MC2: 10/03/12 Page
34
of
90
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
•
Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 7: Boiler
Operation
transformer and permits the gas valve to be opened after 5 to 8 seconds allowing the AIR/GAS mixture
into combustion chamber through the check valve. If the burner does not light within the ignition time
frame, the burner is put in lockout position for 5 sec, after which it repeats the ignition sequence once
again. If no positive result is obtained, then a lockout condition occurs and the display on the System
Manager will show an error message.
NOTE
When power is applied, fans are already on to prevent back flow through
the air system.
7.4 Modes of Operation
The Modulex boiler is capable of operating in several control modes including, Indoor/Outdoor Reset, 0
to 10 Volt Remote Setpoint, and Constant Setpoint. The following subordinate paragraphs briefly
describe each of these modes.
NOTE
Refer to the Modulex E8 Controller Manual
GF-115C
for additional
information on operating modes, set-up, and programming of the E8
Controller.
7.4.1 Indoor/Outdoor Reset
In indoor/outdoor reset mode the Modulex boiler will adjust its set-point based on the outside air
temperature and the programmed heating curve. The heating curve can be customized by changing the
Slope parameter found in the User/ Heating Circuit 1 menu in the boilers controller.
The outside air sensor, supplied with the boiler, should be mounted on an outer North or Northeast wall
at a minimum height from floor of 8 feet, 2.5 inches (2.5 m) away from windows, doors and ventilation
grates. Never mount the outside air sensor in a sunny position. The sensor connections are at
connector #1, terminals 9 (F9) and 10 (GND) of controller.
7.4.2 0 To 10 Volt Remote Set-Point
The unit’s setpoint can be controlled using a 0 to 10 volt signal. The Modulex controls allow for full
scaling capabilities of voltage and set-point through use of the V-Curve in the Expert Menu of the
Controller. Input wiring for this mode will be to terminals 1 (F15) and 2 (GND) of the E8 Controller
connector number 3 (III). See
Sub-section 5.3
in E8 Controller Manual,
GF-115-C
.
7.4.3 Constant Set-Point
The constant set-point mode is used when a fixed header temperature is desired. Common uses for
this mode of operation include water source heat pump loops and indirect heat exchangers for potable
ho water systems or processes. No external connections are required for this mode of operation.
7.4.4 Boiler Operation for Troubleshooting (Manual Mode)
For service and test purposes, any single module, or all simultaneously, can be kept operating at full or
reduced load. In this way the CO
2
level can be checked and, if necessary, adjusted at full or reduced
load (for any single module or for all simultaneously). With this option, troubleshooting failures on each
module is simplified.
7.5 Modulex Boiler Initial Startup
Prior to initial start-up of the complete Modulex Boiler, check the following items:
•
Ensure that all Installation procedures have been completed as presented in
Section 3
of this
document (
GF-115-H
), including references to documents
GF-115-G
(Gas),
GF-115-P-H
(Piping),
GF-115-V
(Venting), and
GF-115-E
(Electrical).
•
Ensure that all operating controls, menu settings, and limits have been properly set in accordance
with
Section 3
of the Modulex E8 Controller Operation & Wiring Guide
GF-115-C
(Controls).
