Patterson-Kelley STORM ST-2500 Installation & Owner's Manual page 28

HDR Temp Sensor – TB1-7 and TB1-8 can be used to connect a remote header temperature sensor,
installed in the primary hydronic system piping, downstream of all the boilers. This temperature sensor
must be a 2-wire 12kΩ NTC thermistor. This circuit is energized by the boiler with a 5VDC potential.
DHW Stat/Sensor – TB1-9 and TB1-10 can be used to connect either an aquastat or remote DHW
temperature sensor installed in a domestic hot water storage tank. If using an aquastat, use a SPST
normally-closed, break on rise type with either a fixed or adjustable deadband above and below the
setpoint. Alternatively, if using a temperature sensor, it must be a 2-wire 12kΩ NTC thermistor and be
of sufficient length to measure an accurate storage tank temperature. This circuit is energized by the
boiler with a 5VDC potential.
Outdoor Temp Sensor – TB1-11 and TB1-12 can be used to connect an outdoor air temperature
sensor which allows the NURO control to be programmed to run an outdoor air schedule. The outdoor air
temperature sensor must be a 2-wire 12kΩ NTC thermistor and should be installed on the North face of
the building and shielded from direct sunlight exposure. This circuit is energized by the boiler with a
5VDC potential.
Night Setback – TB1-13 and TB1-14 can be used to connect a day/night or occupancy timer. Closure
of the Night Setback circuit enables the Night Setback mode which reduces the boiler's operating
setpoint. Opening this circuit resumes normal operation. This circuit is energized by the boiler with a
5VDC potential, so the contacts on the day/night timer must be rated for minimum 5VDC.
4-20mA Analog Output – TB1-15 and TB1-16 provide a 4-20mA analog output signal which tracks the
boiler's firing rate. When operating at full power (maximum firing rate), the boiler will provide a 20mA
output. When operating at minimum power (minimum firing rate), the boiler will provide a 4mA output.
Ground – TB1-17 provides an equipment (frame) ground connection for input, output, or
communication connections. For independently powered control devices, it may be necessary to
create a common ground.
Cascade Shield & Cascade – TB1-18, TB1-19, and TB1-20 can be used to setup a cascade system
with multiple STORM boilers with NURO controls. Terminals TB1-19 and TB1-20 are reserved for the
cascade communication between the master and member boilers. Terminal TB1-18 should be used to
connect the cascade communication wiring shield between all boilers. The cascade and shielding must
be wired from the master boiler to each individual member boiler in a daisy-chain fashion.
NOTE: Only ground the Cascade shield wire at the master boiler.
MODBUS COM & MODBUS Shield – TB1-22, TB1-23, and TB1-24 can be used to integrate the boiler
with a Building Management System (BMS), Protocol Converter, or other device capable of RS-485 2-
wire MODBUS communication. Terminals TB1-22 and TB1-23 are reserved for MODBUS and terminal
TB1-18 provides a connection for the MODBUS communication wire shield.
NOTE: Only ground the MODBUS shield wire at the master boiler.
ECOM 1, 2 & 3 – TB1-25, TB1-26, and TB1-27 can be used to connect a wireless outdoor air
temperature sensor. The wireless receiver should be installed at or near the boiler, and the wireless
temperature sensor should be installed on the North face of the building and shielded from direct
sunlight exposure.
Revised: June 26, 2020
Released: June 26, 2020
© Patterson-Kelley 2020
All Rights Reserved.
TM
P-K Storm Gas Fired Boiler
Technical Service 1.877.728.5351
2691000273 P-K Storm ST2500-ST4000
Installation and Owners Manual Rev A.docx
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