MACH
®
Gas Fired Boiler
47
5.6.2 Terminal Block Assignments – Low Voltage (Less than 32VAC) Circuit (TB1)
Terminal Number
Label
Description
1
ENABLE / DISABLE
Boiler Enable, Contact Closure.
DO NOT ENERGIZE.
2
ENABLE / DISABLE
3
EXTERNAL INTERLOCK
External Limit, Contact Closure.
DO NOT ENERGIZE.
4
EXTERNAL INTERLOCK
5
OUTDOOR TEMP SENSOR Outdoor temperature sensor
6
OUTDOOR TEMP SENSOR
7
DHW STAT OR SENSOR
Domestic Hot Water sensor or thermostat
8
DHW STAT OR SENSOR
9
HEADER TEMP SENSOR
Header temperature sensor
10
HEADER TEMP SENSOR
11
DHW FLOW SWITCH
Domestic Hot Water flow switch output
12
DHW FLOW SWITCH
COMMON
DHW flow switch closes and indicates potable water
flow/usage
13
0-10V ANALOG INPUT
Variable Input (VDC) for remote control of boiler (+)
14
0V ANALOG INPUT
0V for use with TB1-13 (-)
15
For Future Use
Not Used
16
For Future Use
17
MODBUS COM 1A
Modbus connection to boiler
18
MODBUS COM 1B
19
CASCADE A TO A
Cascade connection between boilers
20
CASCADE B TO B