Install Instructions

Startup — fi nal checks (continued)
Th rottle screw adjustment
EVG 155 ONLY
DO NOT attempt to adjust the throttle screw unless 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 when specifi ed
elsewhere in this manual or when 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: difficulty igniting, poor flame stability at low fire,
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 85 for location of the
EVG 155 throttle screw.
Figure 85 EVG 155 Throttle screw (ONLY for use by a qualifi ed
technician, using calibrated combustion test
instruments)
❏ Chec k Heat exchanger and vent seals
1. Operate the boiler on HIGH fi re.
2. Using an inspection mirror, move the mirror around
all heat exchanger joints and vent pipe connections
at the top of the boiler and at the connection to the
condensate dish.
3. A leak would appear as vapor on the surface of the
mirror.
4. If there is any indication of a leak at any joint,
immediately shut down the boiler.
a. If possible, tighten the retaining screws or nuts
(without over-tightening).
b. If this does not correct the problem, disassemble
the components where the leak appeared. Use the
procedures given in the Maintenance section of
this manual.
c. When disassembling components, inspect gaskets
to see if there is damage. Replace any damaged
gasket.
d. Contact your Weil-McLain representative if the
problem cannot be addressed with the information
provided in this manual.
5. Condensate dish joint
a. If the inspection mirror check shows a leak at the
condensate dish-to-heat exchanger joint, contact
your Weil-McLain representative for instructions
to correct the problem.
b. If the mirror test does not reveal a leak at the
condensate dish joint, but there are signs of
weepage or other indications that there might be
leakage, follow the procedure for checking the heat
exchanger-to-condensate dish seal.
Figure 86 Acceptable combustion values —
measured values must be within the
ranges given below
Gas inlet
pressure
test port
Throttle adjustment screw
Adjust the throttle screw in small movements.
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.
a. If the CO
2
is HIGH, turn the throttle screw CLOCKWISE to lower
the input. Allow the boiler to stabilize and take another reading.
Continue until the desired CO
2
value is achieved.
b. If the CO
2
is LOW, turn the throttle screw COUNTERCLOCKWISE
to increase the input. Allow the boiler to stabilize and take another
reading. Continue until the desired CO
2
value is achieved.
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.
Part number 550-100-191/0917
98
®
gas-fired water boiler — 70/110/155 Boiler Manual
Boiler
model
EVG
Fuel
High fi re Low fi re
%
CO
2
CO
ppm
%
CO
2
CO
ppm
70
NG 9.25 +/ – 1.0 < 150 9.25 +/ – 1.0 < 50
LP 10.0 +/
– 0.5 < 150 10.0 +/ – 0.5 < 50
110
NG 9.5 +/ – 0.5 < 150 9.0 +/ – 0.5 < 50
LP 10.5 +/
– 0.5 < 150 10.0 +/ – 0.5 < 50
155
NG 9.25 +/ – 1.0 < 150 8.75 +/ – 1.0 < 50
LP 10.25 +/
– 0.5 < 150 9.75 +/ – 0.5 < 50
• Values above are with the boiler jacket door
removed. Values will increase about 0.2% once the jacket
door is reinstalled.
•
REINSTALL the boiler jacket door after completing
service.
• Values above are for altitudes up to 5,500 feet. For higher
altitudes, CO
2
may be slightly lower and CO slightly higher.
•
Low fi re CO
2
should be equal to or less than High fi re CO
2
.