Section 9: Aertrim Operation; Aertrim Introduction - Watts AERCO Benchmark BMK5000 Operation And Service Manual

Benchmark Platinum-Edge [ii]: Operation-Service Manual
SECTION 9 – AERTRIM OPERATION

SECTION 9: AERTRIM OPERATION

9.1 AERTRIM INTRODUCTION

Advanced combustion control systems need to maintain precise air/fuel ratios to maximize
efficiency. Gas and oil-fired boilers often deviate from the ideal air-fuel ratio due to
environmental variations such as humidity, atmospheric pressure, filter dust loading, delivered
gas energy content and other factors. If the boiler is operating with fixed blower/damper
positions, the air/fuel ratio will normally vary within an acceptable level but will not be fully
optimized for efficiency and reliability.
The AERtrim system is designed to measure and maintain an ideal air-fuel ratio in Benchmark
boilers, thus maximizing efficiency and reliability while minimizing emissions. It does this by first
measuring post combustion oxygen percentages inside the combustion chamber. This data is
fed through the Electronic Control Unit (ECU) which is connected to the Edge Controller inside
the boiler. If the oxygen readings are outside of preset or user defined values, the blower
voltage is changed in small increments until the reading falls within the ideal range.
A simplified representation of the system is shown in Figure 9-1.
Oxygen Input
CanBus
Sensor ECU
CanBus
WARNING:
AERtrim and combustion calibration can both alter the voltage sent to the blower and can thus
interfere with each other. If a change is made to any calibration point during combustion
calibration, you must make a corresponding change to the same calibration point in AERtrim.
If you fail to make the change in AERtrim, AERtrim may ignore the combustion calibration
value and adjust the O
OMM-0137_J •
12/20/2022
O Sensor
2
Combustion Chamber
Edge Controller
Figure 9-1: Simplified AERtrim Diagram
to the AERtrim value instead.
2
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Blower
Burner
Voltage Output
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