Troubleshooting

Control Supplement — Standing Pilot Boilers

Verify proper operation after servicing

Never jumper (bypass) any device except for momentary testing as outlined in troubleshooting chart below. Substantial property damage and/or severe personal injury could occur.

Burner access panel must be in position during boiler operation to prevent momentary flame rollout on ignition of main flame. Severe personal injury or substantial property damage will result.

Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous operation leading to 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.Be sure pilot is lit. See “Lighting instructions” on page 12 for details.

4.Make sure thermostat is calling for heat and contacts (including appropriate zone controls) are closed. Check for 24VAC between thermostat wire nuts and ground.

Pilot does not stay lit — Troubleshooting thermopile and high limit control circuit

1.Checking thermopile open system (Figure 5):

a.Use an electronic multimeter, with leads fitted with alligator clips. Set meter scale to DC Millivolts.

b.Unscrew thermopile fitting from gas valve.

c.Attach one meter lead to the end of the thermopile gas valve fitting.

d.Attach other meter lead to thermopile lead (copper surface).

e.Follow Lighting Instruction label on boiler (also found in Control Supplement or User’s Information manual) to light the pilot burner only and hold the pilot flame manually. (DO NOT light main burner.)

f.Check the reading on the multimeter. The reading should be around 700 millivolts.

g.If multimeter reading is significantly less than above, replace the thermopile.

2.Checking thermopile circuit closed system (Figure 6):

a.Use an electronic multimeter, with leads fitted with alligator clips. Set meter scale to DC Millivolts.

b.Loosen the insulated terminal on the TOP thermopile lead wire enough to allow clipping a multimeter alligator clip to the spade terminal.

c.Attach the other multimeter lead to the thermopile lead.

d.Check the reading on the multimeter. The reading should be around 400 millivolts.

e.If reading is significantly less than 400 millivolts, check tightness of lead wire assembly in gas valve. If the connections are secure and you

have checked the thermopile per step 1 above, replace the thermopile lead wire assembly.

f.If reading on TOP thermopile lead wire is around 400 millivolts, move the multimeter alligator clip to the BOTTOM thermopile lead wire terminal and check multimeter reading.

g.If multimeter does not read around 400 millivolts, check wiring connections and wire integrity to the limit controls.

h.Check voltage at each limit terminal to make sure limit is closed. Correct pressure or temperature condition causing any limit to be open. Replace limit if necessary.

Figure 5

Figure 6

Part Number 550-110-031/0605

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