Resideo L4008B1013 Control 318172 701 protecting sensitive downstream components and protecting sensitive downstream components and ensuring quieter mechanical room operations The ASCO 8210G7 24V is a high performance 2 way normally closed solenoid valve designed for reliable fluid control in demanding HVACR and industrial applications This specific model is wired for circulator application because the contacts make on temperature rise this unit features a Single Pole Single Throw (SPST) micro switch that uses contacts make on temperature rise logic to initiate circulator cycles once the boiler reaches the necessary operating threshold