We drained our central heating system down, and now having apparently filled it up again the boiler is working the central heating (propelled by a pump) but not the hot water which is in a tank up in the loft. That should be heated indirectly from pipes from the boiler circulating water by convection. We think that there is probably an airlock at the top of this system, in the indirect pipe inside the tank,but don't know how to shift it. The boiler is a Glow-worm space saver, and keeps cutting out as it has heated the bit of water in the pipes going through it. Have drained the system before but not had this problem. Please can anyone help?

Failed plumber, October 2008

Hi Stevie, we did what you suggested and hey presto it works, brilliant - only a few tiles off the roof and I think the cat will come home when he's hungry. Seriously though, it didn't take much more than a few burps and gurgles, and its running fine now. Thanks very much indeed. Off to wash up now, didn't realise how much fun it is with hot water........

Successful plumber, October 2008

ok failed plumber your not going to like what im going to tell you but this is the only way to fix this

First locate the boiler thermostat phial and pull it out of the main heat exchanger sometimes held in place by a small screw through a small meatal disc,turn on the boiler to hot water only and let it heat up it will soon start to boil and you will hear loud noises like a hammer being hit off the copper pipes. by boiling the water you will push the airlock out of your gravity hot water pipes. it might boil for 10 secs or so then stop as the water starts to circulate again.this is the only way i should know i have 25 years as a gas technician with a huge gas company all the besty and dont be too frightned by the noise it wont do any harm. remember to replace the phial afterwards.

stevie w, October 2008