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Install The Enclosure
• Ensure that the pump wires are neatly tucked inside
the electrical box.
• Using 2 of the 4 holes in the back of the enclosure, se-
curely fasten it to the electrical junction box with 2 #10
screws as shown in Figure 5.
Low Voltage Wiring
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External Power Supply
It is strongly recommended that a transformer with an in-line
fuse be used in order to protect the transformer from high
currents. The tekmar Transformer 009 includes a fuse.
• Connect the 24 V (ac) leads from the transformer to the
C and R terminals marked "Input Power" on the 402.
tN2 Thermostats
The 402 is designed to operate with tekmarNet
They provide the heating and cooling control for each zone,
and communicate with any other tekmarNet
the system.
• Connect the tN2 terminals from each thermostat to the
corresponding tN2 terminals for each zone on the 402.
Zone Valves
• Wire the zone valves to the C and Vlv terminals on the
402.
• End switches on zone valves are not required when
using the 402.
tN4 Expansion Terminals
The 402 uses the Expansion tN4 and C terminals to
communicate with additional thermostats, setpoint controls,
and other tekmarNet
devices. There are two sets of tN4
®
and C terminals on the 402.
Boil Exp.
To add additional boiler water temperature zones (typically
baseboard or fan coil zones) to the system, install a
tekmarNet
Wiring Center.
®
• Connect the tN4 and C Boil Exp. terminals on the 402
to the corresponding tN4 and C Expansion terminals
on the external Wiring Center.
Mix Exp.
The 402 has the capacity to expand the number of mixing
zones in the system beyond the four on board zones. To
add additional mix water temperature zones (typically
radiant floor zones) to the system, install a tekmarNet
Wiring Center.
• Connect the tN4 and C Mix Exp. terminals on the 402
to the corresponding tN4 and C Expansion terminals
on the external Wiring Center.
© 2016
402_D - 05/16
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2 Thermostats.
®
device on
®
Figure 5
Domestic Hot Water (DHW) or Setpoint Call
When the control receives a DHW Call or Setpoint Call for
heat it will override Outdoor Reset and Indoor Feedback
and operate the boiler to heat the DHW tank or the Setpoint
equipment.
• To create a DHW call, wire a dry contact OR apply 24
V (ac) to the DHW call terminals.
• To create a Setpoint call, wire a dry contact OR apply
24 V (ac) to the Setpoint call terminals.
Wiring the Boiler
The 402 can operate a single modulating boiler, single
on-off, or a single two-stage on-off boiler.
On/Off Boiler
• Connect the Boiler Stage 1 terminals on the 402 to the
T-T (or R-W) terminals on the boiler.
• If required, connect the Boiler Stage 2 terminals on the
402 to the second stage T-T (or R-W) terminals on the
boiler.
Modulating Boiler
• Wire the Mod (dc/mA) positive (+) and negative (-) ter-
minals on the 402 to the input signal terminals on the
boiler. Correct polarity of the wires is important.
• In some cases, the modulating boiler also requires
contact closure on the T-T terminals to fire the boiler. If
required, connect the Boiler Stage 1 terminals on the
402 to the T-T (or R-W) terminals on the boiler.
Floating Action Terminals
Applications that use a floating action mixing valve actuator
(tekmar type 741) will use the Floating Action Opn, Cls, and
C terminals. This is a powered output (24 V (ac)).
• Wire the Opn, Cls, and C terminals on the 402 to the
open, close, and C terminals on the floating action
actuator.
Proportional Mixing (0-10 V (dc) or 4-20 mA)
Applications that use a proportional mixing valve actuator
®
will use the Mod (dc/mA) terminals. Proportional mixing can
only be used when a modulating boiler is not installed.
• Wire the Mod positive (+) on the 402 to the positive (+)
terminal on the actuator.
• Wire the Mod negative (-) on the 402 to the negative (-)
or common terminal on the actuator.
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