The Everwell W1609‑101 is a remote‑bulb mechanical refrigeration thermostat / temperature controller used in refrigeration systems (cold rooms, milk tanks, beverage dispensers, ice machines, etc.).
everwellparts.com
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It uses a capillary sensor (bulb + capillary tube) to sense the temperature at the point where the bulb is mounted or immersed, and then actuates a switch in the controller housing.
AusPower Australia
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everwellparts.com
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The control action is “close on rise”, meaning as the sensed temperature rises past the setpoint + differential, the contact inside closes (energizing whatever load is connected).
everwellparts.com
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It comes with a 5 ft capillary length (i.e. the bulb and tube assembly is ~5 ft long) from the main housing to the sensing bulb.
everwellparts.com
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AusPower Australia
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It is UL‑listed (UL file E486748) indicating it meets certain safety and performance standards.
everwellparts.com