Interlocks; Fault Relay (Nc, Com, & No); Auxiliary Relay Contacts (Nc, Com, & No) - Watts AERCO Benchmark BMK750 Installation And Start-Up Manual

Benchmark 750-6000 with Edge [i]: Install-Startup Manual
SECTION 2 – INSTALLATION

2.11.12 Interlocks

The unit has two interlock circuits for interfacing with Energy Management Systems and auxiliary
equipment such as pumps, louvers or other accessories. These interlocks are called the Remote
Interlock and Delayed Interlock (REMOTE INTL'K IN and DELAYED INTL'K IN in Figure 2-11).
Both interlocks, described below, are factory wired in the closed position using jumpers.
NOTE:
Both the Delayed Interlock and Remote Interlock must be in the closed position for the unit to fire.
Remote Interlock In (OUT & IN)
2.11.12.1
The remote interlock circuit is provided to remotely start (enable) and stop (disable) the unit if
desired. The circuit is 24 VAC and comes factory pre-wired closed (jumped).
Delayed Interlock In (OUT & IN)
2.11.12.2
The Delayed Interlock terminals can be used in one of two ways:
•
In conjunction with the optional external sequencing valve, a component of AERCO's on-
board Boiler Sequencing Technology (BST) solution (see section 2.14: Sequencing Isolation
Valve Installation and Section 7: Boiler Sequencing Technology in the Benchmark 750-6000
with Edge [i] Controller Operation Guide (OMM-0145. GF-218). A cable of the boiler's wiring
harness is connected to these terminals on all units; if BST is implemented, the other end of
that cable is connected to the sequencing valve.
•
If BST is NOT implemented, the second use is typically in conjunction with the AUXILIARY
RELAY CONTACTS described in section 2.11.14, below. This interlock circuit is located in
the purge section of the start string. It can be connected to the proving device (end switch,
flow switch etc.) of an auxiliary piece of equipment started by the unit's auxiliary relay. If the
delayed interlock is connected to a proving device that requires time to close (make), a time
delay (AUX START ON DLY) that holds the start sequence of the unit long enough for a
proving switch to make (close) can be programmed.
To use this option, you must disconnect the harness from the Delayed Interlock terminals
and connect the proving device in its place.
Should the proving switch not prove within the programmed time frame, the unit will shut
down. The Auxiliary Delay parameter can be programmed from 0 to 240 seconds (go to:
Main Menu → Advanced Setup → Ancillary Device →
2.11.13 Fault Relay (NC, COM, & NO)
The fault relay is a single pole double throw (SPDT) relay having a normally open and normally
closed set of relay contacts that are rated for 5 amps at 120 VAC and 5 amps at 30 VDC. The
relay energizes when any fault condition occurs and remains energized until the fault is cleared
and the CLEAR button is depressed.
2.11.14 Auxiliary Relay Contacts (NC, COM, & NO)
Each unit is equipped with a single pole double throw (SPDT) relay that is energized when there
is a demand for heat and de-energized after the demand for heat is satisfied. The relay is provided
for the control of auxiliary equipment, such as pumps and louvers, or can be used as a unit status
indictor (firing or not firing). Its contacts are rated for 120 VAC @ 5 amps. Refer to Figure 2-11
to locate the AUXILIARY RELAY terminals for wiring connections.
OMM-144_B • GF-217 •
5/25/2020
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Interlocks).
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