Tekmar tN2 House Cntrl -Boil, SP, DHW, 4 Z-Vlvs. tekmarNet??2 House Control 400 is designed to operate all of mechanical equipment in a residential hydronic heating system, coordinating ir operation with network communication. It can be used in applications ranging from a single zone of baseboard with an on/off boiler, to multiple radiant floor zones with a modulating/condensing boiler. This control regulates one space heating water temperature through Outdoor Temperature Reset and Indoor Temperature Feedback. It is capable of controlling a single on/off, two stage, or modulating boiler, Domestic Hot Water, setpoint loads, 4 on-board zone valves, and can expand up to 24 zones in total.