had this problem and it was cold water at mains pressure passing through a shower mixer unit into the hot water system. a non return valve in the hot feed to the shower did the trick.