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AERCO Control System (ACS)
CHAPTER 2
: ACS Installation
Page 40 of 139
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, New York 10913
11/22/2017
GF-131
Phone: 800-526-0288
OMM-0081_0F
RELAY PANEL OPERATION
2.17
Figure 2-15: ACS Relay Panel Front Panel
The board operates basically as follows:
Relay Panel Operation
a) In the normal idle state, all the inputs, except one of the Valve End Switch In inputs, would be
open. As a result, the Aquastat Out would be open and the Valve End Switch Out would be
closed. All the relays except the Interlocks Relay will be in their unpowered state – DHW Pump
off, Valve 1 closed(N.C. powered), and Valve 2 open (N.C. powered). Since the Valve End
Switch Output would be activated, all the Interlocks relays will be activated and all its contacts
closed thereby enabling the Building Priority boilers to run if needed.
NOTE
If no Valve 2 (Sys Relay) is used, the Interlocks Relay connection will
not need to be used.
b) When the tank calls for heat and the Aquastat Input closes, the DHW Pump relay will activate.
The ACS will activate Valve 1 to close if it is not already closed. Once closed the ACS will
allow the DHW Priority boilers to run to provide heat to the tank.
If all the DHW Priority boilers are running at 100% for more than 2 minutes, the ACS will open
Valve 1 and close Valve 2 and activate the Building Priority boilers to help with DHW heating.
When the Aquastat Input opens, the DHW Pump will turn off after some time delay (currently
60 seconds). The DHW Priority boilers will also shut down and Valve 1 will close and Valve 2
open.
c) Generally if any of the two valves is fully open and its Valve End Switch Input closes, the
Interlock relays will activate to allow the Building Priority boilers to run. When the Valve End
Switch Input opens, the Interlock relays will de-activate.
d) The Valve 1 Relay output is labeled such that the Normally Closed (N.C.) contact is Valve 1
Close and the Normally Open (N.O.) contact is Valve 1 Open. The Valve 2 Relay output is
labeled such that the Normally Closed (N.C.) contact is Valve 2 Open and the Normally Open
(N.O.) contact is Valve 2 Close. It is important to make these connections correctly. In this
way, the unpowered state of the relay panel will keep the valves in the default state with Valve
1 closed and Valve 2 open.
Clear Plastic
Cover
Wiring Compartment Cover
Front Panel