My HW works ok when no CH is on. and even when boiler is on low it still works and so does the pump, the zone valves close and open appropriately. Any other ideas, I have even switch off all rads then starting with the problem one switch them on. Gradually the 1st rad starts to diminish if...
It's a boiler fitted in 1986 by prev. owner boiler type is a Glow-worm fuelsaver 'F', 8 rads are fed from it aswell as tap hot water. the boiler stat has a range of 1-5, if I try and turn up boiler stat from it's current setting of 2 upto 3+ then the rads start to go cold and tap hot water heat...