Table of Contents
Advertisement
Benchmark 2500DF-3000DF Installation, Operation & Maintenance Manual
constant setpoint temperature. That water is then circulated through a heat exchanger in a domestic hot
water storage tank.
Only the AERCO Control System (ACS) is necessary to configure this system if only a single valve is
used to switch from space heating to domestic hot water. However, the ACS Relay Panel is required in
combination with the ACS when there are up to two isolation valves, boiler interlocks, and/or a Domestic
Hot Water (DHW) pump in a Combination heating plant where AERCO boilers are being used for both
Building Heat and Domestic Hot Water heating.
The following two options are available for using a combination system; one that uses only the ACS, and
one that requires the optional ACS Relay Box:
•
OPTION 1 - This option is selected when the ACS controls a boiler plant containing up to eight
combination boilers that are Domestic Hot Water Priority (DHW PRIORITY) boilers, along with
building heat (BLDG HEAT) boilers, and one hydronic isolation valve in the main header between
the BLDG HEAT boilers and the DHW PRIORITY boilers.
•
OPTION 2 – When this option is selected, the ACS Relay Panel must be used in conjunction with
the ACS. For this option, the ACS controls a boiler plant containing up to eight combination boilers
that are divided up into Building Priority (BLDG PRIORITY) boilers and Domestic Hot Water Priority
(DHW PRIORITY) boilers, along with building heat (BLDG HEAT) boilers, and using two hydronic
isolation valves in the main header, one between the BLDG HEAT and BLDG PRIORITY boilers,
and the other between the BLDG PRIORITY and the DHW PRIORITY boilers.
In Option 2, when the space-heating load is such that when all the space-heating boilers are at the 100%
valve position, the ACS will then ask the ACS Relay Box for the domestic boilers to become space-
heating boilers. Provided the domestic hot water load is satisfied, the combo (hot water) boilers will then
become space-heating boilers. If the domestic hot water load is not satisfied, the combo boiler(s) remain
on the domestic hot water load. If the combo boilers switch over to space heating, but there is a call for
domestic hot water, the ACS Relay Box switches the combo units back to the domestic load. The ACS in
combination with the ACS Relay Box will ask the BLDG PRIORITY boilers to help with domestic hot water
heating if the DHW PRIORITY boilers are not able to satisfy the domestic hot water demand.
When the combo units are satisfying the domestic load, they are in the constant setpoint mode of
operation. When the combo units switch over to space heating, their mode of operation changes to follow
the ACS command. For more information concerning the operation of the ACS, consult the ACS
Operations Guide, GF-131. For more information on the ACS Relay Box, see section 2.14 in the same
manual.
5.7.1 Combination Control System Field Wiring
Wiring for this system is between the ACS, the ACS Relay Box, and the terminals in the I/O Box. Wire the
units using a shielded twisted pair of 18 to 22 AWG wire. When wiring multiple units, each unit's wiring
must conform to the above.
5.7.2 Combination Control System Setup and Startup
Setup for the Combination Mode requires entries to be made in the Configuration Menu for boiler mode,
remote signal type and setpoint. The setpoint is adjustable from 40°F to 190°F.
Enter the following settings in the Configuration Menu:
Menu Option
Boiler Mode
Remote Signal
Internal Setpt
Refer to section 3.3 for instructions on changing menu options.
Page 74 of 234
05/21/2014
CHAPTER 5 – MODE OF OPERATION
Setting
Combination
Network
40°F to 190°F
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Phone: 800-526-0288
OMM-0099_0A
GF-145
Advertisement
Table of Contents
