Trinity Lx
│
Plumbing and Wiring Instructions Water Heater Applications
12
Multiple Water Heater Applications
The Lx controller has the internal capacity to stage or Lead-Lag up to 8 water heaters configured in a cascade.
This Lead-Lag capability allows a designated “Master” water heater to communicate with and effectively control
each water heater in a multiple water heater system. This function is accomplished by “Daisy Chaining” a 3-
wire cable between each of the water heaters and enabling the Master parameter in the water heater of your
choice. The water heater with the Master parameter enabled becomes the single point of contact for settings and
control wiring. Use the instructions detailed in this section to set-up and install the cascade water heater 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
Plumbing
– install as many as 8 Lx water heaters in a parallel plumbing configuration as illustrated in Figure 2-3.
Size common piping as per Table 2-5.
Water Heater Pump
– each water heater must have its own circulator (see Figure 2-3) which is controlled by its
PUMP B
output; see
Field Wiring
Figures and Tables 3-1(a) and 3-1(b). The water heater pump must be sized
according to Table 2-4.
Communication Wiring
– using 3-wire cable, daisy-chain terminals
LL DATA +
, LL
DATA –
and
SENSOR
COM
of each water heater in parallel; see
Field Wiring
Tables 3-2(a) and 3-2(b) and Figure 3-2.
System Sensor
– a system sensor is
NOT
used in a water heater application, 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
]
Modbus Address –
assign a unique
MB2 Modbus Address
to each water heater 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) water heater in the cascade to be the Master, this water heater will
receive all control wiring and will be used for setting control parameters (see steps below). On this one water
heater, set
Master enable
equal to
Enabled
via the
Lead Lag Master Configuration
menu, accessed as follows:
Configure
– Lead Lag Master Configuration – Master enable
Tank Thermostat
– connect to
SENSOR COM
and
DHW
of the Master water heater; see
Field Wiring
Tables 3-
2(a) and 3-2(b) and Figure 3-2. Switch must be an isolated end switch (dry contact).
DHW Setpoint
– at the Master water heater only, set the
DHW setpoint
via the
Lead Lag Master Configuration
menu, accessed as follows:
Configure
– Lead Lag Master Configuration – DHW setpoint
DHW switch (Lead Lag)
– at the Master water heater only, set
DHW switch
equal to
DHW (S6) sensor shorted
via the
Lead Lag Master Configuration
menu, accessed as follows:
Configure
– Lead Lag Master Configuration – Advanced Settings – Domestic Hot Water – DHW switch
DHW enable (Local)
– at the Master water heater only, set
DHW enable
equal to
Disabled
via the
Domestic Hot
Water Configuration
menu, accessed as follows:
Configure
– Domestic Hot Water Configuration – DHW enable
Tank Sensor
– when operating in a cascade system, the water heater controls do not
support the use of a tank sensor; a tank thermostat (switch) must be used.
