AERCO Control System (ACS) - Manual (Page 56)

MC2: 04/23/13 Page 56 of 144
GF-131
AERCO Control System (ACS)
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, New York 10913 • Phone: 800-526-0288
Installation, Operation, and Maintenance Manual
OMM-0081_0D
maximum temperature difference allowed between the Header temperature and the Return
temperature. If we exceed this value by 18°, the ACS will shut down the boiler plant. When the
temperature difference gets below the PLANT DT LIMIT, the boiler plant will be activated again.
The Return TC must be installed for this function to operate.
3.9.15 BOILER DELAY
The BOILER DELAY is the minimum wait time after firing one boiler before firing the next one.
It can be set from 10 seconds to 999 seconds. The default is 30 seconds.
3.9.16 DHW OPTION (Domestic Hot Water Option)
There are four DHW selections to choose from: NO OPTION, OPTION 1, OPTION 2, and
OPTION 3. Option 1 and 2 do NOT apply to Modulex boilers.
•
NO OPTION - The default, NO OPTION, disable all options and allows the ACS to function
strictly for building heating.
• OPTION 1 - This option is selected when the ACS is to control a boiler plant containing up to
8 combination boilers that are Domestic Hot Water Priority (DHW PRIORITY) boilers, along
with building heat (BLDG HEAT) boilers, and using one hydronic isolation valve in the main
header between the BLDG HEAT boilers and the DHW PRIORITY boilers. When this option
is selected, the AUX Relay will act as the DHW valve open contact and the SYS Relay will
act as the DHW valve close contact (unless the SYS relay is programmed otherwise by the
SYS relay option setting), the interlock 2 will act as the Valve End Switch input, and Setback
will be used as the Aquastat input. When this option is selected, there are three other
settings that will be displayed - NUMBER DHW BLRS, DHW SIGNAL, and SYS RELAY
OPTION. These will be defined later.
• OPTION 2 - This option is selected when the ACS is to control a boiler plant containing up to
8 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. When this option is selected, the ACS Relay Panel must
be used in conjunction with the ACS. See sections 2.14 to 2.18 for wiring and operation.
When this option is selected, there are three other settings that will be displayed - NUMBER
DHW BLRS, DHW SIGNAL, and NUM DHW PRIORITY. These will be defined later.
• OPTION 3 - This option is selected when the ACS is to boost the setpoint temperature of the
whole boiler plant when the domestic system is calling for heat. Boost is activated by closing
Interlock 2 and deactivated by opening the Interlock. When this option is selected, three
other settings are displayed - BOOST TEMP, RET TMP BST DIS, and BOOST MAX TIMER.
These will be defined later.
See section 2.15 for wiring any of these options. The extra settings are defined below:
3.9.17 NUMBER DHW BLRS (Number of Domestic Hot Water Boilers)
Selects the total number of boilers being used to help supply domestic hot water. If these are
C-More controls, their Boiler Mode would be programmed as Combination. This selection
applies to OPTION 1 and OPTION 2. For OPTION 1 they would all be DHW PRIORITY boilers.
For OPTION 2 they would be the total of DHW PRIORITY boilers and BLDG PRIORITY boilers.
NUM DHW PRIORITY differentiates between the two types.