The Fenwal Thermoswitch Temperature Controller is a 5/8″ diameter cartridge-style mechanical thermostat with an adjustable temperature set point. The Series 18000 has a coupling fitting with standard 1/2″ NPT (3/4″ NPT on 18052) male pipe threads at each end either of which may be used for mounting. Corrosion Resistant (Series 18000) – Certain models are designed to be corrosion resistant. Type 316 Stainless Steel is used throughout for corrosion resistance.

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All Variations

Part No.DescriptionPriceQuantityAdd to Cart
01-018002-000Fenwal Thermoswitch$340.00
01-018023-000Fenwal Thermoswitch$340.00
01-018052-000Fenwal Thermoswitch$452.00
01-180020-029Fenwal Thermoswitch$443.00
01-018002-021Fenwal Thermoswitch$413.00
01-018023-007Fenwal Thermoswitch$413.00

The Fenwal Series 18000 Coupling Head Thermoswitch can be inserted into a .625 in. reamed hole, except for the 18052 which can be inserted into a .750 reamed hole. Lightweight and compact, these units are economical temperature controllers or stand-alone high or low limit controllers. The Thermoswitch controllers control temperatures as low as -100ºF and as high as 600ºF with the proven dependability of over 60 years of service to satisfied customers.
Principle of Operation:
The Fenwal Thermoswitch controller is a strut-and-tube type thermostat comprised of two basic parts: the outer shell, made of high-expanding metal and the strut assembly made of low-expanding metal. A pair of electrical contacts is mounted on the strut assembly and installed in the shell under tension. The temperature at which the contacts “make” or “break” can be regulated by a temperature adjusting sleeve.
Fast Response:
Because the outer shell of the Thermoswitch controller is the active sensing member, and not merely a housing, response to temperature change is almost instantaneous.
Close Control:
The controller’s shell and strut arrangement has “anticipation” characteristics which substantially reduce the amount of overshoot and undershoot during conditions of rapid temperature change.
Extreme Sensitivity:
The strut and contact assembly operates by slow make and break. This means that every temperature change, no matter how small, causes a corresponding change in the space between the electrical contacts. Therefore, contact action can be produced by a very small temperature change, which accounts for the Thermoswitch controller’s excellent resolution os 0.1ºF (0.05ºC).

Agency Approval:
Various models are listed to component recognized by Underwriters Laboratories (UL) and certified by the Canadian Standards Association (CSA).

Specifications & Options:

  • Shell dimensions: 5/8″ diameter, 3-9/16″ long (3″ long on units with threads)
  • Standard lead wire: 8-10 inches
  • Maximum volts: 240VAC / Vdc consult factory
  • Maximum watts: 1200 AC / Vdc consult factory
  • Maximum operating temperature: 600ºF / 316ºC
  • Minimum operating temperature: -100ºF / -73ºC
  • Contact action: slow make and break
  • Options (call for pricing and applicability to specific models):
      • Special Marking
      • Extended Lead Wires
      • Factory Temperature Setting
      • Temperature Restraining Device
      • Tamper-Proof Cap
      • Dial and Knob
      • Moisture Resistant Seal & Moisture Resistant Tamper Proof Cap
      • Armored Cable (over lead wires)
      • Terminal Plug Connector
      • Extended Temperature Adjusting Sleeve
      • Protective Wells
    Fenwal Series 18000 Coupling Head Thermoswitch – Technical Data & Specifications
    Model No.


    Temperature Range

    Shell Material Corrosion Resistant
    Contact Operation
    on Temp. Rise

    01-018000-000 5/8″ -100 to 400ºF Brass No Opens Discontinued, use
    01-018002-000 below
    01-018021-000 5/8″ -100 to 400ºF Brass No Closes Discontinued, use 01-018023-000 below
    01-018002-000 5/8″ -100 to 600ºF 300SS No Opens $330.00
    01-018023-000 5/8″ -100 to 600ºF 300SS No Closes $330.00
    01-018052-000 13/16″ -100 to 600ºF 300SS No Opens $439.00
    01-180020-029 5/8″ -100 to 500ºF 316SS Yes Opens $430.00
    01-018002-021 5/8″ -100 to 600ºF 316SS Yes Opens $401.00
    01-018023-007 5/8″ -100 to 600ºF 316SS Yes Closes $401.00
  • 01-018002-000 | 01-018023-000 | 01-018052-000 | 01-180020-029 | 01-018002-021 | 01-018023-007 | 18000-0 | 18002-0 | 18021-0 | 18023-0 | 18052-0
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Fenwal Series 18000 Thermoswitch
$340.00$452.00Select options