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Sensors and Transducers Mounting • 3-9
outside and inside temperature to monitor supply and
return air temperature. When used in this application, the
sensors are supplied without enclosure covers. The sensors
should be mounted directly in the air stream of the supply
or return air duct. The sensors are not supplied with any
mounting hardware for this application.
3.5.6 Refrigeration System Tem-
perature Probes and Sensors
3.5.6.1 Location
Retail Solutions supplies several temperature monitor-
ing devices including bullet sensors, pipe mount sensors,
immersion probes, insertion probes, and sensors for high
temperature applications. Each of these sensors is gener-
ally installed on the system by the equipment manufac-
turer. If a device must be added to the system, refer to the
information supplied with the device and consult the
refrigeration equipment manufacturer. Table 3-1 lists some
typical sensor applications and the sensor or probe most
suited for that purpose.
3.5.6.2 Mounting Bullet and Pipe Mount
Sensors
Bullet or pipe mount sensors mounted on refrigerant
lines should be secured with a Panduit low temperature
cable tie, number PLT2S-M120, or equivalent. For pipe
mount sensors, the curved surface should be placed
against the pipe and the tie should be positioned in the
groove on the top surface of the sensor. A second tie
should be used to secure the lead to the pipe for additional
support.
Sensors located on refrigerant lines should be insulated
to eliminate the influence of the surrounding air. A self-
adhering insulation that will not absorb moisture is recom-
mended to prevent ice logging at the sensor location.
The sensor should be positioned on the side of the line
as shown in Figure 3-24.
3.5.7 Product Temperature
Probes
The product temperature probe is designed to be used
alongside food products in a refrigeration case or freezer.
The product probe uses a thermistor type temperature sen-
sor in a sealed, cylindrical container (approximately 16
oz.). A magnet is contained at the bottom the probe’s
enclosure to allow easy attachment to a side or bottom of a
refrigeration case.
3.5.8 Humidity Sensors and
Humidistats
3.5.8.1 Indoor RH Sensor
The indoor relative humidity sensor should be
mounted in a central location within the zone to be mea-
sured, away from doors, windows, vents, heaters, and out-
side walls that could affect temperature readings. The
sensor should be between four and six feet from the floor.
Note that this sensor generates a small amount of heat;
therefore, do not mount temperature sensors directly
above RH sensors.
Mount RH sensor (P/N 203-5751) as follows:
1. With a flat-head screwdriver, push down the
middle tab on the top of the sensor case and
pop the lid off to expose the circuit board.
2. Insert the flat-head screwdriver into the two
slots on either side of the top of the sensor
case and twist to separate the back plate from
the case.
3. Remove the knock-outs from the back plate
before mounting so wires may be threaded
through.
Application Sensor Type
Condenser Outlet (Drop Leg) High Temperature Bullet
Liquid (Manifold) Pipe Mount
Suction Temperature Pipe Mount
Discharge Air Bullet
Ambient Temperature (Outside) Bullet
Condenser Sump Insertion Probe
Defrost Termination Bullet
Table 3-1 - Sensor Application and Type
Figure 3-24 - Sensor Orientation