AERCO Modulex High Pressure Manual - Manual (Page 36)

INSTALLATION, OPERATION & MAINTENANCE
6-2
6.3 IGNITION SEQUENCE
The ignition sequence is described below and shown in the following diagram (Figure 6-1). The Ignition
Burner Management Module (BMM) is powered on and, after 5 seconds the fan starts at minimum
speed. The fan remains running, actuating the air pressure switch and pre-purging the combustion
chamber for 10 seconds. Actuating the air pressure switch toggles it from normally open (NO) to
normally closed (NC). This energizes the ignition transformer 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
conditions occurs and the display on the System Manager will show an error message.
Figure 6-1.
6.4 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 Modulex E8 Controller Manual GF-115-C for additional information on operating
modes, set-up and programming.
6.4.1 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.