Install Instructions

Startup — final checks (continued)
If combustion at either high or
low fire is outside the range given
in Figure 87, page 81, follow the
procedure given on page 80 or
page 81 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 ap-
pliances.
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 rat-
ing on boiler rating label.
8. Use the ECO control display to navigate to Manual
test mode (see Figure 80, page 72) and force the
firing rate to LOW (low fire).
9. Look at the flame through the flame inspection
window. The low fire flame should be stable and
evenly distributed over burner surface with a uni-
form orange color.
10. Repeat the combustion test as instructed in the
previous steps.
11. Use the ECO control display to navigate to Manual
test mode (see Figure 80, page 72) and force the
firing 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 flue pipe, then insert the probe into the rubber
grommet.
You must reinstall the flue gas tempera-
ture sensor to prevent flue gas spillage
into the boiler enclosure. Failure to com-
ply could result in severe personal injury,
death or substantial property damage.
Throttle screw adjustment
%#/OR/.,9
$/./4 attempt to adjust the throttle screw unless by a quali-
fied 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 87
1. Throttle screw adjustment is
ONLYNECESSARYif specified elsewhere in
this manual or if combustion tests indicate the need, as explained under
“❏#HECKmAMECOMBUSTIONWITHINSTRUMENTS,” page 78.
2. Boiler behavior that might indicate a need to check combustion values
at high fire (as per page 78) to verify boiler is in adjustment include:
difficulty igniting, poor flame stability at low fire, combustion noise
or high carbon monoxide values.
3. Combustion readings must be taken at both high fire and low fire. DO
NOT attempt an adjustment of the throttle screw at low fire. Just check
the combustion values.
4. See Figure 86 for location of the
%#/OR throttle screw.
&IGURE
%#/ Throttle screw (ONLY for use by a
qualified technician, using calibrated combustion test
instruments)
4HROTTLEADJUSTMENTSCREW
'ASINLETPRESSURETESTPORT
Adjust the throttle screw in small movements. Turning the
screw too far will cause the adjustment to reverse behavior.
5. See page 69 and Figure 77, page 70. Make sure the Max firing rate is set
to the maximum given in the table. If not, adjust as necessary. Then navi-
gate to DIAGNOSTICS — Manual test mode (see Figure 80, page 72)
and force the firing rate to HIGH (high fire). 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.
6. Lock the boiler into low fire. Check the combustion readings. If results
are acceptable at low fire, verify high fire readings again. Restore firing
rate to AUTO. DO NOT adjust throttle on low fire.
7. Consult your local Weil-McLain representative if acceptable results
cannot be obtained for both high and low fire.
Part number 550-142-122/0513
80
TM
GAS-FIRED WATER BOILER — Boiler Manual