warm water comeing out of over flow?

when the system is cold there should only be about 6" of water in the tank, if any higher, the ball valve arm should be adjusted, the tank baled out so that the 6" level is achieved, if water is nearly up to the overflow when cold, the tank WILL OVERFLOW when the boiler fires, this is because HOT WATER EXPANDS when heated, and the Feed & EXPANSION tank is where this expanded water is accomodated, (the clue is in the name feed & Expansion) Simples

P.S. Sounds like you have a Beta Sorrento boiler (later Heating World)

www.elanar.co.uk
May 2009

Are you talking about the curved copper pipe that exits just above the flow and expansion tank? If so, its called the expansion pipe, and will drip a small amount of water if your heating system(s) are producing more hot water than your house can cope with. Its a sort of a safety valve really and the drip can probably be stopped or reduced by turning your thermostat down on your boiler. Basically, you are producing too much heat!

John
May 2009