Patterson-Kelley P-K STORM ST-1250 Installation & Owner's Manual page 25

NEUTRAL – Connect the neutral lead of the 208-240VAC, single phase, 60Hz electrical service to the
TB2-3 terminal.
GROUND – Connect the ground lead from the electrical service to the TB2-4 terminal.
Start Interlock #2 –
The Start Interlock #2 TB2-5 and TB2-6 terminals are in series with Start Interlock
#1 and provide additional connection points for auxiliary safety devices. This circuit is energized with
120VAC, so the contacts on any auxiliary safety devices must be rated for minimum 120VAC.
Start Interlock #1 –
The Start Interlock #1 TB2-7 & TB2-8 terminals can be used for auxiliary safety
devices such as damper limit switches, control valve limit switches, emergency stop buttons, and low
water cutoff devices. This circuit is energized with 120VAC, so the contacts on any auxiliary safety
devices must be rated for a minimum of 120VAC. The appliance ships with a factory-installed jumper
across Start Interlock #1 and Start Interlock #2 terminals. Remove the jumper(s) if using any auxiliary
safety devices.
NOTE: The Start Interlock circuit must close within 5 minutes of a call for heat. Failure to close the
Start Interlock circuit will cause the appliance to lockout on alarm.
Auxiliary Input #1 –
The TB2-11 & TB2-12 terminals are reserved for future use. This circuit is
energized with 120VAC
Air Damper Interlock – The Air Damper Interlock TB2-13 & TB2-14 terminals
end limit switch on a motorized air damper. This circuit is energized with 120VAC, so the contacts on
the end limit switch must be rated for minimum 120VAC. The appliance ships with a factory-installed
jumper across the Air Damper Interlock terminals. Remove the jumper if connecting a motorized air
damper with end limit switch.
NOTE:
The boiler ships with a factory-installed jumper across the Air Damper Interlock terminals.
Remove the jumper if connecting a motorized air damper with end limit switch.
Ground – Grounding connection for auxiliary safety/limit devices on terminal TB2-15.
NOTE: This ground terminal is connected to the TB2 sheet metal and is not common with the
appliance's electrical service ground.
Relay A, B, C & D – User-configurable relay outputs A (TB2-22 & TB2-23), B (TB2-20 & TB2-21), C
(TB2-18 & TB2-19) & D (TB2-16 & TB2-17). The normally-open contacts on these relays have a
maximum voltage rating of 240VAC and maximum current capacity of 1/2 Amp.
NOTE: Refer to 6.1, for proper
through D can be user-configured through the NURO
such as the Comfort Heat (CH) pump, Domestic Hot Water (DHW) Pump, Air Damper, System
Pump, etc.
Master Alarm Relay – The Master Alarm Relay TB2-24 & TB2-25 terminals are normally-open dry
contacts that close in the event of an alarm output from the NURO control. The normally-open contacts
on this relay have a maximum voltage rating of 240VAC and maximum current capacity of 1/2 Amp.
Revised: October 2, 2019
Released: October 2, 2019
.
wiring and configuration of the electrical connections. Relays A
 Patterson-Kelley 2019
All Rights Reserved.
P-K Storm
Technical Service 1.877.728.5351
®
touch screen interface to control devices
2691000099 P-K Storm Installation and Owners
TM Gas Fired Boiler
allow for proof of open
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