Harwil 46 mm flow switch

This flow sensor ensures that the circulation pump delivers a sufficient flow of water to the heater to prevent overheating. If the flow is sufficient, the magnet sticks against the sensor rod and the flow information is sent to the control system.

This Harwil detector has a 1/2" MPT thread that screws into a tee or heater union with 1.5-inch or 2-inch pipe fittings. The stem length is suitable for 1.5-inch or 2-inch pipe sizes (48 to 63 mm diameter). It is designed for a maximum current of 0.5A.

Dimensions (size "Large", in red on the diagram)
Thread diameter: 21 mm (1/2 inch MPT type)
Length of contact pin: 46 mm

Part numbers
Harwil: Q12DSMSC
Hydroquip: 34-0217, 34-0110F
Allied: 5-20-0025, 5-20-0009
Old part numbers: Q12DS501.54SNO1, 60-1008

Installation instructions