stemco
351 Stemco Capillary Thermostats
The 351 Stemco Capillary Thermostats are our most versatile line of remote sensing thermostats available in Bulb and Capillary Tube or Probe styles. Many variations are available in each style to include fixed or adjustable temperatures, auto or manual resets, Copper/Plated Copper or Stainless steel construction and all variations have multiple mounting options.
quality ambient compensation
Our capillary thermostats also offer the option of being ambient compensated to offset the differential in temperature which keeps our thermostat controls more accurate as it’s environment changes.
CERTIFIED
Senasys takes pride in quality control and reliable operation of our products. Every switch is individually 100% tested before it leaves the plant. Our capillary thermostats are UL & cUL approved.
CUSTOM OPTIONS
Capillary thermostat switches built by Senasys can also be built to customer specifications. This insures you get the exact control you want without paying for features you don’t need.
MADE IN U.S.A.
Products are designed, manufactured, tested and shipped from Senasys’ facilities in Eau Claire, WI to clients across the globe. Every switch is individually 100% tested before it leaves the plant.
The 351 Stemco Capillary Thermostats are our most versatile line of remote sensing thermostats available in Bulb and Capillary Tube or Probe styles. Many variations are available in each style to include fixed or adjustable temperatures, auto or manual resets, Copper/Plated Copper or Stainless steel construction and all variations have multiple mounting options.
The fixed temperature models are typically used for safety or high and low limit applications.
All options are available in both the probe style more typical of a boiler type installation or as a Bulb and capillary tube for more remote temperature sensing.
The 351 series offers numerous mounting options that allow for simple replacement of competitor’s thermostats.
The temperature range determines when the thermal switch will close, or engage the electrical circuit, and when it will automatically reset, or open. These switches can also be manually reset for when you need to call special attention to a temperature malfunction.
- 0°F to 700°F Temperature Range
- Fixed, or Adjustable Temperature Range
- Automatic, or Manual Reset
- SPDT Switch Action
- 15-30 Amps @ 120VAC
- 250°F Maximum Ambient Temperature
- Panel, Back or Side Mounting Options
- Housing Optional. See catalog for more information.
- Front Terminal Locations
- Screw Driver or D-Shaft Adjustment
- Copper, Nickel Plated Copper, One Piece Stainless Steel, or Two Piece Stainless Steel Available
Boiler Controls

Boiler Control with Adjustable Temperature Setting & Auto Reset. Shown with Thermowell & Housing.

Boiler Control with Adjustable Temperature Setting & Auto Reset. Shown with Thermowell.

Probe Style with Fixed Temperature & Manual Reset. Shown with 3/4″ NPT Fitting & Housing.

Probe Style with Adjustable Temperature Setting & Auto Reset. Shown with 3/4″ fitting.

Probe Style with Fixed Temperature & Auto Reset. Shown with 7/16″-24 Loxit Fitting (not standard).
Cross Reference
We are certain of our position at the top so we’re comparing our 351 Bulb and Capillary Thermostats with other top brands.
BRANDS
STEMCO
351 Series
SELCO
CAP & FS Series
PECO
T125, T103, L107, or L117 Series
ROBERTSHAW
B10, C1, LC, OR K&S Series
E.G.O.
EF55 OR EF51 Series
0°F to 700°F Temperature Range
Adjustable Temperature
Screw or D-Shaft Adjustment Knob
Fixed Temperature
250°F Max. Ambient
Auto or Manual Reset
Single Stage
Screw Terminals
Rated up to 25 Amps @ 250VAC
Copper or Stainless Steel Material
UL / cUL Recognized
Made in U.S.A.
Mounting Options
Our single stage bulb & capillary thermostats are available with a screw driver or D-Shaft adjustment knob, & can be panel, side or housed for mounting into your equipment. All dimensions shown below are inches/millimeters.
The Screwdriver adjustment model with its front connect terminals is perfect for warming ovens, deep fat fryers, and commercial water heaters. The D-Shaft adjustable model allows for easy installation of a knob, making it ideal for application s such as convection ovens, charbroilers, dishwashers, grills, electric toasters and toaster ovens. The Fixed setting model is used when no user adjustment is desired, such as for safety limits.
Every 351 thermostat is built to customer specifications. This insures that you get the exact control you want without paying for features you don’t need.
Most Brackets are Interchangeable.

Front Mounting Bracket, for Screw Driver Adjustable Model, with Auto Reset, 4 Hole Large Opening


Front Mounting Bracket, for D-shaft Adjustable Model with Auto Reset


Front Mounting Bracket, for or Fixed Setting Model with Manual Reset


Flat Side Mounting Bracket, shown with Fixed Setting Model with Manual Reset


Raised Side Mounting Bracket, shown with Fixed Setting Model with Manual Reset


Flat Base Mounting Bracket, shown with Fixed Setting Model with Auto Reset.

Fitting Options
Our Single Stage Bulb & Capillary Thermostats are available with a variety of standard fittings & bulb supports.
See 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 Single Stage Bulb & Capillary Thermostats are available with a variety of standard fittings & bulb supports.
See 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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