Troubleshooting a Warm-Air Heating System

Troubleshooting recommendations for a warm-air heating sys­tem will vary depending on the furnace make and model, and the type of installation. Always read and carefully follow the furnace
manufacturer’s troubleshooting recommendations if an operating manual is available. This troubleshooting section contains gen­eral remedies for common operating problems and their causes (Table 6-1).

Table 6-1

Troubleshooting Warm — Air Heating System

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Symptom and Possible Causes

No heat

1. Power may be off. Check fuse box or circuit breaker panel for blown fuses or tripped breakers.

2. Check thermostat (programmable type) for dead batteries.

Insufficient heat

1. Incorrect thermostat setting

2. Dirty filters

3. Poor air circulation

4. Open circuit

5. Main power switch off

6. Blocked outdoor coil (split system heating/cooling)

7. Air flow into intake and exhaust pipes of 90%-type furnace blocked

Suggested Remedies

1. Replace fuses or reset breakers. If the problem continues, call an electrician or an HVAC technician.

2. Replace batteries and reset thermostat.

1. Set thermostat above desired room temperature. Set the system switch on the thermostat to HEAT or AUTO.

2. Clean or replace filters.

3. Check supply registers and return grilles for blockage.

4. Reset circuit.

5. Turn main power switch to ON position.

6. Clear away blockage from outdoor coil.

7. Clear debris, ice, or snow from outdoor PVC pipes.

(continued)

Blower not operating

1. Fan switch setting

2. Blower door not completely closed

1. Set the fan switch to AUTO if you want the blower to function only while the furnace is operating; set it to ON for continuous operation.

2. Close blower door to restore power.

Table 6-1 (continued)

Symptom and Possible Causes

Humidity levels too low

1. Incorrect dehumidistat setting

2. Incorrect humidifier setting

3. Thermostat fan switch set on manual

4. Furnace ventilation switch set on continuous (low)

Humidity levels too high

1. Incorrect dehumidistat setting

2. No dehumidistat

3. Thermostat fan switch set on automatic

4. Furnace ventilation switch set on automatic

Suggested Remedies

1. Check setting and correct if necessary.

2. Check setting and correct if necessary.

3. Change setting to automatic.

4. Change setting to automatic.

1. Check setting and correct if necessary.

2. Install dehumidistat if necessary.

3. Change setting to manual.

4. Change setting to continuous (low).

Posted in Audel HVAC Fundamentals Volume 1 Heating Systems, Furnaces, and Boilers