
Therma 20 Plus
Therma 22 Plus
ThermaCheck Plus
Operating Instructions

INSTRUMENT OPERATION - Where applicable
(Therma 20 Plus and Therma 22 Plus) connect a probe
via the socket located at the top of the instrument,
screw in the collar of the plug, finger tight, to ensure
a secure connection (do not over tighten). Switch the
instrument on and apply the tip of the probe to the
substance or medium to be measured. The instrument
reading may take a few seconds to stabilize, depending
on the nature of the measurement and sensitivity of
the probe.
HOLD - Press the HOLD button to stop measurements
and freeze the display temporarily, press again to
continue measuring.
AUTO-OFF - The unit will switch off automatically after
10 minutes. To disable auto-off press the HOLD button
while switching on the instrument (this is reset when
the instrument is switched off).
OPEN CIRCUIT/FAULTY PROBE - If the probe has
developed an 'Open Circuit' fault the instrument will
display 'Err'.
SENSORS - The ThermaCheck Plus incorporates a fixed
thermistor probe. The Therma 20 Plus operates with
an interchangeable thermistor probe. The Therma 22
Plus operates with either a interchangeable thermistor
or type T thermocouple probe. These instruments
are designed to be compatible with ThermoWorks
manufactured probes.
BATTERY REPLACEMENT - The instrument will display
a low battery symbol to warn that the batteries will need
changing soon. The instrument continues to measure
accurately but after further usage the instrument will
display 'flat bat' and shutdown. Replace the three AAA
batteries located under the rear case half that is held
in place by six screws. Check the seal for damage
and carefully replace the rear case half and re-fit and
tighten the screws.
MAX/MIN - Press the MAX/MIN button to display the
values. The instrument retains the max/min values
when switched off. To reset, press the MAX/MIN button
for three seconds, 'rst' will be displayed.
BACKLIGHT - Press the HOLD button for two seconds.
Please Note: the backlight will not operate if the low
battery symbol is being displayed. (Backlight timeout
= 20 seconds).

°F/°C - Press and hold ON/OFF button for five seconds
at start-up.
GUARANTEE - This instrument carries a two-year
warranty against defects in either components or
workmanship. During this period, products that prove to be
defective will, at the discretion of ThermoWorks, be either
repaired or replaced without charge. This warranty does
not apply to probes, where a six-month period is offered.
Full details of liability are available within ThermoWorks’
Terms & Conditions of Sale at www.thermoworks.com/
product-warranty.
SPECIFICATION - Full specification details of all
products are available at www.thermoworks.com.
(Therma 20 Plus & ThermaCheck Plus)
SPECIFICATIONS
Temperature Range:
Resolution:
Accuracy:
Sensor:
Battery:
Auto-Off:
Display:
Dimensions:
Weight:
Calibration:
–40 to 302°F (–39.9 to 149.9°C)
0.1°
±0.7°F (±0.4°C) from –21.8 to 265.8°F
(–29.9 to 129.9°C)
Thermistor
3x 1.5V AAA, 10,000 hours
After 10 minutes
0.6 inches (15 mm) LCD
5.6 H x 2.8 W x 1.26 D inches
(141 H x 71 W x 32 D mm)
0.49lb. (220g)
NIST-traceable calibration certificate
SPECIFICATIONS
(Therma 22 Plus)
Range (Type T T/C):
Range (Thermistor):
Resolution:
Instrument Accuracy:
Accuracy (Type T T/C):
Accuracy (Thermistor):
Sensor:
Battery:
Display:
Dimensions:
Weight:
Calibration:
–328 to 752°F (–199.9 to 400°C)
–40 to 302°F (–39.9 to 149.9°C)
0.1° to 572°F (300°C) thereafter 1°
±0.4°F (±0.2°C)
±0.9°F (±0.5°C) –58 to 302°F
(–50 to 150°C)
±0.7°F (±0.4°C) –14 to 158°F
(–10 to 70°C)
Type T thermocouple or thermistor
3x 1.5V AAA, 10,000 hours
0.6 inches (15 mm) LCD
5.6 H x 2.8 W x 1.26 D inches
(141 H x 71 W x 32 D mm)
0.49lb. (220g)
NIST-traceable calibration certificate

INSTRUMENT RECORD CARD
Model Order Code
Therma 20 Plus 232-040
Therma 22 Plus 232-041
ThermaCheck Plus 232-042
CALIBRATION
)
32°F (0°C
212°F (100°C
Thermocouple
Thermistor
Serial no. _____________________________________
Calibrated by __________________ Date ____________
This instrument has been checked or calibrated against
reference instrument(s) calibrated by a UKAS Accredited
Calibration Laboratory.
)
ThermoWorks, Inc.
Utah, U.S.A.
P-13-003-02-web Ref: 547-141 / 21.08.19
Ph: 801-756-7705 Fax: 801-756-8948
www.thermoworks.com