Under - Boiler units distribution systems USE The UNDER-BOILER UNITS with built-in installation, which can deliver the right flow and proper head to the thermo-carrier fluid in domestic hydraulic systems with wallmounted boilers. They can be configured during the ordering process, up to a maximum of 3 zones: • direct zone: high temperature • mixing fixed-point zone: with thermostatic valve, adjustable between 30°C and 60°C • mixing modulating zone: with control unit and weather compensation The under-boiler units have a multifunction manifold with integrated hydraulic separator, high efficiency pumps, flow and return thermometers, interception valves on the plant and boiler sides, non-return valve and insulation. They are also equipped with an electric box to manage the zones and control the boiler. KEY FEATURES • Built-in hydraulic compensator • Ultra compact size • Simplified hydraulic connections • Electromechanical control unit • Easy installation for zone management and boiler activation APPLICATION EXAMPLE Under-boiler unit High temperature heating system Radiant panel system External temperature probe for weather compensation Room thermostat

Under - Boiler Units VERSION AND CODE BUILDER OVERALL SIZE EXAMPLE • ST3MHD code: 3-zone under-boiler unit with mixing modulating left-hand zone, mixing fixed-point central zone and direct right-hand zone MODEL ST2 = 2 zones ST3 = 3 zones ZONE 1 type • LEFT D = direct zone H = mixing fixed-point zone M = mixing modulating zone ZONE 2 Type • CENTER D = direct zone H = mixing fixed-point zone M = mixing modulating zone ZONE 3 Type • RIGHT D = direct zone H = mixing fixed-point zone M = mixing modulating zone 0 = not present ACCESSORY QSCCS = frame and door with lock HYDRAULIC DIAGRAM Non-return...

Under - Boiler Units TECHNICAL FEATURES CARATTERISTICHE TECNICHE PERFORMANCES Nominal diameter DN20 Maximum operating pressure PN6 Maximum temperature 90°C Minimum temperature 5°C Fluid type water (max glycol 30%) Maximum flow * • Direct 2100 l/h • Mixing fixed-point 1400 l/h • Mixing modulating 1900 l/h CARATTERISTICHE TECNICHE COMPONENTS Pump Wilo Para 15/7 Interception valve integrated on the system return line Thermometers 0-80°C Thermostatic mixer range 30°C - 60°C Electrical box IP55 Actuators see accessories Control unit see accessories * with residual prevalence of 20 kPa HYDRAULIC CONNECTIONS...

Under - Boiler Units RESIDUAL PREVALENCE DIRECT UNIT MIXING MODULATING FIXED-POINT MIXING MODULATING ELECTRICAL FEATURES The under-boiler units are equipped with an electric box to manage the zone control and boiler control. Below is an example of an electrical connection for the 3-zone unit. The room thermostats must be clean contacts, i.e. voltage-free. BOILER CONTROL BOILER CONTROL clean contact

Under - Boiler Units ACCESSORIES FOR MIXING MODULATING ZONES TECHNICAL FEATURES Electric control 3-point Connection to the ball valve fast push connection Rotation 90° Operating time 35 s 120 s Position indicator rotating arrow Power supply 230V 50/60 Hz Input power 3,9 VA Microswitch closed position                          (mixing valve oriented toward system return) Microswitch power output 1 A resistive - 250 V Protection degree IP54 Cable length 80 cm SINTESI SMART actuator - TECHNICAL FEATURES Positioning control Connection to the ball valve Rotation Operating time Position indicator Power...

Under - Boiler Units EXTERNAL TEMPERATURE PROBE TECHNICAL FEATURES Case material Thermal well material Operating and environmental conditions Probe Minimum insulation resistance Protection degree code RFSONDAE plastic stainless steel -40°C ÷ 100°C, relative humidity: 0 ÷ 100% NTC 100Ω a 100Vdc IP65 / IP67 according to iec60529 note: one external probe for each modulating mixing zone in the under-boiler unit CONTROL UNIT CONNECTION DIAGRAM EXTERAL TEMPERATURE PROBE CONTROL UNIT ROOM THERMOSTAT MODULATING MIXING ZONE SINTESI ACTUATOR PROBE FLOW TEMPERATURE PUMP MODULATING MIXING ZONE EXAMPLE OF...