Install Instructions

5 Electrical connections
38
Installation & Service Manual
13. Replace the side access panel.
14. Turn ON the main electrical power and the main manual
gas shutoff to the appliance.
Wiring of Outdoor Air Sensor
Follow the guidelines in this section when wiring remote
sensors. Use shielded, 2-wire twisted pair cable. Take care
to correctly wire sensors to the unit. Erratic temperature
readings can be caused by poor wiring practices. If the
outdoor air sensor is unable to provide input to the
control, the boiler will default to the maximum set point.
For proper boiler operation it is important to follow all
wiring guidelines.
1. Turn OFF the main electrical power and the main
manual gas shutoff to the appliance.
2. Remove the upper front door panel from the appliance to
gain access to the temperature control.
3. Locate the outdoor air temperature sensor provided
in the kit. Determine the location of the remote sensor
and measure the amount of wire needed to connect
the sensor to the thermostat. The sensor should be placed
on a north wall, under the eve of the roof. Make sure the
housing is out of direct sunlight.
4. Do not route temperature sensor wiring with building
power wiring.
5. Do not locate temperature sensor wiring next to control
contactors.
6. Do not locate temperature sensor wiring near electric
motors.
7. Do not locate temperature sensor wiring near welding
equipment.
8. Make sure good mechanical connections are made to
the sensor, any interconnecting wiring and the
controller.
9. Do not mount sensor with lead wire end pointing up in
an area where condensation can occur.
10. Use 18 gauge or larger shielded, twisted pair cable
to connect the sensor to the control. This provides
protection against some types of electrical
interferences.
11. Remove the cover of the outdoor air temperature
sensor and route the wires through either the bottom
or the back of the sensor. Connect the wires to the
sensor and replace the cover (FIG. 5-8).
12. Run the shielded sensor wiring through the access hole
located on the back of the unit to CN11 on the upper
control board TST20036-2.
IMG00276
ROUTE TO CN11
ON TST20036-2
OUTDOOR AIR
RESET SENSOR
(TST2311)
Figure 5-7_Outdoor Air Temperature Sensor (TST2311)
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 18 AWG two conductor
(18/2). Use shielded wire.
Installation of System Sensor
1. Turn OFF the main electrical power and the main manual
gas shutoff to the appliance.
2. Remove the side access panel from the appliance to gain
access to the thermostat.
3. Locate the sensor provided in the kit. Determine the
location of the remote sensor and measure the amount of
wire needed to connect the sensor to the thermostat. See
Wiring of the Outdoor Air Sensor for guidelines.
4. Use twisted pair wire, minimum 18 gauge or larger.
Ensure all wire insulation is trimmed to reveal at least 3/8"
of exposed wire.
5. Connect the measured wire to the sensor wire using wire
caps. Install .250 x .032 insulated female quick connect
terminals to the end of the wires. Feed the wires through
the access hole located on the back of the unit and secure
the connectors to the thermostat connections (SYS/TANK)
CN5 and CN6 located in the upper right-hand of the
thermostat.
6. Turn on the electrical power and the main manual gas
shutoff to the appliance.
7. Replace the side access panel.
8. Fire the appliance and resume operation.
IMG00279
ACCESS
HOLE
CONNECT
OUTDOOR AIR
SENSOR
AND TANK
AQUASTAT
TO TST20036-2
CONNECT
SYSTEM
SENSOR TO
TST20036-1
Figure 5-8_Installation of Remote Sensors