How to calculate heating system capacity for expansion tank

[egizz983]

Hello want to know on how do you calculate size of expansion tank for closed heating systems . for example 500 meters of 16mm underfloor heating and 4 double ~1000mm radiators , hot water cylinder coil , and oil boiler

 

[ShaunCorbs]

Work out how many litres are in the ufh pipe the manufacturer should have 1m of 16mm pipe holds x amount of water

Rads 1l per rad

1 L for your cylinder and boiler

 

[John.g]

I think 16mm UFH pipe is 12mm ID so 500M = 56L, boiler+cyl coil, 30L, 4 rads, 40L, total 131L plus 10% for the cat = 144L, suggest a 15L EV or nearest.