Had to change a rad, so drained down compleat system, inadvertantly drained hot water as well!! refilled and bled rads, heating working fine but now there is no hot water!! (Baxi coal affect fire with back boiler for heating and hot water) if I demand hot water only the boiler fires up for aprox 30secs then switches off. There is some "gurgling" in the boiler pipes that run upstairs to the cylinder. If this is air, how do I remove it!!

Dave, March 2008

Is it a fully pumped system,? or is the heating of the hot water gravity fed,? you can check for this by looking in your cylinder cupboard and see if there is a zone valve. If not its likely to be gravity fed. If so the air can be vented by slackening off the connection of the upper most pipe(22mm) of the 2 pipes entering the side of the cylinder. Theese are the circulation pipes that heat the h/w inyour cylinder. Don't undo the nut completely and tap the pipe gently out of its housing, it will leak a little so have a towel handy. Do this while boiler is lit and on demmand for h/w,so its better if you have assistance who can lite the boiler while you do the venting. This is of course on the assumption its a gravity fed h/w system, and i mean the HEATING of the h/w is gravity fed. Good luck

Pete, March 2008

The other thing to check is that you have not closed the cyl balancing valve by accident(provided this is a fully pumped system)
This is located normally on the return pipe of the heating system.
most cyls have 4 pipes, the one on top is hw out, the lowest of the other 3 is cold in, and the balancing valve should be on the lowest of the remaining 2.

gary.wright53@googlemail.com, March 2008

look near cylinder for air vent or thumb screw

dpheating, March 2008