The kit 38G.14.DN25 is composed of a heat exchanger, complete with fill/drain cock and safety group, and a direct distribution group on the secondary side. The kit 02C.10 is composed of the only heat exchanger, complete with fill/drain cock and safety group, and the fittings necessary for the primary and secondary side connection. The kits with heat exchanger can be used in several system types, as for example biomass, solar, heating. They can be installed to separate circuits with different fluids (i.e. with/without glycol), to avoid dirt from entering the circuit of a new generator, to couple an open vessel primary circuit to a closed vessel secondary circuit or to avoid the sum of the power outputs of two generators supplying the same system (according to the Italian standard). The kit with heat exchanger 02C.10 is complete with fittings for distribution group connection. The safety relief valve and the expansion vessel connection should be considered as the basic safety requirement for the system connected on the secondary side of the heat exchanger.