Troubleshooting - Weil-McLain EG 6 Series Manual

Universal Control Systems

Troubleshooting

Burner access panel must be in posi-
tion during boiler operation to prevent
momentary flame rollout on ignition of
main flame. Severe personal injury or
substantial property damage will result.
Never jumper (bypass) any device ex-
cept for momentary testing as outlined
in Troubleshooting Charts. Substantial
property damage and/or severe personal
injury could occur.
Label all wires prior to disconnection
when servicing controls. Wiring errors can
cause improper and dangerous operation.
Verify proper operation after servicing. See
vent damper manufacturer's instructions
packed with vent damper for additional
information. Failure to comply could
result in severe personal injury, death or
substantial property damage.
Before troubleshooting
1. Have a voltmeter that can check 120VAC, 24VAC,
and a continuity tester.
2. Check for 120VAC (minimum 102 to maximum
132) to boiler.
3. Make sure thermostat is calling for heat and contacts
(including appropriate zone controls) are closed.
Check for 24VAC between thermostat wire nuts and
ground.
Supply temperature/LWCO sensor
1. The boiler temperature/LWCO sensor is a
resistance-type device.
2. The Table 1, shows the correct value for the sensor
at various temperatures.
3. Use the resistance values at 32°F, 60°F, 70°F and
212°F to measure the sensor resistance at known
temperatures (ice point, room temperature and
sea level boiling point). For ice point and boiling
point, insert the sensor in water at that tempera-
ture. Use an ohmmeter to read resistance value
between thermistor # and thermistor common.
(See Figure 13 for pin locations).
Figure 10
Supply temperature/LWCO sensor
Part Number 550-142-304/1220
Table 1
Supply temperature sensor resistance values
Sensor resistance values
Sensor ohms
Temp
(°F)
Min
32
34265
40 27834
50 21630
60 16944
70
13372
80
10629
90 8504
100 6847
110 5545
In event of vent damper failure:
If troubleshooting chart recommends replacing actuator and actuator is
not immediately available, damper blade can be fixed in an open position
Manually turning blade can cause actuator
to allow boiler operation.
damage
. Follow these instructions only in case of no heat or damper
actuator malfunction.
1. Move damper service switch to
for heat to boiler. Damper blade should then rotate to open position
and boiler will fire.
2. If step 1 does not open damper, manually rotate damper blade to open
position using wrench or pliers on flat shaft between damper and actua-
tor. Boiler will fire. Verify that damper service switch is in Hold Damper
Open position (Figure 11, page 28).
3. Do not leave vent damper permanently in this position.
tor immediately. If vent damper is left in open position, boiler will not
operate at published efficiencies.
If troubleshooting chart recommends replacing actuator and actuator is
not immediately available, damper blade can be fixed in an open position
to allow boiler operation. Follow these instructions only in case of no heat
or damper actuator malfunction. See Figure 11, page 28.
1. Turn off power to boiler.
Failure to turn off power to boiler can result in severe personal
injury, death or substantial property damage.
2. Refer to vent damper manufacturer's instructions for procedure to fix
vent damper in open position.
3. Turn on power to boiler.
Sensor ohms
Temp
(°F)
Max Min
120
37871 4517
30764 130 3698
23907 140 3043
18727 150 2517
160
14780 2091
170
11747 1744
9399 180 1461
7568 190 1229
6129 200 1038
Hold Damper Open position. Apply call
Max
4992
4088
3364
2782
2311
1928
1615
1359
1147
Replace actua-
27