Lochinvar 402 - 2072 operation manual Wiring of the cascade, 4_LowVoltage Field Wiring Connections

5 Electrical connections

Wiring of the cascade

When wiring the heaters for Cascade operation, select one heater as the Leader. The remaining heaters will be designated as Members. See page 50 Configuration of the Cascade for a detailed explanation of this procedure.

On boilers, connect the system supply sensor and outdoor air sensor (if used) to the Leader boiler. The location of the system supply sensor should be downstream of the boiler connections in the main system loop (FIG.’s 4-3 and 4-6). The system supply sensor should be wired to the low voltage connection board at the terminals marked for the system supply sensor (see FIG. 5-4). The Leader control will use the water temperature at the system supply sensor to control the operation of the Cascade.

If outdoor air reset is desired, the outdoor air sensor should be wired to the low voltage connection board at the terminals marked for the outdoor air sensor (FIG. 5-4). If the outdoor air sensor is connected, the Leader control will calculate the water temperature set point based on the programmed reset curve parameters. If the outdoor air sensor is not connected, the Leader control will maintain the space heating (SH) set point that is programmed into the control.

If a Thermostat, Zone Control enable output, or Building Management System enable output are available, it should be wired to the low voltage connection board on the Leader boiler at the Staging S1 terminals. If the boilers are to run continuously, leave the jumper wire between these terminals. This will initiate a call for heat on the Cascade. Also, leave the jumpers on the Staging S1 terminals of all the Member heaters. This will allow them to run independently should the Leader heater fail.

Installation & Operation Manual

Figure 5-4_Low Voltage Field Wiring Connections

TO MONITORING DEVICE	1	ALARM
	2	CONTACTS
TO MONITORING DEVICE	3	RUN-TIME
	4	CONTACTS
	5	OPEN	3-WAY	VALVE
THREE WAY	6	CLOSE
VALVE	7	COM
	8	S1
	S1	S1
	9
	10	S2
EXTERNAL	S2	S2	STAGING
	11
STAGING	12	S3
SEQUENCER
	S3	S3
LOUVER	13
PROVING	14	S4
SWITCH	S4	S4
	15

		16	LOUVER
		17	PROVING SW
LINE		18	LOUVER
TO LOUVER		19	RELAY COIL
DHW TANK		20	TANK
		21	AQUASTAT
THERMOSTAT			CN3
10K-TANK		22	TANK
SENSOR		23	SENSOR
FROM	A	24	SHIELD	CASCADE
TO NEXT
PREVIOUS		25	A
HEATER	B
	A	26	B
HEATER	B	27	SHIELD
		28	+ 0-10V
		29	- BMS IN
EXTERNAL		30	+ 0-10V
SEQUENCER/		31	- RATE OUT
BUILDING		32	SHIELD
AUTOMATIC				MODBUS
CONTROL		33	A
		34	B
		35	SHIELD
			CN2

On water heaters, connect the tank thermostat or BMS enable output to the low voltage connection board on the Leader heater, at the terminals marked for the tank Aquastat. If a tank sensor is used, connect this sensor to the low voltage connection board on the Leader heater, at the terminals marked for the tank sensor.

Communication between the Leader heater and the Member heaters is accomplished by using shielded, 2-wire twisted pair communication cable. Connect one of the twisted pair wires to terminal A on each of the low voltage connection boards, and the other wire of the twisted pair to terminal B on each of the low voltage connection boards. Connect the shield wire to the shield ground terminal on all of the heaters. If more than two heaters are on the Cascade, daisy chain the wiring from the Cascade terminals on the second heater to the Cascade terminals on the third heater, then from the third to the forth, and so on. The connections can be made in any order, regardless of the addresses of the heaters. Try to keep each cable as short as possible.

OUTDOOR

AIR SENSOR

SYSTEM SUPPLY

SENSOR

SYSTEM RETURN

SENSOR

PUMP SPEED	0-10VDC
INPUT	COMMON

(BOILER ONLY)

OUTDOOR

SENSOR

SYS SUPPLY

SENSOR

SYS RETURN

SENSOR

+ 0-10V SYS

- PUMP IN

CN2

46