Potterton combi 80 boiler?

The expansion vessel is lacking in pressure here - often coloured red and sitting inside the boiler, it is a 2 chamber device with air on one side, water on the other, rubber diaphragm in between. There is a normal tyre valve connection for the air side and the average pressure for this is 10 psi. Check for water leaks around the central rim, too.

John
March 2008