Heater Ignition Failure
Diagnose and fix heaters that won't light or have delayed ignition
Quick Answer
Heater ignition failures are caused by faulty ignitors (40%), dirty flame sensors (30%), gas supply issues (20%), or control problems (10%). Symptoms include no ignition attempts, sparking without lighting, or delayed/explosive ignition. While cleaning flame sensors is possible DIY, most ignition repairs require professional service for safety.
Professional service recommended for this issue
Understanding Pool Heater Ignition Systems
Modern Electronic Ignition
- • Hot surface ignitor: Glows to ignite gas
- • Spark ignition: Creates spark to light gas
- • Flame sensor: Proves flame presence
- • Control board: Manages sequence
- • Safety lockout: Prevents gas buildup
- • No pilot light: More efficient
Ignition Sequence
- Call for heat: Thermostat signals
- Safety check: Verify all limits OK
- Pre-purge: Clear combustion chamber
- Ignitor activation: Heat or spark
- Gas valve opens: Fuel flows
- Flame proof: Sensor confirms ignition
Safety Note: Modern heaters have 3-5 ignition attempts before lockout. This prevents dangerous gas accumulation from repeated failures.
Common Ignition Failure Types
No Ignition Attempt
Symptoms:
- • No clicking or sparking sounds
- • Ignitor doesn't glow/spark
- • Immediate error code
- • No gas valve operation
- • Blower may not start
Common Causes:
- • Control board failure
- • Safety circuit open
- • No power to ignitor
- • Limit switch tripped
- • Pressure switch error
Action: Check basic power and safety systems before condemning ignitor.
Sparks/Glows But Won't Light
Symptoms:
- • Ignitor activates properly
- • No flame establishment
- • Multiple failed attempts
- • System locks out
- • Gas valve may not open
Common Causes:
- • No gas supply
- • Clogged orifices
- • Gas valve failure
- • Wrong gas type
- • Air in gas line
Check: Verify gas supply at meter and test other gas appliances.
Delayed/Explosive Ignition
Dangerous Signs:
- • Loud bang when lighting
- • Flame rollout from chamber
- • Vibration on ignition
- • Soot on heater front
- • Smell of gas before ignition
Causes:
- • Weak ignitor
- • Ignitor misalignment
- • Low gas pressure
- • Dirty burners
- • Control timing issues
DANGER: Delayed ignition can cause explosions. Stop use immediately and call professional.
Intermittent Failures
Pattern:
- • Works sometimes
- • Fails when hot/cold
- • Multiple attempts needed
- • Gets worse over time
- • Weather dependent
Typical Causes:
- • Failing ignitor
- • Marginal flame sensor
- • Loose connections
- • Borderline gas pressure
- • Control board issues
Note: Intermittent problems worsen quickly. Address before complete failure.
Ignition Component Details
Hot Surface Ignitors (HSI)
Silicon carbide or nitride element that glows orange to ignite gas.
- • Lifespan: 3-7 years
- • Fragile when hot
- • 120V operation typical
- • Cracks with age
Failure Signs:
- • Doesn't glow bright orange
- • Visible cracks or breaks
- • Slow to heat up
- • Measures high resistance
Spark Ignitors
Creates high voltage spark to ignite gas, similar to spark plug.
- • Lifespan: 5-10 years
- • More durable than HSI
- • Requires proper gap
- • 10,000+ volt spark
Failure Signs:
- • Weak or no spark
- • Corroded electrode
- • Cracked insulator
- • Improper gap
Flame Sensors
Metal rod that detects flame presence through flame rectification.
- • Generates microamps
- • Must be in flame
- • Requires cleaning
- • Simple but critical
Maintenance:
- • Clean with fine sandpaper
- • Remove carbon buildup
- • Check positioning
- • Test microamp output
Ignition System Safety
- •Failed ignition attempts can fill combustion chamber with gas - explosion risk
- •Never bypass safety controls or flame sensors - fire and CO poisoning hazards
- •Delayed ignition creates dangerous pressure waves that damage equipment
- •Hot surface ignitors operate at 2000°F - severe burn risk when hot
- •High voltage spark systems can cause fatal electrical shock
- •Only licensed technicians should service gas ignition systems
If you smell gas: EVACUATE immediately and call your gas company's emergency line
Safe DIY Maintenance
You Can Safely:
- ✓ Keep burner area free of debris
- ✓ Check for spider webs monthly
- ✓ Listen for normal ignition sounds
- ✓ Note any changes in startup
- ✓ Keep heater cabinet closed
- ✓ Schedule annual service
Leave to Professionals:
- ✗ Ignitor replacement or testing
- ✗ Flame sensor cleaning/replacement
- ✗ Gas valve troubleshooting
- ✗ Control board diagnosis
- ✗ Any internal heater work
- ✗ Addressing delayed ignition
Flame Sensor Tip: While some DIY guides suggest cleaning flame sensors, improper handling can damage the rod or create safety issues. Professional cleaning during annual service is safer and includes proper testing.
Professional Ignition System Diagnosis
Verify Basic Requirements
Check fundamental needs for ignition
⚠️ Warning: Never attempt ignition with gas odors present - evacuate and call emergency services
Observe Ignition Sequence
Watch and listen to startup attempts
⚠️ Warning: Multiple failed ignitions can flood combustion chamber with gas
Inspect Ignition Components
Visual check of ignitor and flame sensor
⚠️ Warning: High voltage present at ignitor - turn off power before inspection
Test for Delayed Ignition
Identify dangerous delayed lighting
⚠️ Warning: Delayed ignition can cause explosions - professional service required
Check Gas Supply Quality
Verify adequate gas pressure and flow
⚠️ Warning: Gas pressure testing requires licensed technician with proper gauges
Professional Electronic Testing
Advanced diagnosis of control systems
⚠️ Warning: Electronic testing requires specialized knowledge and equipment
Ignition System Repair Costs
🔧 DIY Attempt
⚠️ Risks:
- • Gas explosion from improper diagnosis or repair attempts
- • Electrical shock from ignition system high voltage
- • Carbon monoxide poisoning from incomplete combustion
- • Fire hazard from gas leaks or improper repairs
- • Voiding warranty and insurance with DIY gas work
👷 Professional Service
✅ Includes:
- • Complete ignition system diagnosis
- • Ignitor testing and replacement if needed
- • Flame sensor cleaning or replacement
- • Gas pressure and flow verification
- • Control board testing and programming
- • Safety system verification
Detailed Cost Breakdown
| Item/Service | Low | High |
|---|---|---|
| Service call and diagnosis | $125 | $200 |
| Hot surface ignitor replacement | $200 | $400 |
| Spark ignitor replacement | $250 | $450 |
| Flame sensor replacement | $150 | $250 |
| Control board replacement | $400 | $800 |
| Gas valve replacement | $300 | $600 |
| Total Range | $1425 | $2700 |
💰 Value Tip: CoOpPools offers transparent pricing with no hidden fees. Our worker-owned model means fair prices and invested service.
Prevention Tips
Annual Ignition System Service
Professional cleaning of ignitor and flame sensor prevents most failures. Include burner cleaning and ignition timing check.
Keep Burner Area Clean
Remove spider webs and debris from burner compartment monthly. Blockages cause ignition failures and dangerous conditions.
Monitor Ignition Performance
Watch for slower lighting or multiple attempts. Early detection prevents complete failure and safety hazards.
Protect from Moisture
Ensure heater cabinet seals properly. Moisture damages ignitors and causes corrosion leading to failures.
Replace Ignitors Proactively
Consider replacing hot surface ignitors every 5-7 years. Preventive replacement avoids unexpected failures.
🏊 Pro Tip: Regular professional maintenance prevents 90% of pool problems.Get your maintenance quote today
This Issue Requires Professional Service
Ignition problems involve gas and electrical systems requiring professional expertise. Our certified technicians safely diagnose and repair all ignition issues, from simple sensor cleaning to complex control problems, ensuring reliable and safe heater operation.
Mention "heater ignition failures" when calling for faster service
Related Pool Problems
Heater Won't Ignite
Often RelatedSimilar ignition problems with different causes
Pilot Light Won't Stay Lit
Often RelatedPilot ignition issues in older heaters
Heater Error Codes
Sometimes RelatedIgnition error codes explained
💡 Did You Know? Pool problems often occur together.heater-ignition-failure can lead to or be caused by these related issues. Understanding the connections helps prevent future problems.