- Data Brochure
D 077
Indoor Sensor 077
The tekmar Indoor Sensor 077 includes a 10 kΩ thermistor mounted on a white enamel
steel plate to provide an accurate measurement of the indoor temperature. The 077 can be
mounted flush onto a standard duplex electrical box. Wiring enters from the back. The 077
can be connected to a 10k Room Temperature Unit (RTU) for remote temperature sensing.
05/07
Installation - Indoor Sensor 077
STEP ONE
Check the contents of this package. If any of the contents listed are missing or damaged,
please contact your wholesaler or tekmar sales representative for assistance.
Type 077 includes: •• One Indoor Sensor 077 •• One Data Brochure D 077 •• Two 6-32 x 3/4”
screws •• Two 6-32 x 1/2” screws
STEP TWO
Remove the two front screws from the face plate and pull the support plate from the
back of the sensor. Ensure the support plate screws do not fall off as the support plate is
removed.
STEP THREE
• The Indoor Sensor should be installed on an interior wall of the desired zone to be
controlled. Do not mount the 077 in a location that may be affected by localized heat
sources or cold drafts. It may be necessary to install a draft barrier and / or insulation
behind the enclosure in order to prevent air from blowing through the wiring hole and
affecting the Sensor reading.
MOUNTING THE SENSOR
REMOVING THE FRONT COVER
MOUNTING THE SUPPORT PLATE
• Mount the support plate to the
electrical box using the two support
plate screws provided.
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STEP FOUR
Run two conductor 18 AWG or similar wire between the Indoor Sensor and the terminals
on the tekmar control. Insert the wires through the hole provided in the back of the indoor
sensor enclosure and connect them to the indoor sensor terminal block. Do not run the wires
parallel to telephone or power lines. If the indoor sensor wires are located in an area with
strong sources of electromagnetic noise, shielded cable or twisted pair should be used or
the wires can be run in a grounded metal conduit. If using shielded cable, one end of the
shield wire should be connected to the Com-Sen terminals on the control and the other end
should remain free. The shield must not be connected to earth ground. Follow the sensor
testing instructions in this brochure and connect the wires to the control.
WIRING THE INDOOR SENSOR
STEP FIVE
Place any extra sensor wire into the electrical box. Secure the front plate of the Indoor
Sensor 077 to the support plate using the two front screws. Ensure the wiring is not pinched
or crushed when replacing the front plate.
INSTALLING THE FRONT COVER
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 temperature must be measured
with either a good quality digital thermometer, or if a thermometer 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 resistance of
the sensor at the control. The wires from the sensor must not be connected 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.
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