Central heating being filled by cold water

[glennc67]

Hi

i have been having an issue with not getting any hot water, checked the cylinder and found that the inlet to the coil was hot but the return was cold (so assumed a blockage in the coil)

Whilst attempted to drain down the CH system noticed that the cold water header was constantly refilling and the F and E tank was not emptying at all.

Isolated the cold water feed to the cylinder and the F and E tank stated to empty until the system was fully drained. To try and understand what was happening i than opened the cold water feed to the cylinder and water started running from the radiator drain again (F and E tank still isolated).

Unless i am missing something ( which is not unusual lol) does this mean i have a leak in the cylinder coil?

Thanks for looking

 

[danplumb]

You maybe right in that the coil may have split, this is why the CWSC should always be fitted higher to the F&E so the water in the cylinder should have slightly more pressure than that in the coil, so the clean cold water will fill into the coil rather than the dirty heating water from your coil filling into your hot water.