Right. Potterton boiler on an unvented system, midposition valve feeds HW and CH.
Boiler fires up, the valve opens correctly, pump starts spinning, but the hot water from the boiler (about 10 foot away) takes a good ten minutes to get to the pump.
Seems like the water and pipework is being heated by conduction, and not flowing round. The midposition valve works (A4073), changed the pump (Grundfos 15-60), took all the rads off the wall and flushed them out with a hosepipe (really nasty stuff in there!).
Any ideas? Please? Before I rip out the remaining hair on my head?
Boiler fires up, the valve opens correctly, pump starts spinning, but the hot water from the boiler (about 10 foot away) takes a good ten minutes to get to the pump.
Seems like the water and pipework is being heated by conduction, and not flowing round. The midposition valve works (A4073), changed the pump (Grundfos 15-60), took all the rads off the wall and flushed them out with a hosepipe (really nasty stuff in there!).
Any ideas? Please? Before I rip out the remaining hair on my head?
