Weil-McLain 550-141-396/0801 Troubleshooting, Symptom-No heat, Symptom-Boiler does not shut down

PER Series 3 Electric-Hydronic Boilers Installation Instructions

Troubleshooting

This boiler contains fiberglass materials. Use care when handling these materials per instructions on page 11 of this manual. Failure to comply could result in severe personal injury.

Symptom—No heat

1.Check fuses. Power for the control circuit is supplied through the fuses for the heating element, and the circulator.

2.If fuses are good, jumper the thermostat terminal. If boiler starts, check the thermostat and associated wiring.

3.If thermostat and wiring are good, check the limit control.

a.Jumper the “R” and “B” terminals on the “low” side of the control. If the boiler starts, replace the limit control.

b.If the boiler does not start in step “a”, momentarily jumper the “R” and “B” terminals on the “high” side of the control. If the boiler starts, replace the limit control.

4.If the limit control is good, check the transformer.

a.Measure the A.C. voltage on the transformer. If the A.C. voltage is 24 volts ± 15%, the transformer is good.

b.If the A.C. voltage is low, remove one secondary lead from its load connection.

1)If the A.C. voltage returns to 24V, the transformer is good.

2)If the A.C. voltage remains low, check the primary voltage. It should measure 240 or 480 volts A.C. accordingly ± 10%. If the primary voltage is correct, replace the transformer.

5.If the transformer is good, follow the voltage path using the wiring diagram. Check each control for voltage in and out. Replace where voltage fails.

Symptom—Boiler does not shut down

One or more contactors remain on after call for heat ends.

1.Check contactors. Lower the temperature setting on“high”side of the limit control to simulate a limit operation.

a.If all contactors instantly de-energize, they are good.

b.If one or more contactors fail to de-energize, replace those contactors.

2.If contactors are good, check the thermal delays. Return the temperature setting on the “high” side of the limit control to its original position. Allow the boiler to sequence on with a normal call for heat. When all contactors are energized, lower the setting on the “low” side of the limit control to satisfy the call for heat. Observe the shutdown sequence and note the contactor at which it stops. Remove the wire connecting terminal 1 of the electronic delay to the thermal delay: The contactor will now de-energize, and the remaining contactors will follow in the normal off sequence. Replace the defective thermal delay.

Symptom—Low heat

One or more contactors do not energize. Operation of any contactor, beyond the first is dependent upon the operation of three components.

•Thermal time delay.

•Electronic time delay; 2½ minutes.

•Contactor.

1.Observe the sequence of operation and note at which contactor it is interrupted. If one contactor fails to energize because of an open coil, subsequent contactors will be affected (unless one has a shorted coil). To isolate the trouble, proceed as follows:

a.Check contactor. Connect a jumper from terminal 3 of the electronic delay to the transformer wire going to terminal “B” on the “low” side of the limit control.

b.If the contactor energizes check electronic and thermal delays. Remove the jumper from the transformer terminal and touch it to terminal 1 of the electronic delay. (The jumper now connects terminals 1 and 3 of the electronic delay). If the contactor energizes, replace the electronic time delay. If it fails to energize, replace the thermal time delay.

Symptom—Inoperative circulator

1.Measure the voltage at the circulator terminals with the boiler energized. If the voltage is 120V ± 10%, the control is good. If no voltage is present, replace the circulator relay (1K).

Part number 550-141-396/0801 7