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Benchmark 750-3000 Boiler Installation & Startup Manual
SECTION 2 – INSTALLATION
See Figures 2-13 and 2-14 for wiring details.
The Benchmark pump relay (SPDT) contact is rated for:
•
10 A Resistive @ 277 VAC/28 VDC
•
1/3 HP N/O @ 120/240 VAC
•
1/6 HP N/C @ 120/240 VAC
•
480 VAC Pilot Duty @ 240-277 VAC Pilot Duty
Figure 2-13: Schematic – System Pump Start using Boiler Pump Relay
If pump/valve load exceeds the above contact ratings, use a separate contact relay, as shown in
Figure 2-14.
Figure 2-14: Schematic – System Pump Start using a Separate Contact Relay
2.15 SEQUENCING ISOLATION VALVE INSTALLATION
All Benchmark units are pre-wired with a connection for an optional motorized external
sequencing isolation valve (P/N 92084-TAB). This valve is an integral component of the
AERCO's on-board Boiler Sequencing Technology (BST) solution. BST allows sites with
multiple boilers to have one boiler, acting as a "Manager" to manage the other boilers at the site,
designed as "Clients" in such a way that the efficiency of the entire boiler array is maximized.
When operated with the BST system, the Manager controls its own isolation valve and sends
signals to the Client units to open or close their isolation valves. After the boiler load is satisfied,
the isolation valve opens for a programmed interval (default = 1 minute) before closing. When
the system load is satisfied, the BST system will open the isolation valves for all of the boilers.
The implementation of BST, and the installation and use of this valve is optional. However,
when BST is implemented, use of this valve is strongly recommended.
Installation consists of installing the sequencing isolation valve in the hot water outlet pipe, and
then connecting it to the pre-wired connector on the shell harness, as described below.
OMM-0121_D • GF-205 • 5/9/2019
(Orange) –
N/O
Pump Relay Terminals
Heating Pump
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
(Orange) – N/O
(Yellow) - COM
Pump Relay Terminals
Heating Pump
Contact Relay
(Supplied by Others)
N
POWER PUMP(S) FROM
INDEPENDENT FUSED
CIRCUITS
H
Page 42 of 122
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