Specifications
Diagnostics
GAND-SVX01B-EN 37
F. Gas Odor. 1. Shut off gas supply
immediately!
1. Inspect all gas piping and repair.
2. Blocked heat exchanger/venting. 2. Clean heat exchanger/flue.
3. Drafts around heater. 3. Eliminate drafts. Refer to “Installation: Mechanical,” p. 12.
4. Negative pressure in building. 4. See “Installation: Piping,” p. 16.
5. Blocked flue collector. 5. Clean flue collector.
G. Delayed ignition. 1. Excessive primary air. 1. Close air shutter. Refer to “Operation,” p. 26.
2. Main burner ports clogged near
pilot.
2. Clean main burner ports.
3. Pressure regulator set too low. 3. Reset manifold pressure. Refer to “Operation,” p. 26.
4. Pilot decreases in size when main
burners come on.
4. Supply piping is inadequately sized. Refer to “Installation:
Piping,” p. 16.
5. Pilot flame too small. 5. Clean pilot orifice. Refer to “Operation,” p. 26.
6. Drafts around heater. 6. Eliminate drafts. Refer to “Installation: Mechanical,” p. 12.
7. Improper venting. 7. Refer to “Installation: Piping,” p. 16.
H. Failure to ignite. 1. Main gas off. 1. Open all manual gas valves.
2. Lack of power at unit. 2. Replace fuse or turn on power supply.
3. Thermostat not calling for heat. 3. Turn up thermostat.
4. Defective limit switch. 4. Check limit switch with continuity tester. If open, replace
limit switch.
5. Improper thermostat or
transformer wiring.
5. Check wiring per diagrams.
6. Defective gas valve. 6. Replace gas valve.
7. Defective thermostat. 7. Check thermostat and replace if defective.
8. Defective transformer. 8. Be sure 115 volts is supplied to the transformer primary,
then check for 24 volts at secondary terminal before
replacing.
9. Loose wiring. 9. Check and tighten all wiring connections per diagrams.
10. Defective ignition control. 10. Replace, if necessary. Also see U, V, and W symptoms.
I. Condensation of water vapor. 1. Improper venting 1. Refer to “Installation: Venting,” p. 18.
J. Burner won't turn off. 1. Poor thermostat location. 1. Relocate thermostat away from drafts.
2. Defective thermostat. 2. Replace thermostat.
3. Improper thermostat or
transformer wiring at gas valve.
3. Check wiring per diagrams.
4. Short circuit. 4. Check operation at valve. Check for short (such as staples
piercing thermostat wiring), and correct.
5. Defective or sticking gas valve. 5. Replace gas valve.
6. Excessive gas supply pressure. 6. Refer to “Installation: Piping,” p. 16.
K. Rapid burner cycling. 1. Loose electrical connections at gas
valve or thermostat.
1. Tighten all electrical connections.
2. Excessive thermostat heat
anticipator.
2. Adjust thermostat heat anticipator for longer cycles. Refer
to “Installation: Electrical,” p. 24.
3. Unit cycling on high limit. 3. Check for proper air supply across heat exchanger.
4. Poor thermostat location. 4. Relocate thermostat. (Do not mount thermostat on unit).
5. Draft on pilot. 5. Eliminate drafts. Refer to “Installation: Mechanical,” p. 12.
6. Defective ignitor control. 6. Replace ignitor.
7. Defective high limit switch. 7. Jumper high limit switch terminals 1 and 2. If burner
operates normally, replace switch.
L. Noisy. 1. Fan blades loose. 1. Replace or tighten.
2. Fan blades dirty. 2. Clean fan wheel.
3. Vibration isolators deteriorated. 3. Replace vibration isolators.
4. Bearings are dry. 4. Oil bearings on fan motor. (Refer to label on motor.)
M. Pilot will not light or will not stay
lit.
1. Main gas off. 1. Open all manual gas valves.
Table 7. Troubleshooting guide (continued)
Symptoms Possible Cause(s) Corrective Action