Thermostats regulate temperature in non-critical applications. They sense temperature, within a preset range and cycle heaters on and off to maintain the set point.
Thermostats may be mounted inside a terminal enclosure or remote mounted (separate from the heater assembly). If using a remote mounted thermostat, be sure to order the sufficient capillary tube length to permit installation.
All Watlow thermostats are normally closed circuit and either single-pole, single-throw (SPST) or double pole, single-throw (DPST). They can be used with or without an enclosure.
Thermostat selection should be based on temperature range, capillary tube length and sensor bulb size (diameter/length).
Thermostat Conversion Kits
|S-PCK, Single-Pole Conversion Kit|
D-PCK, Double-Pole Conversion Kit
|DPST, 1-phase, DPST, 1-phase Interconnected Wiring|
DPST, 3-phase delta, DPST, 3-phase delta Interconnected Wiring
SPST, 1-phase, SPST, 1-phase Interconnected Wiring
SPST, 1-phase, SPST, 1-phase Pilot Duty Wiring
SPST, 3-phase delta, SPST, 3-phase delta Pilot Duty Wiring
SPST, 3-phase wye, SPST, 3-phase wye Pilot Duty Wiring
Thermostats with Enclosures
|NEMA 1-SDP, General Purpose Single- and Double-Pole|
NEMA 4-SP, Moisture Resistant Single-Pole
NEMA 4-DP, Moisture Resistant Double-Pole
NEMA 7-SP, Explosion Resistant Single-Pole
NEMA 7-DP, Explosion Resistant Double-Pole
|1, Thermostat for Bulb and Capillary|
11, Thermostat for Bulb and Capillary
12A, Thermostat for Bulb and Capillary
2, Thermostat for Bulb and Capillary
2A, Thermostat for Bulb and Capillary
3, Thermostat for Bulb and Capillary
3A, Thermostat for Bulb and Capillary
4, Thermostat for Bulb and Capillary
5A, Thermostat for Bulb and Capillary
7A, Thermostat for Bulb and Capillary
8, Thermostat for Bulb and Capillary
9, Thermostat for Bulb and Capillary
|D, Dust Resistant (NEMA 12)|
E, Explosion Resistant (NEMA 7)
E/W, Explosion/Moisture Resistant (NEMA 7/4)
S, General Purpose (NEMA 1)
W, Moisture Resistant (NEMA 4)
|CB, Chrome Bezel|
CD, Celsius Dial Scale
LTB, Liquid-Tight Brass Fitting (3/8 in. - 18 NPT)
PL11, Pilot Light, 120V only available on NEMA 4/7 and 7
|An optional pilot light gives visual indication whether the power supplied to the heating element(s) is on or off.|
|Thermostats are shipped with Fahrenheit (ºF) dial scales. If your application requires a Celsius (ºC) scale, order the optional dial face. To order, specify code CD. Scale will match thermostat temperature range.|
|Do not use thermostats for high-limit sheath protection. Thermostats fail in a closed circuit mode and will not cut power to the heaters. Limit control should be provided by an isolated, redundant sensor and control system of the appropriate type, design and installation.|
Thermostats are precalibrated at the factory. No adjustment, other than selecting the desired operating temperature, is required. All wiring should be performed by qualified personnel and comply with the National Electrical Code and other applicable state and local codes.
To help assure the correct thermostat is selected as well as installed and wired properly, here are a few helpful hints. Schematics are provided for interconnecting thermostats to single- and three-phase heaters.