4
Installation - Outdoor Sensor PM-070
Step Two
Wiring And Testing The Sensor
• Connect 18 AWG or similar wire to the two terminals provided in the enclosure
and run the wires from the PM-070 to the control. Do not run the wires parallel
to telephone or power cables. If the sensor wires are located in an area with
strong sources of electromagnetic interference (EMI), shielded cable or twisted
pair should be used or the wires can be run in a grounded metal conduit. If using
shielded cable, the shield wire should be connected to the Com terminal on the
control and not to earth ground.
• Follow the sensor testing instruction in this brochure and connect the wires to
the control.
• Replace the front cover of the sensor enclosure.
Sensor Testing Instructions
A good quality test meter capable of measuring up to 5,000 kΩ (1 kΩ = 1000Ω) is
required to measure the sensor resistance. In addition to this, the actual tempera-
ture must be measured with either a good quality digital thermometer, or if a ther-
mometer is not available, a second sensor can be placed alongside the one to be
tested and the readings compared.
First measure the temperature using the thermometer and then measure the resis-
tance of the sensor at the control. The wires from the sensor must not be connect-
ed to the control while the test is performed. Using the chart on the following page,
estimate the temperature measured by the sensor. The sensor and thermometer
readings should be close. If the test meter reads a very high resistance, there may
be a broken wire, a poor wiring connection or a defective sensor. If the resistance
is very low, the wiring may be shorted, there may be moisture in the sensor or the
sensor may be defective. To test for a defective sensor, measure the resistance
directly at the sensor location.
Do not apply voltage to a sensor at any time as damage to the sensor may result.
Wires from outdoor
sensor and sensor
common terminals on
Watts control
Sensor is built into
the enclosure
Slide cover
back over
base
S1
S1
Summary of Contents for PM-070
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