The Heat Meter Packs are available to meter the energy usage in centralised Heating and Cooling installations. These pump units accommodate the easy mounting of the Heat Meter. The second temperature sensor is directly put into the isolating valve of the supply pipework, without any adapter or pocket. The special 3-way ball valve, placed after the circulating pump, allows the lead sealing of the sensor and the replacement of it without draining the installation: it is sufficient to close the valve and isolate the sensor from the hydraulic circuit. In this way the placement of the energy meter, after having cleaned and serviced the circuit or replaced it, is very easy.