Differential pressure switch detect quickly flow in the heat exchanger. They are extremely reliable since they are not affected by dirt and have no flow restriction.
It can be installed on any pipe size. One size fits all.
Instantaneous Domestic Hot WaterStart the heat exchanger pump when there is a DHW flow.
Specification Flow Switch: 0.5gal/min (1l/min)Contact Rating: 500W Material: Brass Cable: 20/2 - 10ft (3m)Connection: 1/4" NPT