Formula:
2b+3m+HW
Hydrocollectors:
3G
(to see the description of a collector, click on the link)
Regulation:
634+MM1, XE90, HMC82

Two primary loops with a shared fragment. Suits best either for the systems with spare boilers, or for large (>80 kW) power systems with a small number of contours. Very compact in assembling.