Hi, I am experiencing a leak from my Worcester Bosch 28i Boiler. Upon inspection the leak is coming from the Auto Air Valve. I am not a plumber so I won't be trying to repair it, I am just trying to find some information about what caused the leak. The Boiler has been fitted for about 2 years and every now and again I had to top up the pressure from the filling loop. The Central heating hasn't been used in a while but the Hot water is used daily. I notice today that the Pressure is at 0 and the boiler is leaking. I have taken off the covers to find the cause and I can see water is dripping from the Air release valve - must have been a little while as there is a residue around the area. I have left a phone message with my plumber, but don't expect a return call until monday. I have also contacted Worcester Bosch and they have quoted £175 for replacement (standard Fixed Charge). I asked about the price of the part but as I am not an engineer/Installer they would not tell me. So, could anyone give me some more info on the Auto Air Valve, what could have caused the leak and approx how much they cost for the part. I would like to know a little more information on the problem if possible. Thanks in advance. Edit - I managed to talk to a mate who is a Ex plumber and he has given me some info. It seems that limescale has built up around the valve part and this caused the jam. Once jammed whilst open the water ebbs out from the top. He was quite surprised that the Valve would have that extent of Scale in two years, but he says that it can happen. Changing the valve is the best option as repairs to them are quick fixes. He has suggested tapping the side of the valve a few times to see if it will release the ball within the valve (which has jammed). Just done that and it works - leak fixed. My mate says that this is only a quick fix and it would be best to replace the part to save any more hassle. I am happy with that but if anyone has an idea on - cost of part approx and some more info on how it happened, please let me know.