Expansion vessel

[MoCay1]

Hi

My boiler is in need of an expansion vessel. How do I work out what size and type is required?

I heard it is it the amount of water that is in the system times by 4?

If so I have worked out the length of pipes within the heating system and the radiator sizes. Not sure how to work out how much water is in the radiators.

Can anyone help?

 

[TCCHeating]

As a general rule. Allowing 1.5 litres per radiator should be more than sufficient. (This takes into account that some radiators will be small and some bigger). There is not a great deal of price difference between, say a 20l vessel and a 30l vessel so there is no harm in oversizing it. Space permitting of course!