Below is a guide to help you. If there is any question, ALWAYS buy the next size larger. It is always better to have more than enough heat, than not enough! Again, all items above are based on a 12" length and 1" ports.
A. 10 plates are used for domestic hot water or small in-floor heating
applications of less than 1100 sq ft. These will work with the largest of
domestic hot water systems and should never need to be larger unless you
use your domestic hot water for more than 3 hours straight at one time.
B. 20 Plates are used for smaller homes from 1100 - 2500 sq ft.
C. 40 Plates are used for larger homes from 2500 - 4500 sq. ft.
D. 70 Plates are used for areas 5000 - 7000 sq ft.
