Expansion vessel sizing

[GasmanxxxR1]

I might be fitting a logic+ 18kw system boiler in a town house with newish single panel rads.

I was told years ago that system boilers etc with internal expansion tank are sized correctly for their output kw.

Anyone have a technique for getting this right.

I seem to remember calculating installation water volume at 6l/kw or some such then working it out from there.

 

[lame plumber]

wont need to bother where u are

 

[GasmanxxxR1]

wont need to bother where u are

i dont get it

 

[Ray Stafford]

I was taught it was 1/23rd of the volume of water in the system.

 

[lame plumber]

meaning its a mall house and single rads it isnt an issue to worry about, when you star wacking in 25 +rads, then get calculating, otherwise have a read of the instructions, its what they are there for.

 

[kay-jay]

kw? surely the pertinent factor here is volume of system. expansion needs to allow for 4% of volume then fit the next size up.

 

[EPH]

Advanced Water Company

 

[turnpin]

Altecnic vessels offer a free calculator for their vessels Tel.01785_218200 to request yours...regards Turnpin:smile5:

 

[Ermintrude]

Most Logic will do 80l easy. But I'm twitchy at 100l prefer smaller

 

[GasmanxxxR1]

with 15 rads over three floors im thinking it close to 100l, what do you think

maybe i should add an external vessel as well

 

[Ermintrude]

Only £30 better safe than stupid. 18l?

 

[kay-jay]

18l is mire than enough. As ermine says better safe than sorry fir a few quid

 

[EPH]

Looks borderline to me, best to err on the side of caution IMHO.