The Criterion temperature chamber series provides an economical and space-saving solution for a variety of temperature testing requirements. The chamber's interior size is 3.5 inches wider than traditional benchtops, yet the exterior is 20% narrower. The BTU-133, BTU-433, and BTZ-133 chambers use 115V power, meaning no special power hook-ups.

  • Lowest temperature: -20 or -70°C (-4 or -94°F)
  • Highest temperature: 180°C (354°F)
  • Chamber sizes: 1.5 or 4 cubic feet
  • Touch-screen Watlow F4T programmer with Ethernet access

The extended temperature ranges of the Criterion series make testing at extreme conditions possible without buying a larger, stand-alone chamber. Two chamber sizes are available, as well.

The programmer includes a temperature alarm as just one part of ESPEC's three-tiered over-temperature protection system. A thermal fuse and a user-set independent limit are also included. In addition, a specimen power terminal allows the user to safely operate powered equipment inside or with the chamber.

Features for Criterion Temperature Benchtop Chambers
  • High performance and quiet operation (65 dBa)
  • Space-saving footprint, designed for flush installation to wall
  • Stainless steel exterior
  • Full thermal break around doorframe
  • One 50mm (2") diameter cable port on left, with flexible silicone plug
  • Three levels of overheat protection, plus overcool protection
  • Easy lift-off service panels, electrical access on left
  • Detachable eight-foot power cord with plug
  • ETL listed electrical panel conforming to UL 508A

Touch-screen programmer/controller with Ethernet

  • Watlow F4T with touch-screen and Ethernet port standard
  • Save 40 profiles with up to 50 steps each (ramp, soak, jump, auto-start, end)
  • One event relay for external device control, plus specimen power interlock relay for safety
  • ESPEC exclusive options include: Web Controller for full remote access; Chamber Connect software for basic data logging and monitoring. USB and RS-485 ports available, as well.

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Photo of Criterion Temperature Benchtop
Compact and easy to use

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The F4T is the newest programmer/controller from Watlow, with a touch-screen and Ethernet interface. ESPEC offers optional software for remote management and datalogging. 

Touch-screen programmer/controller with Ethernet

  • One event relay for external device control, plus specimen power interlock relay for safety
  • ESPEC exclusive options include: Web Controller for full remote access; Chamber Connect software for basic data logging and monitoring
  • USB memory and RS-232/485 ports available as options
  • Save 40 profiles with up to 50 steps each

F4T Specification: (ESPEC Configuration)


Color touch-screen, 4.3 inches
Quickly and easily identify process, alarm, and setpoint values

Control Method

PID (Proportional, Integral, Derivative)


Standard: Ethernet with MODBUS & SCPI
Optional: RS-232/485, Web Controller
Only one interface type may be installed

Operating Modes

STOP: chamber off, programmer on
PROGRAM: Runs selected test profile
CONSTANT: runs at set value continually

Program Capacity

40 profiles, 50 steps per program

Programming Capabilities

Ramp and soak functions
Profiles can be programmed to wait for events or up to three process variables
Soak control delays timer until setpoint is reached

Additional Functions

High/low limit alarm functions
Digital inputs can be programmed remotely, start, pause, terminate profiles
A real-time clock can be used to start a profile at any time
Controller is UL/CUL & CE listed

Constant Mode

Used for quickly setting a single operating condition. Chamber will continue to run this condition until stopped. Program and other settings may be entered while the system is running.

Software Options

Learn more about ways to access ESPEC controllers via software our support page:
Software for Watlow F4T

Recommended: Web Controller

The ESPEC Web Controller is an embedded server/software solution for monitoring and programming your chamber via Ethernet. Works with P-300, SCP-220, F4T, & F4 controllers.

See the brochure
Self-install kit for existing units
Try the live demo now!

Independent of the controller itself, the Web Controller adds additional capabilities for datalogging, programming, alarm emails, and RESTful API.

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