Boiler Sizing

[Paulhar]

Hi All,
I'm trying to work out a boiler size for a huge, four storey victorian property, part of which is already heated. I'll be adding a second boiler, 18 rads and a cylinder. Is there a heat loss calculator online somewhere or can I relate the boiler size to the total kw output of all the rads (approx 28kW) ?
Any help much appreciated.

 

[SJB060685]

Try heatengineer.com.
Alternatively there are other quick guides.