I have a 28cdi and when you run the hot tap the water gets hotter and hotter until the pilot cuts out. After a short while it fires up again and this repeats.Also this happens on central heating demand and radiators don't have a chance to get warm. It looks like a circulation problem but the pump seems ok.Where should I look?

Den, May 2009

Check the Auto Air Vent on top of the Boiler is working, the black plastic screw should be loose by about 2 turns, the AAV may need repalcing

www.elanar.co.uk, May 2009