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THERMOMETER with LED Display and optional Alarm or Relay

Model series SDM-4
With 1 or 2 external temperature sensors
Models for 120Vac, 208-250Vac, 
12V and 24V AC/DC
Optional Alarm Relay or Buzzer
Optional Min Max Temp memory
Optional Remote Control + Display Panel
Temperature range: -40F (-40C ) to 255F ( 124C )
Higher custom ranges available up to 960F ( 515C )
Heating and/or Cooling and differential modes

Digital Thermometer mounting in 1-gang box

Installation example 
in 1-gang wiring box

SDM-4 Digital Thermometer face plates

Red, Green or Blue
LED display

Black, White or Custom
labels available

Metal Face
Dim's:  4.5" x 2.75" x 0.5"
115mm x 70mm x 12mm


Sauna Control Panel
Infra Red Sauna Control
Spa Controller
Steam Bath Control
Heating Monitor
Cooling Monitor
HVAC Monitor
Refrigeration Monitor
Water Tank Temperature Alarm
Yoga Room Temperature
Freezer Temperature Display
Solar Water Heater Monitor
Ventilation Control
Chiller Monitoring
Pool Temperature Display
Train Car Thermometer
Bus Cabin thermometer
Greenhouse Temperature Monitor
Temperature Monitoring and Alarm
Heat / Cool Process Control
Temperature Difference Monitor


  • Accurate digital temperature display
  • Sensor wire up to 500ft (150M)
  • For Heating, Cooling or Refrigeration
  • High Low Temperature memory
  • Automatic self-calibration
  • Programmable temperature limits
  • Large LED display
  • Preset Alarm values
  • Quiet operation
  • Optional internal Alarm Buzzer
  • Simple wiring
  • Message on display when error detected


  • Remote Display panel
  • Extended temperature ranges
  • Programmable Alarm setpoint
  • Special custom functionality
  • Low or High power internal Alarm relay
  • Variety of temperature sensors
  • Programmable operating features
  • Red, green or blue LED display
  • Additional input for external contact
  • Additonal input for second temp. sensor
  • Supply and Alarm can be different voltage
  • Custom designed face label
Temperature Sensor Probes
Temperature sensor probes for Digital Thermometer Digital Thermometer Semi Flush mounting Digital Thermometer flush mounting

Examples of available models
Wiring e​xtendable
up to 500 ft ( 150M)

Semi-Flush face digital thermometer installation
in wall or panel
Flush face digital thermometer installation
in wall or panel
Temperature Sensor Protection
Mounting Guard for Temperature Sensor probes Remote ON - OFF button Plastic guard for temperature sensor probes Temperature sensor with flange

Optional Plate-Guard
for standard sensor probes
Plastic model PPP-4
and SS model PPS-4

Optional Plastic Guard
for standard sensor probes
Model PG-5

Temperature Sensor
with Flange
Model PPB-1
Remote Control button

SDM-4 Digital Thermometer wiring examples

More SDM-4 Thermometer Wiring Examples

Digital Thermometer simple wiring for up to 30Amp, 250V loads Digital Thermometer basic wiring for Alarm load up to 30Amps, 250V
Simple SDM-4 thermometer wiring
for alarm load up to 30Amp
Basic SDM-4 thermometer wiring
for alarm load up to 30 Amps
Digital Thermometer wiring with Alarm contactor for very high loads Thermometer wiring with alarm buzzer
SDM-4 thermometer wiring
with Alarm buzzer
Extended SDM-4 thermometer wiring
for very high power ALARM loads
using external contactor
Digital Thermometer wiring with low voltage supply and for very high power loads Digital Thermometer simple wiring with two temperature sensors
Special SDM-4 thermometer wiring
for alarm load up to 30Amp
and with two temperature sensors
Extended SDM-4 thermometer wiring
for very high power alarm loads using external contactor
and with separate low voltage supply


Download SDM-4 Thermometer Specifications

SDM-4 is a digital temperature monitor with optional, programmable alarm capabilities.
It has an internal, accurate temperature test processor, that is self-calibrating and does not require any maintenance or adjustments.
The large 3-digit LED display shows current temperature readings, alarm status and other indications of operation. 
The LED display can be ordered in RED, GREEN or BLUE color.
The thermometer can also record the highest and lowest temperature values, and store them in internal memory for display, if necessary.
As another option, the thermometer can control an on-board alarm buzzer or relay, if it's necessary to activate other external devices at the alarm event. The relay can be either a hig power type with contacts rated for up to 30Amp, 250Vac load max. or a low power relay to switch loads of up to 1Amp, 250Vac max.
The high power or the optional low power relay contacts can be wired up to control Heaters, Coolers, HVAC and other loads like Fans, Motors, Pumps, etc...
The relay contacts can be wired up as completely isolated from the controller's supply, so the supply voltage can be different than the voltage on the load.
To switch very high loads, the relay contacts can also be wired up to control the coil of an external contactor.
Thermometer models available with an optional, additional, dry contact input for external control switch or other applications, like for instance to review the alarm settings or the min/max temperature memory.
Also, an additional, second temperature sensor can be installed for special applications like temperature difference monitoring or to display the temperature for two separate locations.
A variety of the operating and control configurations, temperature ranges and limits are also programmable.
Customized face plates are available on request.
Note, that SDM-4 thermometers are designed to eliminate almost completely the EMF ( Electro Magnetic Field ) radiation.


Digital Thermometer, Thermostat and Timer Numbering System