Table 31 — Heating Service Analysis
PROBLEM | CAUSE | REMEDY |
Burners will not | Misaligned spark electrodes. | Check flame ignition and sensor electrode positioning. Adjust as |
ignite. |
| needed. |
| No gas at main burners. | Check gas line for air purge as necessary. After purging gas line of |
|
| air, allow gas to dissipate for at least 5 minutes before attempting to |
|
| relight unit. |
|
| Check gas valve. |
| Water in gas line. | Drain water and install drip leg to trap water. |
| No power to furnace. | Check power supply, fuses, wiring, and circuit breaker. |
| No 24 v power supply to control circuit. | Check transformer. Transformers with internal overcurrent protection |
|
| require a |
|
| breaker; reset if necessary. |
| Miswired or loose connections. | Check all wiring and wirenut connections. |
| Replace thermostat. | |
| Broken thermostat wires. | Run continuity check. Replace wires, if necessary. |
Inadequate heating. | Dirty air filter. | Clean or replace filter as necessary. |
| Gas input to unit too low. | Check gas pressure at manifold. Clock gas meter for input. If too low, |
|
| increase manifold pressure or replace with correct orifices. |
| Unit undersized for application. | Replace with proper unit or add additional unit. |
| Restricted airflow. | Clean filter, replace filter, or remove any restrictions. |
| Blower speed too low. | Use high speed tap, increase fan speed, or install optional blower, as |
|
| suitable for individual units, Adjust pulley. |
| Limit switch cycles main burners. | Check rotation of blower, thermostat heat anticipator settings, and |
|
| temperature rise of unit. Adjust as needed. |
| Too much outdoor air. | Adjust minimum position. |
|
| Check economizer operation. |
Poor flame | Incomplete combustion (lack of | Check all screws around flue outlets and burner compartment. |
characteristics. | combustion air) results in: | Tighten as necessary. |
| Aldehyde odors, CO (carbon monoxide), | Cracked heat exchanger. |
| sooting flame, or floating flame. | Overfired unit — reduce input, change orifices, or adjust gas line or |
|
| |
|
| manifold pressure. |
|
| Check vent for restriction. Clean as necessary. |
|
| Check orifice to burner alignment. |
Burners will not | Unit is locked into Heating mode for a | Wait until mandatory one minute time period has elapsed or reset |
turn off. | one minute minimum. | power to unit. |
Table 32 — Durablade Economizer Service Analysis
PROBLEM | CAUSE |
| REMEDY | |
Damper does not | Evaporator fan not on. | Check wiring between G on connection board and | ||
open. |
| contactor. | ||
|
| No power to economizer motor. | 1. | Check that SW3 is making proper contact with the damper blade. |
|
|
| 2. | Check continually across R1 coil. If not connect, replace relay R1. |
|
|
| 3. | Check diode D18. If diode is not functioning properly, replace D18. |
|
|
| 4. | Check wiring in economizer relay pack. (See unit label diagram.) |
|
| Economizer motor failure. | If there is 24 vac power at the motor terminals, but motor is not operat- | |
|
|
| ing, replace motor. | |
Economizer | OAT or EC set too high. | 1. | Set at correct temperature (3 F below indoor space temperature). | |
operation limited to |
| 2. | Check OAT or EC by setting set point above outdoor temperature or | |
minimum position. |
|
| humidity level. If switch does not close, replace OAT or EC. | |
|
| Check wiring of economizer relay packs. | 1. | Check continuity across relay R2 coil. If not connected, replace R2 |
|
|
|
| relay. |
|
|
| 2. | Check continuity across relay R3 coil. If not connected, replace R3 |
|
|
|
| relay. |
|
| Check SAT. | If | |
|
|
| not, replace SAT. | |
Damper does not | Incorrect wiring or wiring defects. | 1. | Check switches 2 and 4. If | |
close. |
| 2. | Check diode D19. If diode D19 is not functioning properly, replace. | |
|
|
| 3. | Check wiring on economizer and on economizer relay pack. (See |
|
|
|
| unit label diagram.) |
|
| Check SAT. | If | |
|
|
| not, replace SAT. | |
|
| Economizer motor failure. | If there is 24 vac power at motor terminals, but motor is not operating, | |
|
|
| replace the motor. | |
LEGEND |
|
|
| |
EC — Enthalpy Control |
|
| ||
OAT — |
|
| ||
SAT — |
|
| ||
SW — Switch |
|
|
|
40