Install Instructions

44
5 Electrical connections
Remote mounting of a sensor
You must mount the outside air temperature sensor outside
the building. To mount remote sensors, follow the guidelines
below. Take care to correctly wire sensors to the unit. Erratic
temperature readings can be caused by poor wiring practices.
Twist the wires between the unit and the remote sensor. Turn
wires at least three or four turns per linear foot of wiring. This
provides common mode rejection of some types of electrical
interferences.
1. Do not route temperature sensor wiring with building
power wiring.
2. Do not locate temperature sensor wiring next to control
contactors.
3. Do not locate temperature sensor wiring near electric
motors.
4. Do not locate temperature sensor wiring near welding
equipment.
5. Make sure good mechanical connections are made to the
sensor, any interconnecting wiring and the controller.
6. Do not mount sensor with leadwire end pointing up in an
area where condensation can occur.
Installation & Service Manual
Figure 5-13_Outdoor air reset chart example
Outdoor air Temperature sensor
The outside air temperature sensor will only be used for boiler
systems. The outside air sensor is optional. You must purchase
the sensor from the appliance manufacturer. The sensor comes
with a housing that helps protect the sensor from the elements.
Mount the air sensor housing under the eve of the roof. Make
sure the housing is out of direct sunlight. This will ensure that
the sensor will accurately read the true outdoor temperature.
For more information on mounting the sensor, see Remote
Mounting of a Sensor.
NOTICE
Ground the cable shield at the connection
to the boiler temperature control only. Do
not ground the shielded cable at the sensor
end.
To maintain temperature accuracy, sensor
wires should be at least 18 AWG, see Table
5C.
TABLE 5C
Remote Wire Connection
Wire Gauge Max. Allowable Length
12 GA 100 FT
14 GA 75 FT
16 GA 50 FT
18 GA 30 FT
7. Use shielded wiring to connect the sensor to the control
when the possibility of an electrically noisy environment
exists. Shielded cable is recommended on all cable runs of
more than 25 feet in length.