7 Field wiring (continued)
Auxiliary switch 1 & 2
Additional field supplied limit controls may be connected to the auxiliary switch inputs. If additional limit controls fail or open, it will result in a manual reset lockout.
System supply sensor
1.By installing the system supply sensor into the supply of the primary loop, the temperature of the system supply can be controlled. The SMART TOUCH control automatically detects the presence of this sensor, and controls the boiler firing rate to maintain the system supply temperature to the set point.
| NOTICE | DO NOT INSTALL THE SYSTEM |
| SUPPLY SENSOR INTO THE SYSTEM |
| |
| | RETURN. |
2.For system supply sensor wiring information reference (FIG. 7-3).
Unless a firing rate is being provided by NOTICE a BMS system, a system supply sensor (factory supplied) MUST BE installed with Primary/Secondary piping systems
for proper boiler operation.
Boiler management system
1.An external control may be connected to control either the firing rate or the set point of the boiler. Connect the 0 - 10 VDC terminals to the 0 - 10 VDC output of the external control. The SMART TOUCH control can be enabled using the Enable output (see page 38) or using the voltage applied to the 0 - 10 VDC input. Reference the Crest Service Manual for more details.
2.Make sure terminal #34 on the Low Voltage Connection Board is connected to the (-) or COM output terminal of the external control, and 0 - 10 VDC terminal #33 is connected to the 0 - 10 VDC terminal of the external control.
Runtime contacts
The SMART TOUCH control closes a set of dry contacts whenever the burner is running. This is typically used by Building Management Systems to verify that the boiler is responding to a call for heat.
Alarm contacts
The SMART TOUCH control closes another set of contacts whenever the boiler is locked out or the power is turned off. This can be used to turn on an alarm, or signal a Building Management System that the boiler is down.
System return sensor
1.Install the system return sensor into the return of the primary loop.
2.Connect the terminals to the system return sensor as shown in FIG. 7-3.
Installation & Operation Manual
Wiring of the cascade
When wiring the boilers for Cascade operation, select one boiler as the Leader boiler. The remaining boilers will be designated as Members. See page 45 “Configuration of the Cascade” for a detailed explanation of this procedure.
Connect the system supply sensor, system return sensor and outdoor air sensor (if used) to the Leader boiler.
| NOTICE | Unless a firing rate is being provided by a |
| BMS system, a system supply sensor (factory |
| |
| | supplied) MUST BE installed with Primary/ |
| | Secondary piping systems for proper boiler |
| | operation. |
The location of the system supply sensor should be downstream of the boiler connections in the main system loop (FIG.’s 5-5 and 5-6). The system supply sensor should be wired to the Low Voltage Connection Board at the terminals marked for the system supply sensor (see FIG. 7-3). 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 on the Leader boiler (FIG. 7-3). 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 fixed water temperature set point that is programmed into the control.
If a Thermostat enable output is available, it should be wired to the Low Voltage Connection Board on the Leader boiler at the terminals marked Enable (FIG. 7-3). If the boilers are to run continuously, connect a jumper wire between the 7 and 8 terminals at the Enable input. This will initiate a call for heat on the Cascade. If the SMART TOUCH control is being controlled by a Boiler Management System (BMS), a call for heat may be initiated by the voltage applied to the BMS 0 - 10 VDC input instead.
Communication between the Leader boiler and the Member boilers is accomplished by using shielded, 2-wire twisted pair communication cable. Connect one of the twisted pair wires to Cascade terminal A on each of the Low Voltage Connection boards, and the other wire of the twisted pair to Cascade terminal B on each of the Low Voltage Connection Boards. Connect the shield wires to one of the Cascade shield ground terminals on the Low Voltage Connection Boards (FIG. 7-3). If more than two boilers are on the Cascade, daisy chain the wiring from the Cascade terminals on the second boiler to the Cascade terminals on the third boiler, then from the third to the forth, and so on. The connections between boilers can be made in any order, regardless of the addresses of the boilers. Try to keep each cable as short as possible.
37 
