Specifications

Part number 550-142-120/0113
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WM97+ gas-fired water boiler — Boiler Manual
Annual startup (continued)
Check ignition wiring
1. Check ignition cable electrical resistance. A good cable will
have resistance between 950 and 1050 ohms. Replace if not
acceptable.
2. Inspect boiler ground wire from heat exchanger access cover
to ground terminal screw.
3. Verify all wiring is in good condition and securely attached.
4. Check ground continuity of wiring using continuity meter.
5. Replace ground wires if results are not satisfactory.
Check all boiler wiring
1. Inspect all boiler wiring, making sure wires are in good condi-
tion and securely attached.
2. Verify that all connectors are securely inserted.
Check control settings
1. Use the WM97+ control display to navigate through all set-
tings. Adjust settings if necessary.
2. Check settings of external limit controls (if any) and adjust
if necessary. Adjust as needed to accommodate the system
design.
Perform startup and checks
1. Start boiler and perform checks and tests specified in this
manual.
2. Verify cold fill pressure is correct and that operating pressure
does not go too high. Adjust water pressure and expansion
tank charge pressure as necessary.
3. Complete the check-out procedure on page 94.
CWH installations only — verify
operation per CWH manual
1. If a Companion Water Heater (CWH) is installed, follow
instructions in the CWH manual to set and verify operation
of the water heater.
Check low water cutoff service light
1. If the low water cutoff amber LED is on, the control requires
service. Follow the low water cutoff manufacturer’s instruc-
tions (shipped with the boiler in the literature envelope).
Check burner flame
The boiler contains ceramic fiber materials. Use
care when handling these materials per instructions
on page 96 of this manual. Failure to comply could
result in severe personal injury.
1. Inspect flame through observation window using the pro-
cedure on page 90.
2. If flame is unsatisfactory at either high fire or low fire, check
combustion values. If combustion is properly adjusted, turn
off boiler and allow boiler to cool down. Then remove burner
and clean it thoroughly using a vacuum cleaner or compressed
air. Do not use compressed air to clean burner if performed
inside a building.
3. To access the burner, remove the heat exchanger cover plate
following the procedure beginning on page 112.
4. If replacing the burner, ensure the burner gasket is in good
condition and correctly positioned. Follow all instructions
on page 112 to reinstall all components.
5. Restart the boiler.
6. Inspect the flame at high and low fire. If flame is still not ac-
ceptable, check combustion values. If combustion is properly
adjusted, obtain a replacement burner from Weil-McLain.
Check flame signal
1. Navigate to Diagnostics/Inputs on the WM97+ control
display (see Figure 84, page 74 for navigation instructions
and Figure 93, page 83 for the complete Diagnostics menus).
2. The flame signal value must be at least 75 for a WM97+70
or 110, or at least 160 for the WM97+155. If the flame signal
drops below this level, the WM97+ control will attempt to
correct by increasing the boiler firing rate to increase flame
signal.
Figure 105
Flame signal shutdown values
Model
WM97+
Shutdown
flame signal
Model
WM97+
Shutdown
flame signal
70 50 155 150
70 HA 50 155HA 150
110 50
NOTE: “HA” means high altitude,
5500 feet or more above seal level.
110 HA 50
3. A low flame signal may indicate a fouled ignitor or damaged
ignitor insulation.
a. See “Inspect ignition electrode,” page 98 to remove and
inspect the ignitor.
b. If required, clean the igniter as instructed.
c. If cleaning the ignitor does not improve, ground wiring is
in good condition, and ground continuity is satisfactory,
replace the ignitor.
4. If flame signal still remains low:
a. Inspect the vent and air piping.
b. Check combustion values.
c. Then inspect the heat exchanger, following the procedures
given in this manual for removal and reinstallation of the
head exchanger cover plate and other boiler components
(see page 112).
d. Clean the exchanger as described in this manual if nec-
essary.