Insulated Load Unit with 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 with no thermal store, permitting DHW heating. It ensures automatic mixing of heating water to a temperature corresponding to the boiler output. The temperature of return water to a boiler is kept at 55°C min. by a load valve. Heating output can be controlled directly on the boiler, e.g. by RT4 or RT3-E thermostatic draft regulators with a room thermostat.