tekmar 256 Boiler Control - Manual (Page 10)

Note: The temperature sensor (thermistor) is built into the
enclosure.
Remove the screw and pull the front cover off the sensor
enclosure.
The sensor can either be mounted directly onto a wall or a
2” x 4” electrical box. When wall mounted, the wiring should
enter through the back or bottom of the enclosure. Do not
mount the sensor with the conduit knockout facing upwards
as rain could enter the enclosure and damage the sensor.
In order to prevent heat transmitted through the wall from
affecting the sensor reading, it may be necessary to install
an insulating barrier behind the enclosure.
The Outdoor Sensor should be mounted on a wall which
best represents the heat load on the building (a northern wall
for most buildings and a southern facing wall for buildings
with large south facing glass areas). The sensor should not
be exposed to heat sources such as ventilation or window
openings.
The sensor should be installed at an elevation above the
ground that will prevent accidental damage or tampering.
Mounting the Outdoor Sensor
Sensor with bottom
entry wiring Sensor with rear
entry wiring Sensor mounted
onto 2" x 4"
electrical box
Connect 18 AWG or similar wire to the two terminals provided in
the enclosure and run the wires from the sensor 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 or Com Sen terminal on the control
and not to earth ground.
Follow the sensor testing instructions in this brochure and
connect the wires to the control.
Replace the front cover of the sensor enclosure.
Wiring the Outdoor Sensor
Wires from outdoor
sensor to control
terminals
(Com Sen - Out Sen)
Sensor is built into
the enclosure
© 2011 D 256 - 07/11 10 of 20