Rheem Furnace Error Code 22 commonly appears on Rheem gas furnaces to indicate an ignition problem, often related to a failed or intermittent flame detection. This article explains causes, step-by-step troubleshooting, parts to inspect, safety precautions, and when to call a professional technician to resolve the issue safely and effectively.
| Item | Quick Summary |
|---|---|
| Error Code | 22 — Ignition/Flame Failure or Flame Signal Fault |
| Common Causes | Dirty flame sensor, bad igniter, gas supply issues, control board or grounding problem |
| DIY Steps | Reset, clean flame sensor, inspect igniter, check gas, verify venting and pressure |
| When To Call Pro | Gas smell, repeated resets, electrical component failure, gas valve or control board replacement |
What Error Code 22 Means
Error Code 22 on Rheem furnaces signals that the control board did not detect a stable flame during the ignition sequence or the flame signal was lost shortly after ignition. This is primarily an ignition or flame-detection fault rather than a temperature or thermostat issue.
How Rheem Controls Detect Flame
Rheem furnaces typically use a hot surface igniter or spark igniter combined with a flame sensor or flame rectification system. The control board looks for a small electrical signal from the flame sensor indicating combustion. If the signal is absent or unstable, the board locks out and shows error code 22.
Common Causes Of Error Code 22
Understanding the root causes helps prioritize troubleshooting. Common issues include:
- Dirty Or Corroded Flame Sensor: A coated sensor cannot detect the flame properly.
- Faulty Igniter: Cracked or weak hot-surface igniters fail to light the burners reliably.
- Gas Supply Problems: Closed gas valve, low gas pressure, or interrupted fuel flow prevents a steady flame.
- Ignition Control Or Circuit Board Faults: Defective control boards, wiring faults, or poor grounding can disrupt flame detection.
- Ventilation Or Combustion Air Issues: Blocked vents or exhaust problems affect combustion stability.
- Flame Rollout Or Safety Switches: Limit switches or rollout sensors can interrupt ignition if they detect unsafe conditions.
Safety First: Before Troubleshooting
Before attempting any diagnostic steps, ensure safety. Turn off power to the furnace at the breaker and shut off gas if working near gas components. If a strong gas odor exists, leave the building immediately and call the gas company and emergency services.
Basic Reset And Observation
Start with a basic reset because a transient issue can sometimes clear. Turn the furnace off at the thermostat, switch off power at the breaker for 60 seconds, then restore power and call for heat. Watch the ignition sequence and note whether the igniter glows, burners light, and the flame sensor registers continuously.
Cleaning The Flame Sensor
A dirty flame sensor is the most common homeowner-fixable cause of error code 22. Steps: turn off power, remove the sensor (a single screw), and gently clean the metal rod with fine emery cloth or 400-grit sandpaper until shiny. Reinstall, restore power, and test the furnace. Cleaning often restores proper flame sensing.
Inspecting And Testing The Igniter
If cleaning the flame sensor does not resolve the code, inspect the igniter visually for cracks, white powder, or brittle areas. A cracked hot surface igniter will need replacement. Use a multimeter to test continuity if comfortable; many igniters show specific resistance values listed on the furnace documentation.
Checking Gas Supply And Valve
Verify that the gas valve to the furnace is open and other gas appliances work. Low gas pressure or a stuck valve can prevent sustained flame. If a gas smell or irregular burner behavior occurs, stop and call a licensed HVAC or gas professional. Never attempt to repair gas valves without proper credentials.
Examining Burners And Flame Pattern
Inspect burners for dirt, rust, or misalignment. Clean burner ports with a soft brush if clogged. A proper flame should be steady and mostly blue with minimal yellow tips. Yellow, lifting, or irregular flames indicate combustion issues that can trigger error code 22.
Testing Wiring, Grounding, And Flame Signal
Loose connections, damaged wiring, or poor chassis grounding can interrupt the flame signal. Inspect the wiring harness between the flame sensor, igniter, and control board for corrosion or loose terminals. Use a multimeter to check continuity and proper voltage if qualified. Secure and clean any suspect connectors.
Control Board And Error Log
Control board failure or firmware issues can misinterpret signals. Review the furnace’s diagnostic LED sequence and error history if available. Some Rheem models allow viewing recent codes which helps determine if error 22 is intermittent or persistent. A repeated code after component checks suggests a control board replacement may be needed.
When Venting Or Pressure Switches Cause Problems
Blocked venting, flue issues, or a failing pressure switch can prevent proper combustion and trigger flame detection faults. Check for obstructions at intake and exhaust pipes, ensure condensate lines are clear, and test the pressure switch tubing for cracks or disconnections.
Advanced Diagnostics: What Technicians Do
HVAC technicians use specialized tools to measure flame signal millivolts, gas manifold pressure, and ignition circuit behavior. They will test the flame sensor output, inspect the control board relays, and verify proper sequencing according to the furnace schematic. Technicians also confirm safety interlocks and combustion metrics.
Parts That Commonly Need Replacement
Frequent replacements for resolving error code 22 include the flame sensor, hot surface igniter, gas valve assembly, and occasionally the control board. Technicians may replace connectors or wiring harnesses when corrosion or intermittent continuity is found.
Costs And Time Estimates
Costs vary by part and region. Cleaning a flame sensor is often inexpensive or DIY. Igniter replacement typically ranges from moderate to higher cost depending on model and labor. Control board or gas valve replacements are more costly. A qualified technician can diagnose and often repair the issue within one service visit.
When To Call A Professional
Call a licensed HVAC technician when: a gas leak is suspected, multiple resets fail, electrical diagnostics are required, or major components such as gas valve or control board are suspected. Professional intervention ensures safe handling of gas and electrical systems.
Preventive Maintenance To Avoid Error 22
- Schedule annual furnace maintenance and combustion tune-ups.
- Keep the furnace area clean and unobstructed for proper airflow.
- Replace air filters regularly to reduce dust buildup on burners and sensors.
- Inspect vents and chimneys seasonally for blockages or bird nests.
Frequently Asked Questions (FAQ)
Can a Furnace Be Restarted After Error Code 22?
Yes, a manual or power reset can clear a transient code, but if the error returns, further diagnostics are required. Repeated resets without fixing the cause can damage components.
How Long Does Cleaning The Flame Sensor Take?
Cleaning the flame sensor typically takes 10–20 minutes including power down and reassembly. It is a common and effective first step for error code 22.
Is Error Code 22 Dangerous?
Error code 22 itself indicates an ignition or flame detection fault, not an immediate danger, but underlying causes like gas leaks or faulty valves can be hazardous. If any gas odor or unsafe condition is present, evacuate and call professionals.
Does Replacing The Control Board Always Fix It?
Not always. Replacing the control board without diagnosing underlying issues like faulty sensors, wiring, or gas problems may not resolve error code 22. Proper diagnostics should precede board replacement.
Useful Links And Resources
Consult the furnace model’s installation and service manual for wiring diagrams and error code definitions. Rheem’s official support pages and user manuals provide model-specific guidance and part numbers. For gas safety issues, consult local utility company resources.
Key Takeaways
Error Code 22 Points To An Ignition Or Flame Detection Problem. Start with a reset and clean the flame sensor. Inspect the igniter, burners, gas supply, wiring, and venting. Use caution around gas and electrical components. Call a licensed HVAC technician for persistent issues or suspected gas component failures.