5 of 8
STEP THREE
Wiring to the Zone Control
Connect the PC702-1 cable to the Add-On interface on the Taco Zone Control. Ensure the
Mode
switch on the Zone Control is set
to
Reset
.
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 to the terminals
Com
—
Out
(5 and
7). The Outdoor Sensor measures the outdoor air temperature.
Boiler Sensor
Connect the two wires from the Boiler Sensor to the terminals
Com — Sup
(5 and 6).
The Boiler Sensor measures the supply water temperature going from the boiler to the
system.
Wiring the Boilers
The Stage 1 and Stage 2 terminals (1 & 2 and 3 & 4) are isolated outputs in the PC702-1.
There is no power available on these terminals from the control. These terminals are to
be used as a switch to either make or break the boiler circuit. When the PC702-1 requires
the boiler(s) to fire, it closes the contact between terminals 1 and 2 and/or 3 and 4.
DHW Demand
To generate a DHW demand, a voltage between 24 and 240 V(ac) must be applied across
the two DHW demand wires (black wires) coming from the back of the control. This can
be achieved by wiring these two wires in parallel to the DHW (priority) zone on the Taco
Zone Control.
Settings
Before adjusting the settings, read through the sequence of operation to ensure that you understand how the control operates. The
following page describes how to program these settings into the control once it has been powered up.
STEP FOUR
Boiler Starting Temperature (BOIL Start)
The
BOIL Start
setting is the starting supply water temperature of the reset ratio, and can be adjusted from 35 to 150
°
F (2 to 66
°
C).
This setting is typically set to the desired building temperature. In applications where fan coils are used, the
BOIL Start
may need to
be set higher to prevent cold drafts during mild outdoor conditions. If the building feels cool during mild outdoor conditions, the BOIL
Start setting should be increased.
Outdoor Starting Temperature (OUTDR Start)
The OUTDR Start setting is the outdoor temperature at which the starting temperature is supplied. The adjustment range is from 35
to 85
°
F (2 to 29
°
C). This setting is typically set to the desired building temperature.
Boiler Design Temperature (BOIL DSGN)
The BOIL DSGN setting is the water temperature required to satisfy the building heat loss during the coldest outdoor temperature.
This adjustment is typically dependent on the type of heating terminal used. The following are suggested settings for different terminal
units:
• Inslab Radiant ..................... 100 to 140
°
F (38 to 60
°
C)
• Radiant Baseboard ................. 130 to 160
°
F (54 to 71
°
C)
• Staple-up Radiant
.......... 130 to 160
°
F (54 to 71
°
C)
• Convective Baseboard
....... 160 to 190
°
F (71 to 88
°
C)
• Radiators ............................ 140 to 160
°
F (60 to 71
°
C)
• Fan Coil
.............................. 180
to 200
°
F (82 to 93
°
C)
Outdoor Design Temperature (OUTDR DSGN)
The OUTDR DSGN setting is the outdoor temperature used in the heat loss calculation. It is set to the typical coldest outdoor
temperature.
Boiler Minimum Supply Temperature (BOIL MIN)
Most boilers require a minimum operating temperature to prevent corrosion from flue gas condensation. The
Minimum Boiler
setting
should be programmed to the lowest supply water temperature at which the boiler can operate without causing the boiler flue gases
6
Sup
5
Out
7
Com
5
Out
6
Sup
7
Com
Zone 3 Zone 4
POWER
Zone 4
Zone 3
Zone 2
INPUT
120 VOLT CIRCULATORS
STOP
Refer servicing to qualified
personnel. Opening voids
warranty
.
To DHW
Pump
