The VPNs are two 'through' solenoid valves: they are manifold-mounted without the use of fittings, tools and Teflon and are screwed together manually in series by means of the 1" female swivel ring with o-ring seal and the 1" male thread. At the outlet of the solenoid valve with the 1" female swivel nut, a compression fitting must be inserted to connect the sector pipe. This process speeds up installation by guaranteeing a compact manifold, thanks to which a total of 12 solenoid valves can be concentrated in the thermowell for easy and convenient maintenance.