Table of Contents
Advertisement
Relay A – User-configurable relay output #1 located on terminals TB2-22 & TB2-23. The normally-
open contacts on this relay have a maximum voltage rating of 240VAC and maximum current capacity
of 1/2 Amp.
Relay B – User-configurable relay output #2 located on terminals TB2-20 & TB2-21. The normally-
open contacts on this relay have a maximum voltage rating of 240VAC and maximum current capacity
of 1/2 Amp.
Relay C – User-configurable relay output #3 located on terminals TB2-18 & TB2-19. The normally-
open contacts on this relay have a maximum voltage rating of 240VAC and maximum current capacity
of 1/2 Amp.
Relay D – User-configurable relay output #4 located on terminals TB2-16 & TB2-17. The normally-
open contacts on this relay have a maximum voltage rating of 240VAC and maximum current capacity
of 1/2 Amp
.
Refer to Section
7.2
for proper wiring and configuration of the electrical connections.
Relays A through C can be user-configured through the NURO touch screen interface to control
devices such the Comfort Heat (CH) Pump, Domestic Hot Water (DHW) Pump, Air Damper, System
Pump, etc. Relay D cannot be used for Air Damper.
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 boiler control. The normally-open contacts
on this relay have a maximum voltage rating of 240VAC and maximum current capacity of 1/2 Amp.
3.3.4 Low Voltage (TB1) Terminal Block
Enable/Disable –TB1-1 and TB1-2 can be used to remotely enable or disable the boiler. The
functionality of these terminals is user-configurable through the NURO controls, but generally closure of
the Enable/Disable circuit provides a call for heat to the boiler. Opening this circuit prevents the boiler
from running.
The boiler ships with a factory-installed jumper across the Enable/Disable terminals. This circuit is
energized with a 24VAC potential, so the contacts on any remote enable devices must be rated for
minimum 24VAC.
4-20mA Analog Input – TB1-3 and TB1-4 can be used to provide a remote analog 4-20mA control
signal to the boiler. This analog signal can be used to change the boiler's operating setpoint or firing
rate.
Spare Analog Input – TB1-5 and TB1-6 are reserved for future use.
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 dead-band 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
potential.
5VDC
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
Revised: January 3, 2020
Released: January 3, 2020
NOTE
Patterson-Kelley 2020
All Rights Reserved.
®
P-K MACH
Technical Service 1.877.728.5351
1004905980 P-K MACH CM300-CM500&C750-C1050
Installation and Owners Manual (Rev F Jan-2020).docx
Gas Fired Boiler
Page 19
Hide quick links:
Advertisement
Table of Contents
