Similar question to one already posted. My system is vented indirect, and although the radiators are getting hot, the water in my HW Clinder is not. I can feel the pipe from the boiler at the entrance to the cylinder is hot, but the return pipe at the bottom of the cylinder is cold. This makes me think an air lock or similar is present in the coil within the cylinder, is this possible, and how do I eleminate it??

Michael Riordan, December 2006

sounds like a air lock put on water only and turn pump on full speed.

hi-spec plumbing, December 2006

Yes, I have two seperate valves...one for heating and one for HW. Both appear to operate, the rads get hot and the i/p to the cylinder is hot.

Michael Riordan, December 2006

is the mid position valve working ok /zone valve

hi-spec plumbing, December 2006