Weil-McLain AHE Series Manual page 37

AHE Series 4 Direct Vent Wall-Mounted Boilers — Boiler Manual
12d
Troubleshooting — charts
Electrical shock hazard — Wherever you see
instructions could result in severe personl injury, death or substantial property damage.
• TURN OFF POWER
• Remove CONTROL CIRCUIT plug from control module receptacle ( Figure 29, page 34, Item 5 ).
• Remove a wire from one of the limit control spade connectors.
• Connect an ohmmeter across the left and right pins on the center row of the limit circuit harness.
• Replace control wiring harness.
• Retest.
• Replace the 47K resistor.
• Retest.
• Close the external manual gas valve.
• Remove one wire from the limit control
space connector.
• Set a thermostat to call for heat. Then
turn on power to the boiler at the 120
VAC service switch.
• The boiler system circulator should come
on and the control module should try to
cycle the boiler.
• Allow the boiler circulator to run to cool
off boiler and system water.
• After the boiler and system water have
cooled, turn off power at the 120 VAC
service switch and open the external
manual gas valve.
Part number 550-141-887/0800
CHART 3 — LIMIT & POWER lights flashing
to boiler at 120 VAC service switch.
Does the ohmmeter indicate a shorted wire harness (zero ohms)?
Yes
continued
TURN OFF POWER , follow the instructions. Failure to follow
• Reconnect CONTROL CIRCUIT plug to control module.
• Replace with 47K resistor (Figure 29, page 34, Item 6).
• Connector an ohmmeter across the plug pins to check
the sensor resistance.
Does the ohmmeter indicate a shorted sensor (zero ohms)?
Yes
Yes
• Set limit control knob to its minimum setting. Replace
wire to limit control spade connector.
• Set a thermostat to call for heat.
• Turn on power at 120 VAC service switch.
• Control module should cycle boiler on and begin heating.
• The limit control should shut off the gas valve when the
temperature at the boiler pressure/temperature gauge
has reached no more than about 20 ˚F higher than the
limit switch setting.
Does limit control shut off gas correctly?
Yes
• Replace control
module.
• Retest.
No
No
Is boiler hot?
No
No
• Replace limit control
and block tempera-
ture switch.
• Retest.
37