Combustion Fuel to Air Ratio

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Air Density Trim Control
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Webster Engineering, a leader in burner
manufacturing and combustion control, now offers
a combustion air temperature trim system that
should give you a 2-3 savings in your fuel bill.
With out the cost and complexity of a
conventional O2 trim system.
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Combustion Fuel to Air RatioBurner Set-up
Air
This represents a normal set-up _at_ 80 degrees -
trying to make the burner as efficient as
possible.
A burner is set up to run efficiently by mixing
the proper mass of fuel and the proper mass of
air.
Efficient mass of Gas to mass of Air White circle
Volume Yellow circle Mass
Efficient ratio at 80o F Results in 3 O2
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Combustion Fuel to Air Ratio
Combustion Air Temperature Changes
The Temp A Trim Solution
Burner Fans Produce Constant Volume of Air
Volume of Air _at_ 80o
Unburned fuel and high CO
Efficient operation
Volume increases with higher temperature, but
mass remains the same
Ratio at 120o F
Results in 1.5 O2
Results in 3.0 O2
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Combustion Fuel to Air Ratio
The Temp A Trim Solution
Burner Fans Produce Constant Volume of Air
Volume of Air _at_ 80o
Efficient operation
Inefficient operation
Volume decreases with lower temperature, but mass
remains the same
Ratio at 40o F
Results in 4.5 O2
Results in 3.0 O2
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Thats what the does. It
measures the combustion air temperature and
adjusts the fan motor speed to maintain the
correct mass of air. Thus allowing you to set
and hold an optimum excess air or O2 level.
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Typical Combustion Air Temperature Variations
High Temp. 121 F.
Low Temp. 58 F.
Site located in Winfield, Kansas Dry Cleaners
Date 8/2/07
Date 10/23/07
Burner saw a 63 F temperature swing prior to the
cold of winter. TEMP A TRIM maintained a
consistent O2 reading.
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System Layout
TAT Circuit Board
Flame Safeguard (existing)
Motor / Blower Wheel (existing)
VFD Control
Sensor
Air Flow
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System Layout Retro-Fit Application Components
TAT circuit board / slave relay in separate
enclosure
VFD display
Variable frequency drive
Sensor (Thermistor)
Conduit and wiring by field personnel.
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System Layout Retro-Fit Application
Flame Safeguard
TAT circuit board / slave relay in separate
enclosure
VFD display
Original Burner control panel
Sensor (thermistor) mounted at Burner air inlet
Variable frequency drive
TAT Board, sensor and VFD field wired
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System Layout New Application Burner Mount Panel
TAT circuit board / slave relay in Burner panel
Flame Safeguard
VFD display
Variable frequency drive, mounted on outside of
panel
Burner
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System Layout New Application Burner Mount Panel
Burner panel
Burner
Air Louver Box
Sensor (Thermistor)
Air flow
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System Layout New Application Remote Mount Panel
TAT circuit board / slave relay in own junction
box
Remote Control Panel
Air Louver Box
Sensor (Thermistor)
Variable frequency drive, mounted on outside of
panel (mounted in field)
VFD display
TAT circuit board and sensor wiring by Webster
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System Layout New Application Remote Mount Panel
TAT circuit board / slave relay in own junction
box
TAT circuit board and sensor wiring by Webster
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TEMP A TRIM Circuit Board
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Thermistor Location
Cold Ambient Air
Warmer Air
Combustion Air Flow Cooler Air
Sensor
Boiler room wall louvers
Warmer Air
The TEMP A TRIM Sensor should be located within
the path between the boiler room louvers and the
burner louver box.
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Patent Pending
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LogTag Temperature Recorder
Sample Graph from LogTag Readings
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Payback Analysis
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Air Density Trim Control
Thank you for your time
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