Weil-McLain Aqua Balance WMB-155 Manual page 77

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AquaBalance
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Setting the Air/Gas Ratio valve
There are two adjustments possible on the air/gas ratio valve,
the throttle setting at Maximum rate and the offset setting at
Minimum rate. If either setting is adjusted the combustion values
must be rechecked at both rates.
At Maximum Rate:
1. Adjust the boiler to Maximum rate in Figure 99, page 74,
Test Mode.
2. Wait 10 minutes to allow the boiler to stabilize.
3. Now adjust the Throttle setting (Figure 101 - screw A) until
the CO is at the correct SETTING LEVEL (see Figure 102),
2
below confirm that the CO/CO
wise to increase gas).
Figure 101 Throttle adjustment screw
(ONLY for use by a qualified technician, using
calibrated combustion test instruments).
Throttle adjustment
A
screw
Figure 102 Maximum rate combustion values –
measured values must be within the ranges
given below
Natural Gas/LP Acceptable Combustion Range
Maximum Rate after 10 minutes from cold
CO/(PPM)
Boiler Model
WMB-80 110
WMB-120 110
WMB-155
120
Part number 550-100-305/0118
M -
ALL OUNT GAS FIRED WATER BOILER
ratio is within limits (clock-
2
––
CO Max. Regulating screw
2
Test at Max Power 100%
Turn clockwise (open gas)
IRU ³0$; JDV ÀRZ´
Turn counter-clockwise
(close gas)
IRU ³0,1 JDV ÀRZ´
Rough start point
For LP Start up ONLY
Adjust gas valve
HIGH FIRE
screw on right with
Allen wrench turn
Counter-Clock wise
1-1/8 turns.
Final Combustion values
MUST BE checked with
Combustion Analyzer.
CO NG % CO LP %
2 2
9.0 – 9.5 10.2 – 10.7
9.0 – 9.5 10.2 – 10.7
9.0 – 9.5 10.2 – 10.7
—
Boiler Manual
(continued)
Using a combustion analyzer check the CO
values at low and high fire. It should be within
values from the table in Figure 102. The differ-
ence of CO
NEVER be below 0.2% or above 1%.
DO NOT
unless by a qualified technician, and with the
use of calibrated combustion test instruments.
Adjust the throttle screw only as needed to meet
the combustion values given in Figures 102 and
105, page 78.
Adjust in steps of no more than 1/8 of a turn and
wait 1 minute after each adjustment to allow the
setting to stabilize. Turning the screw too far will
cause the adjustment to reverse behavior.
4. In the event that the CO
CO/CO ratio cannot be obtained please contact your
2
Weil-McLain Technical Support for details.
5. Should you require any assistance during the set up pro-
cedure contact your Weil-McLain Technical Support if
the problem cannot be addressed with the information
provided in this manual.
6. Remove T-40 cap, see Figure 103, below, for Offset screw
adjustment.
Figure 103
Remove T-40 cover cap with supplied Torx
wrench for adjustment
from high fire to low fire should
2
attempt to adjust the throttle screw
setting level with an acceptable
2
2
77