Over flowing header tank

[Fallout]

Whats the best way of telling if this is a pin holed coil or fill valve not shutting off. Thanks. Imagine just check if the fill valve is shutting off.

 

[Nige F]

that's correct

 

[Fallout]

Thanks it's been doing it a while slowly. If was a pin holed coiled. Do these usually get worse over time or stay consistent? Thanks

 

[dilalio]

Isolate supply to fill valve.
If it doesn't have one, put one in.

 

[oldbuffer]

Three possible reasons for central heating header tank overflowing:
1. Fill valve not shutting off. Per. dilalio above.
2. Central heating pumping over. Could be various causes, including blocked system feed, pump on wrong setting. Tie an empty jar under the vent and see if it gets water in it when heating comes on / goes off.
3. Pin holed heating coil in hot water cylinder and central heating header tank lower than cold water storage cistern.

 

[Fallout]

Thanks has anyone every been to one were you had both a faulty ball valve. And a split coil. I.e changed the fill valve and the problem carried on. Is there a way of testing the coil. I imagine only if there is isolation valves on the flow and return to the cylinder coil. These could be isolated to see if this stops the problem.

 

[Madrab]

I imagine only if there is isolation valves on the flow and return to the cylinder coil

Isolate the CWSC's feed to the cylinder. If the F&E stops overflowing then chances are the coil's pinholed.

That's why the main CWSC cistern is/should always be mounted higher than the F&E, so in the worst case and the cylinder coil pinholes then the large cistern will always flow into the CH system through the coil and up into the F&E and not the other way about. That avoids the CH system water backflowing out the coil and contaminating the HW system.