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Installing the Outdoor Sensor
Note
The temperature sensor (thermistor) is built into the enclosure.
• Take the sensor cover off by sliding it upward relative to the sensor base.
• Use one round or pan head screw to attach the base of the sensor to the wall.
• The sensor is wall mounted and the wiring enters through the bottom of the enclosure. The
hole for the cable entry must face downward in order to prevent water from entering and filling
the enclosure.
• The sensor should be mounted on a wall which best represents the heat load on the
building (i.e. a northern wall for most buildings and a southern facing wall for buildings with
large south facing glass areas). The sensor should not be installed near 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.
• Install the Outdoor Sensor and run the wiring back to the control mounting location.
Installing the Supply Sensor and Boiler Sensor
Note
These sensors are designed to mount on a pipe or in a temperature
immersion well.
• The sensors can be strapped directly to the pipe using the cable tie
provided. Insulation should be placed around the sensors to reduce
the effect of air currents on the sensor measurement.
• The Boiler Sensor and the Supply Sensor should be placed down-
stream of a pump or after an elbow or similar fitting. This is especially
important if large diameter pipes are used because the thermal
stratification within the pipe can result in erroneous sensor readings.
Proper sensor location requires that the fluid is thoroughly mixed
within the pipe before it reaches the sensor.
STEP THREE
Wiring to the Zone Control
Connect the PC705-2 cable to the Add-On interface on the Taco Zone Control.
Ensure the Mode switch on the Zone Control is set to Reset if boiler control is
desired, or Normal if boiler enable is desired (refer to the Boiler Operation section).
Wiring the Sensors
Do not apply power to these terminals as this will damage the control.
Outdoor Sensor
Connect the two wires from the Outdoor Sensor directly to the Com — Out (1 and
3) terminals. The Outdoor Sensor measures the outdoor air temperature.
Supply Sensor
Connect the two wires from the Supply Sensor directly to the Com — Sup (1 and
2) terminals. The Supply Sensor measures the water temperature supplied to the
system.
Boiler Sensor (Optional)
Connect the two wires from the Boiler Sensor directly to the Com— Boil (1 and 4)
terminals. The Boiler Sensor measures the boiler supply water temperature.
Variable Speed Injection Pump
The PC705-2 can vary the speed of a permanent capacitor impedance protected
or equivalent pump motor that has a locked rotor current of less than 2.4 A. The
Taco "00" family of wet rotor circulators are suitable for the PC705-2. The variable
speed output must not be used on pumps which have a centrifugal switch. The
PC705-2 has an internal overload protection fuse which is rated at 2.5 A 240 V (ac).
This fuse is not field replaceable. Contact your sales representative for details on
the return and repair procedures if this fuse is blown.
Connect the black wire from the back of the control to the live (L) side of the 120
V (ac) power source. Connect one of the wires from the variable speed injection
pump to the blue wire from the back of the control. The other wire on the variable
speed injection pump must be connected to the neutral (N) side of the 120 V (ac)
power supply. Connect the green wire on the back of the control to ground.
Ground
(green)
Injection Pump
(blue)
Live Power (L)
(black)
System Pump
(Red)
4
2
Boil
Sup
1
Com
3
Out
3
2
Sup
Out
1
Com
4
Boil
3
2
Sup Out
1
Com
4
Boil
Cable Entry
Hole for
mounting screw
