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| SECTION 9: TROUBLESHOOTING |
Pressure switch does not | Check flue/air supply duct for obstructions; remove any obstructions. | |
operate. | Check for loose/leaky air hoses to the pressure switch; repair/ | |
| replace/tighten hoses as required. Check for 24V across the secondary | |
| terminals 4 and 5 (red and yellow wires) of the transformer. | |
| IF NO: Check for 120V across the primary terminals 1 and 3 (black and | |
| white wires) of the transformer. If 120V is present, replace | |
| transformer. If 120V is not present, check wiring between power | |
| cord, blower motor and transformer. | |
| IF YES:Connect a jumper wire across pressure switch terminals; if jumper | |
| wire allows blower to operate, replace pressure switch | |
| (See Page 45, Section 12.1.1 for part number that applies to your | |
| unit rating). Do not resume normal heater operation until | |
| replacement pressure switch has been installed. | |
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Igniter spark gap incorrect. | Reset spark gap to 1/8" (3.175 mm). | |
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BURNER DOES NOT LIGHT |
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Possible Cause | Try this.... |
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Air in the gas line. | Purge gas lines. |
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Improper gas inlet pressure. | Check gas inlet pressure at the supply line. Gas inlet pressure should be | |
| as follows: |
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| Natural Gas: 5.0" w.c. (12.4 mbar) minimum; | |
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| 14.0" w.c. (34.8 mbar) maximum |
| LP Gas: | 11.0" w.c. (27.4 mbar) minimum; |
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| 14.0" w.c. (34.8 mbar) maximum |
| If gas inlet pressure does not meet inlet pressure requirements, contact | |
| the gas company. | |
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Gas valve does not open.
Check for 24V across valve terminals.
IF NO: Check wiring between the ignition module and the valve. Repair/ replace wires as required. If wiring is OK, replace ignition module.
IF YES: Replace gas valve.
Low gas outlet pressure. | Check gas manifold pressure. Measure manifold pressure at the pressure | |
| tap on the gas valve. See Page 35, Figure 33 and Page 38, Figure 34. | |
| Natural Gas: | 3.5" w.c. (8.7 mbar) |
| LP Gas: | 10.5" w.c. (26.1 mbar) |
If manifold pressure does not meet requirements, adjust valve outlet pressure with the adjustment screw on the valve.
NOTE: Proper inlet gas pressure must be verified before performing outlet pressure testing.
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