stemco
Two Stage Bulb & Capillary Thermostats
The 352 Series Bulb & Capillary Thermostats utilize two separate switches for two-stage or double-pole switch action. These switches can be configured in any combination of SPDT Automatic Reset Switches and/or 2 SPST Manual Reset Switches, providing flexible control options for various applications.
This thermostat can be used for a combination of heating & cooling, or fan & limit control, all from one thermostat. It’s also ideal for three-phase or double line break applications, offering versatile temperature regulation in demanding environments.
QUALITY AMBIENT COMPENSATION
Our capillary thermostats feature ambient compensation to offset temperature differentials, ensuring greater accuracy as environmental conditions change. This technology helps maintain reliable temperature control, even in fluctuating surroundings, making our thermostat controls ideal for dynamic applications.
CERTIFIED
Senasys ensures the quality control & reliable operation of all our products. Every capillary thermostat is 100% tested individually before leaving our facility to guarantee consistent performance. Our capillary thermostats are UL & cUL approved, meeting industry standards for safety & reliability.
CUSTOM OPTIONS
Senasys capillary thermostat switches are available as custom-built temperature control solutions, tailored to meet your exact specifications. This ensures you receive the precise capillary thermostat switch you need, without paying for unnecessary features, optimizing both performance & cost.
MADE IN U.S.A.
All Senasys products are designed, manufactured, tested, & shipped from our facilities in Eau Claire, WI to clients worldwide. Every switch is individually 100% tested for quality & performance before leaving our plant, ensuring reliable operation for every customer.
The Type 352 Series Bulb & Capillary Thermostats utilize two separate switches for two-stage or double-pole switch action. These switches can be configured in any combination of SPDT Automatic Reset Switches and/or 2 SPST Manual Reset Switches, offering versatile control for various temperature regulation needs.
The differential between the switches can be factory-set very close for double-pole applications or wider for multistage applications. Wiring the two double throw switches in series allows the 352 series thermostat to be used where a large differential between on & off is required. The switches can also be wired together to create a heating/cooling thermostat with a dead band, providing precise control in complex systems.
The combination of an automatic reset & a manual reset switch is perfect for applications where the automatic reset switch controls the system, and the manual reset switch serves as a safety or limit switch, ensuring reliable protection.
Key Specifications:
- Temperature Range: 0°F – 700°F
- Temperature Options: Adjustable or Fixed Temperature
- Reset Options: Automatic or Manual Reset
- Switch Action: 2 SPDT Switches
- Amperage: 15 – 25 Amps per Switch
- Mounting Options: Panel, Back, or House Mounting
- Terminal Location: Front Terminals
- Maximum Ambient Temperature: 250°F
- Adjustment Options: Screw Driver or D Shaft Adjustment
- Material Options: Copper, Nickel Plated Copper, or Stainless Steel Bulb & Capillary Options
Cross Reference
We are confident in the quality of our 352 Series Two-Stage Capillary Thermostats, which is why we’ve compared our model to top competitors in the market, such as Selco & Robertshaw®. Our 352 Series offers a temperature range of 0°F to 700°F, 250°F max ambient, and options for adjustable & fixed temperatures, along with auto reset capabilities.
Explore the comparison table to see how STEMCO stands out in terms of performance and features.
Let me know if this version works for you!
BRANDS
STEMCO
352 Series
SELCO
ROBERTSHAW
0°F to 700°F Temperature Range
250°F Max Ambient
Adjustable Temperature
Fixed Temperature
Auto Reset
Manual Reset
Two Stage
Screw Terminals
Rated up to 25 Amps @ 250VAC
Copper or Stainless Steel Material
Multiple Mounting Options
UL / cUL Recognized
Made in U.S.A.
Common Applications
Two-Stage Bulb & Capillary Thermostats are commonly used in HVAC equipment to control & limit the heating element temperature, ensuring efficient and reliable operation.
HVAC
Dimensional Drawings
Our two-stage bulb & capillary thermostats come with either a screwdriver or D-Shaft adjustment knob, & are available in panel, back, or housed mounting options for easy integration into your equipment. All dimensions are provided in inches/millimeters for precise installation.

Screw Driver adjustable, shown with back mount, & two SPDT automatic reset switches.

Adjustable with D-Shaft shown with housing, & two SPDT automatic reset switches.

Screw driver adjustable shown with front panel mount, & two SPST manual reset switches.

Screw driver adjustable shown with back mount, & two SPDT automatic reset switches.
Mounting ear options illustrated.
Fitting Options
Our Two-Stage Bulb & Capillary Thermostats are available with a range of standard fittings & bulb supports, offering flexibility for various applications.
See the available fitting options below.
Standard Fittings

Thread
Material
Hex Size
‘L’ Length
Finish
Part #
1/8 NPT
Brass
7/16″
0.625″
None
368-67-03061
1/8 NPT
S-Steel
7/16″
0.625″
None
368-67-03023
1/4 NPT
Brass
5/8″
0.750″
None
368-67-03201
1/4 NPT
Brass
5/8″
0.750″
Nicked Plated
368-67-03202
1/4 NPT
S-Steel
5/8″
0.750″
None
368-67-03161
3/8 NPT
Brass
11/16″
0.750″
None
368-67-03001
3/8 NPT
Brass
11/16″
0.750″
Bright Nickel
368-67-03001P
3/8 NPT
S-Steel
11/16″
0.750″
None
368-67-03002
1/2 NPT
Brass
7/8″
0.875″
None
368-67-03101
1/2 NPT
Brass
7/8″
0.875″
Bright Nickel
368-67-03102
1/2 NPT
S-Steel
7/8″
0.875″
None
368-67-03103
Bulb Support Fittings
Our Two-Stage Bulb & Capillary Thermostats come with a variety of standard fittings & bulb supports, providing flexibility for different applications.
See the available bulb support fittings below.
Standard Bulb Support Fittings

Thread
Material
Hex Size
‘L’ Length
‘A’ Dia.
‘B’ Dia.
Finish
Part #
1/4 NPT
Brass
5/8″
1.620″
0.257″
0.390″
None
368-67-03241
1/4 NPT
S-Steel
5/8″
1.620″
0.147″
0.390″
None
368-67-03242
1/4 NPT
S-Steel
5/8″
1.620″
0.257″
0.390″
None
368-67-03243
1/2 NPT
S-Steel
7/8″
1.372″
0.257″
0.315″
None
368-67-03261
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