My combination boiler drops pressure. I have been told that another expansion tank, fitted externally next to the boiler, will do the job. I am OK with the water side of plumbing but would like some advice on how to do this please.
hi kinstowan if you have pressure drop on boiler then you have a leak in the system or pressure vessel, adding another p/vessel in addition to existing should not be needed if the system has worked in the past.
check existing p/vessel is not full of water on the gas side it has schrader valve on gas side if you depress this and water comes out its knackered. if air comes out it may need recharging recharge to 1/2 bar all the best john