Owner's manual

GF-123 Benchmark 2.0LN Low NOx Boiler Chapter 3

OMM-0046_0E Installation, Operation and Maintenance Manual Operation

PR1 08/20/12 AERCO International Inc.● 100 Oritani Dr. ● Blauvelt, NY 10913. ● Ph: 800-526-0288 Page 43 of 170

3.9 START SEQUENCE

When the Control Box ON/OFF switch is set to the ON position, it checks all pre-purge safety

switches to ensure they are closed. These switches include:

• Safety Shut-Off Valve Proof of Closure (POC) switch

• Low Water Level switch

• High Water Temperature switch

• High Gas Pressure switch

• Low Gas Pressure switch

• Blower Proof switch

• Blocked Inlet switch

If all of the above switches are closed, the READY light above the ON/OFF switch will light and

the unit will be in the Standby mode.

When there is a demand for heat, the following events will occur:

NOTE

If any of the Pre-Purge safety device switches are open, the appropriate fault message will be

displayed. Also, the appropriate fault messages will be displayed throughout the start

sequence, if the required conditions are not observed.

1. The DEMAND LED status indicator will light.

2. The unit checks to ensure that the Proof of Closure (POC) switch in the downstream Safety

Shut-Off Valve (SSOV) is closed. See Figure 3-3 for SSOV location.

3. With all required safety device switches closed, a purge cycle will be initiated and the

following events will occur:

(a) The Blower relay energizes and turns on blower.

(b) The Air/Fuel Valve rotates to the full-open purge position and closes purge position

switch. The dial on the Air/Fuel Valve (Figure 3-4) will read 100 to indicate that it is full-

open (100%).