Insulated Load Unit with an actuated 3-way mixing valve (Kvs = 6.3 m3/h), 2 pumps, TSV3B 55°C load valve, ball valves, drain valves, a safety valve, thermometers. The Unit is intended for heating systems with a solid fuel boiler & thermal store, permitting DHW heating. Heating system water is mixed in a 3-way mixing valve with el. actuator, the temperature of return water to a boiler is kept at 55°C min. by a load valve. Boiler heat surplus is stored into a thermal store. Heating output is controlled by an external Controller through the actuated mixing valve.