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3.4.4
Low Voltage (TB1) Terminal Block
Enable/Disable– TB1-1 and TB1-2 are used for enabling the boiler. Closing this circuit allows the boiler to run.
Opening this circuit prevents the boiler from running. This circuit is energized by the boiler. It has a 24 VAC potential.
Devices connected to these terminals must be rated for 24 VAC
Note: This circuit will become unusable in certain CH modes and Cascade Master Modes dealing with 0-
10vdc.
External Interlock – TB1-3 and TB1-4 are used for attachment of an additional field safety device to the boiler control
circuit. Closing this circuit allows the boiler to run. Opening this circuit prevents the boiler from running. This circuit is
energized by the boiler with a 5 V potential. Devices connected to these terminals must be rated for 5 V.
Outdoor Temp Sensor – TB1-5 and TB1-6 are connected to the outdoor temperature sensor. The temperature
control must be programmed to run an outdoor air schedule. The outdoor air sensor and programming help are
available from the local Harsco Industrial, Patterson-Kelley Representative. This circuit is energized by the boiler with
a 5 V potential. The temperature sensor must be a NTC having 12 k @ 77°F.
DHW Stat/Sensor – TB1-7 and TB1-8 are connected to the DHW temperature sensor or thermostat. This circuit is
energized by the boiler with a 5V potential. The temperature sensor must be a NTC having 12 k @ 77°F.
Header Temp Sensor – TB1-9 and TB1-10 are connected to the header temperature sensor. This circuit is
energized by the boiler with a 5 V potential. The temperature sensor must be a NTC having 12 k @ 77°F.
DHW Flow Switch – TB1-11 is energized by the boiler with a 5 V potential. This circuit connects through a flow
switch on the domestic side of a domestic hot water system. The flow switch should close upon flow to provide a
closed circuit back to TB1-12.
Analog Input– Remote signal for controlling the boiler. The boiler can be operated in a remote setpoint or a remote
firing rate control mode. Input 0-10 VDC+ signal on TB1-13 only. The 0 VDC- Analog Input is provided on TB1-14.
The temperature control must be programmed to run with the analog input. (See the ENVI
Guide for more information)
MODBUS® – TB1-17 and TB1-18 are used for connecting a MODBUS® building management system. (See the
®
ENVI
Control Advanced Users Guide for more information)
Cascade – TB1-19 and TB1-20 are used to connect between boilers that are part of a Master/Member Network. Up to
24 boilers may be connected together. (See the ENVI
3.5
I
A
E
NLET
IR AND
XHAUST
3.5.1
Applicable Codes & Standards
CODES
United States:
NFPA 54/ANSI Z223.1
NFPA/ANSI 211
Canada
CAN/CSA B149.1
STANDARDS
UL 1738
ULC S636-95
Sheet Metal and
Air Conditioning Contractors National Association (SMACNA)
®
V
ENTING
National Fuel Gas Code
Chimneys, Fireplaces, Vents and Solid Fuel Burning Appliances
Installation Codes for Gas Burning Equipment
Venting Systems for Gas-Burning Appliances, Categories II, III, and IV
Standard for Type BH Venting Systems
Thermoplastic Duct Construction Manual
Control Advanced Users Guide for more information)
16
®
MACH
Gas Fired Boiler
®
Control Advanced Users
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