Figure 3: System 450 Reset Control System Example for a single boiler with a primary on/off boiler loop pump,
variable speed secondary loop pump, and a heated water modulating supply valve.
Note:
In 120VAC applications, L1 must be the hot wire and L2 must be the neutral or common wire.
Callout
Description>
1
A99 Temperature Sensor: Boiler supply water sensor, Sn-2, in Setup UI
2
Valve output temperature sensor Sn-3 in Setup UI.
3
A99 Temperature Sensor: Master Sensor for outdoor air, Sn-1, in Setup UI.
4
Active or passive sensor jumpers. All jumpers are set to passive by default. Note: Jumpers are only present in version 1.
5
Boiler on or off control circuit (24 to 240 VAC)
6
Boiler loop pump control circuit (24 to 240 VAC)
7
Secondary loop pump speed (0 to 10 VDC)
8
Mixing valve with 120F° setpoint (0 to 10 VDC)
9
Mixing valve with 120F° setpoint (0 to 10 VDC)
10
Relay Output 1
11
C450RCN-1 Reset Control Module
12
Relay Output 2
13
C450YNN-1 Power Module
14
Analog Output 3
15
C450SQN-1 Expansion Module
16
Analog Output 4
Table 1: System 450 terminal wiring information
Label
Terminal function
Wire sizes
24V
Accepts 24 VAC supply power, when a C450YNN power module is not connected, and provides power
terminal for 24 VAC (humidity) sensors.
5V
Provides 5 VDC power for active sensors.
Sn-1, Sn-2, Sn-3
Accepts passive or active (0-5 VDC) input signals from sensors.
In System 450 reset control systems, Sn-1 is the Master sensor (typically an outdoor air temperature sensor)
and Sn-2 is the controlled loop sensor (a temperature or humidity sensor).
Note:
Jumpers are only present in Version 1.
You must position the Active/Passive Sensor Jumper (Figure 4 and Figure 5) correctly for each sensor in
your control system before operating the system. See
Setting active/passive sensor jumpers
information.
C (Three Terminals)
Provide low-voltage common connections for 24 VAC power and passive or active sensors connected to the
5V, Sn1, Sn2, and Sn3 terminals.
The three C terminals are connected internally and can be connected to ground in the field.
0.08 mm
2
to 1.5 mm
2
28 AWG to 16 AWG
System 450 Series Reset Control Modules with Real-Time Clock and Relay Output Installation Guide
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