NTI Trinity Lx150 - Lead Lag Instructions

Lx Series Installation and Operation Instructions │Trinity Lx
51
11.0 LEAD LAG INSTRUCTIONS
Multiple Boiler Applications
The Lx controller has the internal capacity to stage or Lead-Lag up to 8 boilers configured in a cascade. This
Lead-Lag capability allows a designated “Master” boiler to communicate with and effectively control each
boiler in a multiple boiler system. This function is accomplished by “Daisy Chaining” a 3-wire cable between
each of the boilers and enabling the Master parameter in the boiler of your choice. The boiler with the Master
parameter enabled becomes the single point of contact for Central Heating, Domestic Hot Water and Outdoor
Reset settings and control. Use the instructions detailed in this section to set-up and install the cascade boiler
system; reference Appendix A – Controller and Touchscreen Display Instructions for details on more advanced
settings and for assistance with navigating the touchscreen display.
Lead Lag Instructions - Common
Plumbing – install as many as 8 Lx boilers in parallel in a primary/secondary plumbing configuration as
illustrated in Figure 11-1. Size common piping as per Table 11-1.
Boiler Pump – each boiler must have its own circulator (see Figure 11-1) which is controlled by its PUMP B
output; see Field Wiring Figures and Tables 12-1(a) and 12-1(b). The Boiler Pump must be sized according
to Table 10-4.
Communication Wiring – using 3-wire cable, daisy-chain terminals LL DATA +, LL DATA – and SENSOR
COM of each boiler in parallel; see Field Wiring Tables 12-2(a) and 12-2(b) and Figure 12-2.
System Sensor (Optional) – install a system sensor (NTI P/N: 84010) on the outlet (supply) pipe feeding the
heating system, see Figure 11-1. Wire the system sensor to SENSOR COM and SYSTEM (OD / SYS SENSOR
for Lx500-800 models) of the Master Boiler; see Field Wiring Tables 12-2(a) and 12-2(b) and Figure 12-2.
The system sensor automatically becomes the modulation sensor for the boiler system, i.e. the control attempts
to achieve setpoint temperature at the location of the sensor. If a system sensor is NOT used, at the Master
boiler set the applicable sensor input to Unconfigured as follows:
Configure – Sensor Configuration – S10 (J10-7) sensor [S5 (J8-11) sensor for Lx500-800 models]
Outdoor Sensor (Optional) – wire the outdoor sensor to SENSOR COM and OD SENSOR (OD / SYS SENSOR
for Lx500-800 models) of any one of the boilers in the cascade (for Lx500-800 models, outdoor sensor must
be connected to a non-Master boiler); see Field Wiring Tables 12-2(a) and 12-2(b) and Figure 12-2. Note:
only one outdoor sensor is needed for the multiple boiler system.
Modbus Address – assign a unique MB2 Modbus Address to each boiler in the cascade. Access the MB2
Modbus Address setting via the System Identification & Access menu as follows:
Configure – System Identification & Access – MB2 Modbus Address
Master Enable – choose one (and only one) boiler in the cascade to be the Master, this boiler will receive all
control wiring and will be used for setting control parameters (see steps below). On this one boiler, set Master
enable equal to Enabled via the Lead Lag Master Configuration menu, accessed as follows:
Configure – Lead Lag Master Configuration – Master enable
Table 11-1 Minimum Pipe Sizes for Multiple Boiler Applications
# of
Units
Lx150/150E
Lx200
Lx300
Lx400
Lx500
Lx600
Lx700
Lx800
2
1-1/2"
2"
2”
2-1/2"
2-1/2”
3”
3”
3"
3
2"
2"
2-1/2”
3"
3”
3”
4”
4"
4
2"
2-1/2"
2-1/2”
3"
4”
4”
4”
4"
5
2-1/2"
2-1/2"
3”
4"
4”
4”
4”
5"
6
2-1/2"
3"
3”
4"
4”
4”
5”
5"
7
2-1/2"
3"
4”
4"
4”
5”
5”
5"
8
2-1/2"
3"
4”
4"
5”
5”
5”
5"