Hi, no doubt this question has been asked before, but I find myself perplexed.
Our CH/HW set up is:
1.Boiler (old but still perfectly functioning) located in kitchen on ground floor.
2. HW cylinder located in airing cupboard on first floor.
3. Cold water storage and CH F&E tanks located in loft, side by side on plinth above the HW cylinder.
A few months back the pump was replaced, burnt out due to the pipe being clogged with gunk and over pumping. Since then the system has been power flushed to clear it out.
This has cleared the system and the over pumping has ceased, no more scalding water going into the F&E tank.
However, before the system was flushed, cold water was flowing into the F&E tank and overflowing. This has continued, requiring frequent bailouts, and this only occurs when the boiler is not running and the system is cold.
In short:
1.The system is not over pumping, the water flowing into the tank is cold not hot, no water is entering via the vent pipe.
2.The float valve has been replaced with a new one, and the level set so that the tank will hold around 6" of water. This is fed from an outlet pipe from the cold water storage tank.
3.All rads have been bled.
And yet cold water is still flowing into the tank, researching this I think that I may be faced with a pinhole in the HW cylinder coil, yet there does not appear to be any cross contamination between the CH water and the domestic HW.
Any ideas or clarification will be gratefully received, as I am totally stumped.
