SPST Thermostats | McMaster-Carr

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31 Products

Enclosure Thermostats


Adjustable Thermostat (12.6° F Temperature Difference)	Adjustable Thermostat (7° F Temperature Difference)

Fixed Thermostat

Control a single heating or cooling device in your enclosure to keep electronics at a safe operating temperature. Clip them on to a DIN rail and connect them to your heater, fan, or air conditioner. All these thermostats meet American, Canadian, or European safety standards.

Cooling—Cooling thermostats are normally open, so they’ll switch your fan or air conditioner on when the air in your enclosure reaches the temperature setting.

Heating—Heating thermostats are normally closed—when the air in your enclosure reaches the temperature setting, the thermostat will turn the heater off.

Adjustable Actuation Point—Adjustable thermostats let you set the temperature you need.

Fixed Actuation Point—Fixed thermostats have a fixed temperature setting to prevent tampering or accidental changes.

IP20 Enclosure Rating—They have an IP20 rating—to prevent shocks, fingers won’t fit inside.

UL 94 V-0—They also meet UL 94 V-0, so they self-extinguish within 10 seconds if they catch fire and won’t spread the fire by dripping.

Temperature Setting—These thermostats keep the air in your enclosure within a set range. Temperature setting is the high end of the range for both heating and cooling thermostats.

Temperature Difference—Temperature difference is the difference between the temperature when the thermostat turns your device on and when it turns off. For a heater thermostat with a temperature setting of 50° and an 18° temperature difference, the thermostat will switch your heater on when the temperature goes below 32° and off once the temperature reaches 50°. Thermostats with a lower temperature difference maintain a narrower range of temperatures, but they use more power because they switch on and off more frequently.

	Temp.						Overall
	Setting	Difference	Tolerance	Voltage	Current, amp	For DIN Rail Ht., mm	Ht.	Wd.	Dp.	Enclosure Rating	Flammability Rating	Certification		Each
Cooling







				Adjustable Actuation Point

				14° F to 122° F	12.6° F	-7° F to 7° F	120V AC, 240V AC	16	35	2.4"	1.3"	1.6"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, CSA Certified, UL Recognized Component, VDE Certified	0000000	000000


				32° F to 140° F	12.6° F	-7° F to 7° F	120V AC, 240V AC	16	35	2.4"	1.3"	1.6"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, CSA Certified, UL Recognized Component, VDE Certified	00000000	00000
				32° F to 140° F	7° F	-5.4° F to 5.4° F	120V AC, 240V AC, 24V DC to 75V DC	16	35	2 13/16"	1 5/16"	1 11/16"	IP20	UL 94 V-0	CE Marked	0000000	00000




						Fixed Actuation Point

						95° F, 35° C	18° F, 10° C	-11° F to 11° F/-6° C to 6° C	120V AC, 240V AC, 24V DC to 75V DC	16	35	1 7/8"	1 5/16"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000


						122° F, 50° C	18° F, 10° C	-11° F to 11° F/-6° C to 6° C	120V AC, 240V AC, 24V DC to 75V DC	16	35	1 7/8"	1 5/16"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000
						140° F, 60° C	18° F, 10° C	-12.6° F to 12.6° F/-7° C to 7° C	120V AC, 240V AC, 24V DC to 75V DC	16	35	1 7/8"	1 5/16"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000


						Heating







										Adjustable Actuation Point

										14° F to 122° F	12.6° F	-7° F to 7° F	120V AC, 240V AC	16	35	2.4"	1.3"	1.6"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, CSA Certified, UL Recognized Component, VDE Certified	0000000	00000


										32° F to 140° F	12.6° F	-7° F to 7° F	120V AC, 240V AC	16	35	2.4"	1.3"	1.6"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, CSA Certified, UL Recognized Component, VDE Certified	000000	00000
										32° F to 140° F	7° F	-5.4° F to 5.4° F	120V AC, 240V AC, 24V DC to 75V DC	16	35	2 13/16"	1 5/16"	1 11/16"	IP20	UL 94 V-0	CE Marked	0000000	00000




												Fixed Actuation Point

												50° F, 10° C	18° F, 10° C	-9° F to 9° F/-5° C to 5° C	120V AC, 240V AC, 24V DC to 75V DC	16	35	1 7/8"	1 5/16"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000


												59° F, 15° C	18° F, 10° C	-9° F to 9° F/-5° C to 5° C	120V AC, 240V AC, 24V DC to 75V DC	16	35	1 7/8"	1 5/16"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000
												77° F, 25° C	18° F, 10° C	-9° F to 9° F/-5° C to 5° C	120V AC, 240V AC, 24V DC to 75V DC	16	35	1 7/8"	1 5/16"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000

Line-Voltage Thermostats

For Heaters

Regulate line-voltage HVAC systems.

For Heaters—Thermostats for heaters mount to a surface-mount outlet box.

						Overall
	Voltage, V AC	Current, amp	Temp. Setting, ° F	Switch Designation	Electrical Connection Type	Ht.	Wd.	Dp.	For Use Outdoors	Mounting Fasteners Included	Display Type	Certification		Each
For Heaters







				Dial Control

				120 to 277	22	50 to 90	SPST	Hardwire	4 1/2"	2 3/4"	1 1/2"	No	No	Analog	ETL Listed	00000000	000000

Plug-In Line-Voltage Thermostats

Plug in the thermostat, then plug your line-voltage heater into the socket on the thermostat's plug. Use the included metal hanger for mounting.

							Electrical		Overall
	Voltage, V AC	Current, amp	Temp. Setting, ° F	Switch Designation	Cord Lg., ft.	Electrical Connection Type	Connection	No. of Blades	Ht.	Wd.	Dp.	For Use Outdoors	Mounting Fasteners Included	Display Type	Certification		Each
For Heaters







				Dial Control

				120	13	40 to 90	SPST	6	Plug In	Straight Blade	3	5 1/2"	2 1/8"	2 5/8"	No	No	Analog	UL Listed	000000	0000000

Snap-Acting Thermostats

Also known as snap discs, these thermostats switch on cooling systems or switch off heating systems when equipment gets too hot. Each thermostat has five temperature options for switch activation; choose the one that best suits your application.

Unlike heat-actuated switches, these thermostats reset automatically, saving you the effort of replacing a melted fusible link. To calculate their reset temperature, subtract their differential temperature from the temperature you set them at. For example, a thermostat set at 100° F with a 20° F differential will reset at 80° F.

Close Switch at Temperature Setting—Normally closed thermostats are also known as high-limit thermostats—they turn off at a set temperature. They’re often used with electric water heaters, stoves, and furnaces.

Open Switch at Temperature Setting—Normally open thermostats are also known as low-limit thermostats—they turn on at a set temperature. They’re good for use with fans and blowers.

										Overall
	Temp. Setting, ° F	Max. Temp. Differential, ° F	Switch Designation	Switch Starting Position	Voltage, V AC	Current, amp	Wire Connection	Terminal Size	Face Dia.	Ht.	Wd.	Dp.	Hole Diameter (No. of)	Mounting Fasteners Included		Each
Close Switch at Temperature Setting



		90, 100, 110, 120, 130	20	SPST	1 Off	120, 240	25	Quick-Disconnect Terminal	1/4"	3/4"	1 3/4"	2"	1 3/8"	3/16" (2)	No	0000000	000000


		140, 150, 160, 170, 180	20	SPST	1 Off	120, 240	25	Quick-Disconnect Terminal	1/4"	3/4"	1 3/4"	2"	1 3/8"	3/16" (2)	No	0000000	00000


		Open Switch at Temperature Setting



				135, 145, 155, 165, 175	20	SPST	1 On	120, 240	25	Quick-Disconnect Terminal	1/4"	3/4"	1 3/4"	2"	1 3/8"	3/16" (2)	No	0000000	00000


				135, 145, 155, 165, 175	40	SPST	1 On	120, 240	25	Quick-Disconnect Terminal	1/4"	3/4"	1 3/4"	2"	1 3/8"	3/16" (2)	No	0000000	00000
				175, 185, 195, 205, 215	40	SPST	1 On	120, 240	25	Quick-Disconnect Terminal	1/4"	3/4"	1 3/4"	2"	1 3/8"	3/16" (2)	No	0000000	00000
				210, 220, 230, 240, 250	40	SPST	1 On	120, 240	25	Quick-Disconnect Terminal	1/4"	3/4"	1 3/4"	2"	1 3/8"	3/16" (2)	No	0000000	00000
				250, 260, 270, 280, 290	40	SPST	1 On	120, 240	25	Quick-Disconnect Terminal	1/4"	3/4"	1 3/4"	2"	1 3/8"	3/16" (2)	No	0000000	00000

Programmable Line-Voltage Thermostats

Set these thermostats to adjust the temperature at certain times each day. They regulate heaters that use direct electrical power, such as baseboard and wall heaters.

	For System								Overall
	Type	Efficiency	Program Function	Voltage, V AC	Current, amp	Temp. Setting, ° F	Switch Designation	Electrical Connection Type	Ht.	Wd.	Dp.	For Use Outdoors	Mounting Fasteners Included	Display Type		Each
For Heaters







				Push-Button Control

				Electric	Single Stage	Daily	120	16	40 to 86	SPST	Hardwire	4 7/8"	2 3/4"	7/8"	No	Yes	Digital	0000000	0000000


				Electric	Single Stage	Daily	240	16	40 to 86	SPST	Hardwire	4 7/8"	2 3/4"	7/8"	No	Yes	Digital	0000000	000000

Enclosure Thermostats for Multiple Devices

Keep electronics in your enclosure from getting too hot or cold with these thermostats that control two devices at once. Clip them to a DIN rail to install.

For Heating and Cooling Thermostats with Two Actuation Points


Adjustable Thermostat with Two Actuation Points	Fixed Thermostat

Cooling thermostats regulate two cooling devices, such as a fan and an air conditioner, for two-stage cooling. Use only one device for cooling in mild temperatures or both for extreme heat. These thermostats switch your equipment on when the enclosure is hotter than the temperature setting. Once the temperature is reduced by the temperature difference, it will switch off. For example, a thermostat set at 77° F for a fan and 140° F for an air conditioner will power both devices when the enclosure is over 140° F. With a temperature difference of 18° F, the air conditioner will switch off when the temperature goes below 122° F. The fan will run until the temperature reaches 59° F, and switch back on if it heats up to 77° F or hotter.

Heating and cooling thermostats control heaters and fans or air conditioners.

Heating and cooling thermostats with two actuation points control two devices independently. When your enclosure temperature is within the set range, neither device is powered, so they’re more efficient than changeover thermostats. For each device, temperature setting is the high end of the temperature range, and temperature difference is the size of the range. For a thermostat with temperature settings of 59° and 95° F and an 18° F temperature difference, the heater will switch on when your enclosure is colder than 41° F and turn off when it reaches 59° F. The fan or other cooling device will switch on when the temperature goes above 95° F and turn off once the enclosure cools to 77° F.

Adjustable Actuation Point—Adjustable thermostats allow you to set custom temperatures.

Fixed Actuation Point—Fixed thermostats prevent tampering and accidental changes.

IP20 Enclosure Rating—All thermostats meet IP20, which means they’re designed so fingers can’t fit inside and get shocked.

UL 94 V-0—They also meet UL 94 V-0, so they self-extinguish within 10 seconds if they catch fire and won’t spread the fire by dripping.

Certification—Thermostats that are CE marked or VDE certified meet European safety standards. UL Recognized Component and C-UL Recognized Component thermostats also meet American and Canadian safety standards.

	Heating Temperature			Cooling Temperature				Overall
	Setting	Difference	Tolerance	Setting	Difference	Tolerance	Voltage	Ht.	Wd.	Dp.	Enclosure Rating	Flammability Rating	Certification		Each
Adjustable Actuation Point



		14° F to 122° F	12.6° F	-7° F to 7° F	68° F to 176° F	12.6° F	-7° F to 7° F	120V AC, 240V AC	2 5/8"	2"	1 13/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, CSA Certified, UL Recognized Component, VDE Certified	0000000	000000


		32° F to 140° F	12.6° F	-7° F to 7° F	32° F to 140° F	12.6° F	-7° F to 7° F	120V AC, 240V AC	2 5/8"	2"	1 13/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, CSA Certified, UL Recognized Component, VDE Certified	0000000	00000


		Fixed Actuation Point



				59° F, 15° C	18° F, 10° C	-9° F to 9° F, -5° C to 5° C	95° F, 35° C	18° F, 10° C	-12.6° F to 12.6° F, -7° C to 7° C	120V AC, 240V AC, 24V DC to 75V DC	1 7/8"	2 1/2"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000


				59° F, 15° C	18° F, 10° C	-9° F to 9° F, -5° C to 5° C	122° F, 50° C	18° F, 10° C	-12.6° F to 12.6° F, -7° C to 7° C	120V AC, 240V AC, 24V DC to 75V DC	1 7/8"	2 1/2"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000
				77° F, 25° C	18° F, 10° C	-9° F to 9° F, -5° C to 5° C	122° F, 50° C	18° F, 10° C	-12.6° F to 12.6° F, -7° C to 7° C	120V AC, 240V AC, 24V DC to 75V DC	1 7/8"	2 1/2"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000

For Cooling Thermostats with Two Actuation Points

Adjustable Thermostat

with Two Actuation Points

Fixed Thermostat

Adjustable Actuation Point—Adjustable thermostats allow you to set custom temperatures.

Fixed Actuation Point—Fixed thermostats prevent tampering and accidental changes.

IP20 Enclosure Rating—All thermostats meet IP20, which means they’re designed so fingers can’t fit inside and get shocked.

UL 94 V-0—They also meet UL 94 V-0, so they self-extinguish within 10 seconds if they catch fire and won’t spread the fire by dripping.

	Cooling Temperature			Cooling Temperature Second Actuation Point				Overall
	Setting	Difference	Tolerance	Setting	Difference	Tolerance	Voltage	Ht.	Wd.	Dp.	Enclosure Rating	Flammability Rating	Certification		Each
Adjustable Actuation Point



		32° F to 140° F	12.6° F	-7° F to 7° F	32° F to 140° F	12.6° F	-7° F to 7° F	120V AC, 240V AC	2 5/8"	2"	1 13/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, CSA Certified, UL Recognized Component, VDE Certified	0000000	000000


		Fixed Actuation Point



				122° F, 50° C	18° F, 10° C	-12.6° F to 12.6° F, -7° C to 7° C	140° F, 60° C	18° F, 10° C	-12.6° F to 12.6° F, -7° C to 7° C	120V AC, 240V AC, 24V DC to 75V DC	1 7/8"	2 1/2"	1 5/16"	IP20	UL 94 V-0	C-UL Recognized Component, CE Marked, UL Recognized Component, VDE Certified	0000000	00000

Tamper-Resistant Line-Voltage Thermostats


	Thermostat with Tamper-Resistant Guard Removed

A built-in guard prevents accidental changes and other tampering and protects these thermostats from damage. These thermostats regulate the temperature in HVAC systems that use direct electrical power. They’re often used with baseboard and wall heaters.

						Overall
	Voltage, V AC	Current, amp	Temp. Setting, ° F	Switch Designation	Electrical Connection Type	Ht.	Wd.	Dp.	For Use Outdoors	Mounting Fasteners Included	Features	Display Type	Certification		Each
For Heaters







				Dial Control

				120 to 277	22	50 to 90	SPST	Hardwire	4 9/16"	2 13/16"	1 3/4"	No	No	Tamper-Resistant Guard	Analog	ETL Listed	0000000	000000