Table 1: Course adjustment settings—Throttle and offset
adjustments to be made prior to first ignition, by
size.
Boiler
Model
Throttle Turns
(Counterclockwise
from Bottom-out
Position)
Offset Turns
(Counterclockwise
from Factory NG
Position)
220 LP
3/4
1/4
299 LP
1-3/8
1/4
399 LP
1-5/8
1/4
Before firing, verify that the “Max Rate” for the input
(priority) used to fire the boiler is set between 96% and
100%. Also verify that the ‘Min Rate” is set to 10% or the
minimum rate allowed (if above 2000 ft. elevation).
Adjust control settings if not at proper rate. Verify that
boiler is operating at the expected firing rate at both
high- and low-fire during combustion analysis. Refer to
Table 2 for proper low-fire rate based on altitude settings.
During combustion analysis, ensure boiler is
operating at the expected firing rate. Failure
to operate boiler at proper rate during
combustion testing and adjustment could
result in incorrect combustion settings.
Improper gas valve settings can cause
severe personal injury, death or property
damage.
Table 2: Low-fire blower speeds—Minimum blower
speed settings according to altitude settings.
Altitude
Setting (ft.)
Lowest Rate for Altitude
220
299
399
0-2000
10%
10%
10%
2500
11%
11%
12%
3000
12%
11%
12%
3500
12%
11%
12%
4000
12%
12%
13%
4500
13%
12%
13%
5000
13%
12%
13%
5500
13%
13%
14%
6000
14%
13%
14%
6500
14%
13%
14%
7000
14%
14%
15%
7500
15%
14%
15%
8000
15%
14%
16%
8500
15%
14%
16%
9000
16%
15%
16%
9500
16%
15%
17%
10000
17%
15%
17%
10500
17%
16%
17%
11000
17%
16%
18%
Review the procedure and control sequence for the
operation of the Manual Test Mode in the section of the
boiler manual “Manual Test Mode for Single and Multiple
Boilers”. The procedure differs between boilers set as a
single or multiple-boiler unit.
Do NOT allow the boiler to modulate freely until the
combustion analysis and adjustment is complete. Fire
the boiler and force it to High Fire in Manual Test Mode.
Adjust the high fire combustion first, using the throttle
adjustment screw, to the specification in the boiler
manual, reproduced in Table 3. Then, force the boiler to
low fire and adjust the offset regulating screw to the
specification in the boiler manual, reproduced in Table 3.
Follow the full startup instructions found in the Evergreen
Boiler Manual.
Table 3: Acceptable combustion values—measured
values must be within the ranges given below.
Boiler
Model
High Fire
Low Fire
% CO2
CO
ppm
% CO2
CO ppm
220 LP 10.75 ±0.50
< 120
10.25 ±0.50
< 50
299 LP 10.75 ±0.50
< 120
10.25 ±0.50
< 50
399 LP 10.75 ±0.50
< 120
10.25 ±0.50
< 50
To clarify, both the high fire and low fire gas adjustment
MUST be made with a properly working, calibrated
combustion analyzer according to the instructions in the
boiler manual to ensure safe, reliable operation.
The coarse adjustment prescribed by this bulletin should
result in combustion settings that allow for ignition and
are a starting point for further adjustment. If, after
following the procedure above, the boiler will not ignite
or, during combustion analysis, the analyzer reads less
than 1.0% O
2
, contact Weil-McLain Technical Services for
assistance.
