ASAHI US-628 Waterproof Thermostats

The Asahi US-628 waterproof disc thermostat offers IP67 integrity in a very neat, epoxy-sealed housing.  By sealing the integral lead-wires and mounting flange with a combination of epoxy and o-rings, the US-628 can be used in applications where moisture ingress has previously been a problem.  Also as this control is totally sealed, the US-628 could be considered for use in some ATEX applications.

The US-628 uses the same high-quality snap-action bimetal discs as the US-622 series and so it can be used as a tight differential control device.  Available with open-on-rise or close-on-rise contacts, the US-628 can switch loads upto 5A/250VAC with factory preset calibrations upto 130˚C.

The sealed design also makes it suitable for use in gas or oil heating appliances and carries Japan’s JIA approval.  Using one of the various air-flange mounting options, the US-628 can be used to monitor air temperature in such appliances.  High quality, very low resistance electrical contacts means that it can be readily incorporated in the thermocouple circuit.

Standard lead-wires are 100mm long 20AWG PVC (115˚C) or FEP (rated to 180˚C), other lengths available for volume applications.


  • Refrigeration controls
  • Gas and oil appliances (JIA approval)
  • Fuel-cells
  • Anti-condensation controls
  • Anti-frost heaters


  • IP67 rated drip-proof housings
  • Integral lead-wires
  • Calibration range +30˚C to +130˚C
  • 5A/250VAC contact rating
  • C-UL & CMJ approval
High quality snap action bimetal disc thermostat. tight differential control. IP67 rating | ATC Semitec for advice and samples