Weil-McLain Evergreen EVG 110, Manual

Page: 96 / 144

Adjustment” on page 96 or page 98 to set the throttle
screw position. See
WARNING
on page 96 upper left.
If combustion at either high or
low fi re is outside the range given
in Figure 86, page 98 , follow the
procedure given on page 96 or
page 98 for adjusting the throttle
screw on the venturi. If throttle
screw adjustment does not correct
the problem, then shut down the
boiler and contact your local Weil-
McLain representative. Throttle
screw adjustment must be done
only by a qualified technician,
using calibrated test instruments.
Failure to comply could result in
severe personal injury, death or
substantial property damage.
7. Measure natural gas input:
a. Operate boiler 10 minutes. Turn off other
appliances.
b. At natural gas meter, measure time (in seconds)
required to use one cubic foot of gas.
c. Calculate gas input:
3600 x 1000
= Btuh
number of seconds from step b
d. Btuh calculated should approximate input rating
on boiler rating label.
8. Use the control display to navigate to Manual test
mode (see Figure 76, page 85 ) and force the fi ring
rate to LOW (low fi re).
9. Look at the flame through the flame inspection
window. The low fi re fl ame should be stable and
evenly distributed over burner surface with a uniform
orange color.
10. Repeat the combustion test as instructed in the
previous steps.
11. Use the control display to navigate to Manual test
mode (see Figure 76, page 85 ) and force the fi ring
rate to AUTO (normal operation).
12. Reinstall the flue gas temperature sensor. When
replacing the sensor, remove the rubber grommet
from the probe. Insert the rubber grommet into
the fl ue pipe, then insert the probe into the rubber
grommet.
You must reinstall the fl ue gas temperature
sensor to prevent fl ue gas spillage into the
boiler enclosure. Failure to comply could
result in severe personal injury, death or
substantial property damage.
Throttle scr ew adjustment
EVG 70 ONLY
DO NOT attempt to adjust the throttle screw unless done
by a qualifi ed technician, and with the use of calibrated
combustion test instruments. Adjust the throttle screw only
as needed to meet the combustion values given in Figure 86 .
1. Throttle screw adjustment is only necessary if specifi ed elsewhere in
this manual or if combustion tests indicate the need, as explained under
“
❏
Check fl ame & combustion with instruments
,” page 94.
2. Boiler behavior that might indicate a need to check combustion values
at high fi re (as per page 94 ) to verify boiler is in adjustment include:
diffi culty igniting, poor fl ame stability at low fi re, combustion noise
or high carbon monoxide values.
3. Combustion readings must be taken at both high fi re and low fi re. DO
NOT attempt an adjustment of the throttle screw at low fi re. Just check
the combustion values.
4. See Figure 83 for location of the
EVG 70
throttle screw.
Figure 83 EVG 70 Throttle screw (ONLY for use by a qualifi ed
technician, using calibrated combustion test
instruments)
Throttle adjustment screw crew
Adjust the throttle screw in small movements. Turning the
screw too far will cause the adjustment to reverse behavior.
5. Make sure the Max fi ring rate is set to the maximum and confi rm the
RPM value during operation given in Figure 90, page 105 . If not, adjust
as necessary. Then navigate to DIAGNOSTICS — Manual test mode
(see Figure 76, page 85 ) and force the fi ring rate to HIGH (high fi re).
After the boiler has had time to stabilize, take a CO
2
reading. If result
is not acceptable, do the following:
a. Turn the throttle screw either direction very slightly. Allow the
boiler to stabilize and take another CO
2
reading. Note whether CO
2
increases or decreases.
b. Turn the screw slightly in the direction needed to increase or
decrease reading as needed. Allow the boiler to stabilize and take
another reading. Continue until CO
2
is acceptable.
c. Confi rm that the CO is within limits.
6. Lock the boiler into low fi re. Check the combustion readings. If results
are acceptable at low fi re, verify high fi re readings again. Restore fi ring
rate to AUTO. DO NOT adjust throttle on low fi re.
7. Consult your local Weil-McLain representative if acceptable results
cannot be obtained for both high and low fi re.
Gas inlet
pressure
test port
Gas inlet
pressure
test port
Part number 550-100-191/0917
96
®
g
as-fired water boiler —
70/110/155
Boiler Manual
Startup — fi nal checks
(continued)