I have a Worcester Greenstar 24i/28i junior combi system. Water is pouring from the overflow and dripping from underneath the unit. Its snowing outside, the temperature is due to drop to about -5 within the next few hours and I have no heating or hot water. Can't get hold of a heating engineer, any idea what is wrong or what I can do until I can get someone out?
Oh, and I can't find anything to turn off the water feed to the boiler

Jax, January 2010

I have a vailliant convector boiler, I drained the system to remove radiator, when I topped it up and turned it back on water started leaking from it. Any suggestions please

George, August 2014

The temperature outside has prob frozen the water in the outlet plastic pipe, I have the same problem today, just used my gfs hairdryer to warm the pipe and wrapped a warm towl round the outsdie where the pipe leaves the house and enters a downpipe - the bolier is now working but i will get someone in to see if they can do anything else

Dave, January 2010