P-K Storm
TM
Gas Fired Boiler
Technical Service 1.877.728.5351
Revised: June 26, 2020
Released: June 26, 2020
©
Patterson-Kelley 2020
All Rights Reserved.
2691000273 P-K Storm ST2500-ST4000
Installation and Owners Manual Rev A.docx
Page 66
6.1 Terminal Block Assignments
Terminal Block Assignments
— Low Voltage (TB1) Terminal Block
Terminal Number
Label
Description
27
ECOM 3
Wireless Outdoor Air Receiver
26
ECOM 2
25
ECOM 1
24
MODBUS SHIELD
2-Wire MODBUS RS485 & Shield Terminal
23
MODBUS COM B
22
MODBUS COM A
21
MODBUS/CASCADE REF
Reference Terminal (Application Dependent)
20
CASCADE B TO B
2-Wire Cascade & Shield Terminal
19
CASCADE A TO A
18
CASCADE SHIELD
17
GROUND
Ground Terminal for I/O Devices
16
ANALOG OUTPUT [-]
4-20mA Analog Output Tracks Boiler Firing Rate
100% Firing Rate = 20mA, 1% Firing Rate = 4mA
15
4-20mA ANALOG OUTPUT [+]
14
NIGHT SETBACK
Contact Closure Enables Night Setback Operation
Open Circuit Disables Night Setback Operation
13
NIGHT SETBACK
12
OUTDOOR TEMP SENSOR
Outdoor Air Temperature Sensor for ODA Reset
Configurable for 10kΩ or 12kΩ Sensor
11
OUTDOOR TEMP SENSOR
10
DHW STAT / SENSOR
DHW Enable Circuit Configurable for SPST Break-on-
rise Aquastat, or 10kΩ or 12kΩ Tank Sensor
9
DHW STAT / SENSOR
8
HDR TEMP SENSOR
Hydronic Supply Header Temperature Sensor
Configurable for 10kΩ or 12kΩ Sensor
7
HDR TEMP SENSOR
6
SPARE ANALOG INPUT
Reserved for Future Use
5
SPARE ANALOG INPUT
4
ANALOG INPUT [-]
4-20mA Analog Input
Configurable for Setpoint or Firing Rate Control
3
4-20mA ANALOG INPUT [+]
2
ENABLE / DISABLE
Contact Closure Enables Comfort Heat Operation
Open Circuit Disables Comfort Heat Operation
1
ENABLE / DISABLE