Pressure vessel sizing ???

[Nellya1970]

I am fitting a new Keston C55 boiler to an existing system that is open vented but customer want to remove the expansion tank and turn system to a sealed system.
The house has six double bedrooms and a snooker room,3 reception rooms and a massive kitchen, i have counted the rads and there is 27 of them mostly doubles.
I know its difficult to know the amount of water in the system but can anyone help with calculating the vessel size needed,the primaries to the system are 35mm and the 2 heating circuits are run in 28mm.
can anyone help ????

 

[gas4you]

I would have thought the Keston manual will give a table of different calculations for different sized systems.

But then it is a Keston

 

[corgiman]

I would have thought the Keston manual will give a table of different calculations for different sized systems.

But then it is a Keston

I agree why fit that POS??

 

[BingoBongo]

gas installer monthly had all the info on expansion vessel sizes about 2-3 months ago im sure

 

[doitall]

10% of the system volume, rads you can get of the manufactures charts, pipe volumes can be worked out if you get a rough length/size

As a guide 50-60 Ltrs expansion vessel will be close.