Yes, have now identified lack of circulation as the problem and this seems to be caused by a dodgy pump.
With the power on, I removed the screw on the pump and manually turned the shaft. It was free to rotate and at first nothing happened but I kept turning it and then if fired into life and...
My system .....
Glow Worm Micron 50FF Boiler
Honeywell Programmable Timer (Heating & Hot Water programmed independently)
Honeywell Room Stat
Grundfos UPS 15-50 Water Pump
3-Way Motorised Valve
Here's my problem.....
When called upon by either heating / hot water or a combination...