hi dont know if any one can help got old glow worm boiler had pump replaced 2 weeks ago last week had heating eng in to replace diverter valve after 3 days and 4 leaks from loft heating and water still not working. Drained system and shut off water to tank only to find tank half full following day (confusing) repeated with same result, after racking brain was wondering if a leak in the heating pipe in the systern could cause this. have now drained systern to see if tank fills again. any ideas? very chilled 47.
If you are saying that you drained the primary system and its header tank and this has refilled then the most likely cause is that the hot water cylinder coil has perforated.
Turn your mains water off and see if the system refills and the water in your main water tank falls. If this happens get a plumber in to confirm.