Heater Not Firing
Fix pool heater ignition problems and restore heating
Common Heater Problems
🔥 Ignition Issues
- • Heater won't start
- • No pilot light
- • Igniter not sparking
- • Flame sensor problems
⚠️ Safety Shutoffs
- • Low water flow
- • High temperature limit
- • Gas pressure issues
- • Ventilation problems
Quick Answer
Pool heaters won't fire due to safety shutoffs, gas supply issues, or ignition system failures. First verify the heater has power and thermostat is calling for heat. Check that pump is running with adequate flow - low flow prevents ignition. Ensure gas supply is on and pilot light is lit if applicable. Most heater problems require professional diagnosis due to gas and electrical safety concerns.
Professional service recommended for this issue
Gas Heater Safety Warning
- •Pool heaters use natural gas or propane - both are explosive
- •If you smell gas, shut off supply immediately and call professional
- •Never bypass safety switches or controls
- •Carbon monoxide from improper combustion can be deadly
- •Only licensed technicians should service gas appliances
- •Ensure proper ventilation around outdoor heaters
If you smell gas: EVACUATE immediately and call your gas company's emergency line
How Pool Heaters Work
Heater Operation Sequence
- 1. Call for heat: Thermostat detects low water temperature
- 2. Safety checks: Flow, pressure, and limit switches verified
- 3. Ignition sequence: Gas valve opens, igniter activates
- 4. Flame detection: Sensor confirms combustion
- 5. Heat exchange: Hot gases warm water in tubes
- 6. Temperature control: Cycles on/off to maintain setpoint
Safety Features
- • Flow switch: Prevents firing without water flow
- • Pressure switch: Verifies adequate system pressure
- • High limit: Shuts off if water gets too hot
- • Flame sensor: Ensures proper combustion
- • Vent sensor: Monitors exhaust temperatures
- • Gas valve: Automatic shutoff on fault
Key Point:
Modern heaters have multiple safety interlocks. If any safety device detects a problem, the heater won't fire. This protects against dangerous conditions but requires proper diagnosis.
Heater Troubleshooting Process
Step-by-Step Diagnosis
Check Power and Controls
Verify heater has power, thermostat is set above water temperature, and heater switch is on.
Verify Water Flow
Check pump is running and filter pressure is normal. Heaters require minimum flow to operate.
⚠️ Warning: Low flow triggers safety shutoff - never bypass flow switches
Check Gas Supply
Verify gas valve is open, pilot light is lit (if applicable), and other gas appliances work.
⚠️ Warning: Gas leaks are dangerous - if you smell gas, shut off supply and call professional
Review Error Codes
Check display panel for error codes. Note any flashing lights or fault indicators.
Inspect Safety Switches
Check pressure switch, high limit switch, and flow switch for proper operation.
⚠️ Warning: Never bypass safety switches - they prevent dangerous conditions
Test Ignition System
Listen for ignition sequence. Check for spark or glow depending on ignition type.
⚠️ Warning: Ignition system testing should only be done by qualified technicians
Common Reasons Heaters Won't Fire
Low Water Flow
Problem:
Insufficient flow triggers safety shutoff to prevent overheating
Check:
Pump running, filter clean, valves open, no blockages
Solution:
Clean filter, check pump operation, verify valve positions
Thermostat Issues
Problem:
Thermostat not calling for heat or set below water temperature
Check:
Temperature setting, actual water temp, thermostat calibration
Solution:
Adjust setpoint higher, calibrate or replace faulty thermostat
Gas Supply Problems
Problem:
No gas reaching burner due to closed valve or empty tank
Check:
Gas valve open, propane tank level, other gas appliances
Solution:
Open gas valve, refill propane, check gas meter
Ignition System Failure
Problem:
Electronic igniter, pilot light, or flame sensor malfunction
Signs:
No spark, pilot won't stay lit, flame sensor dirty
Solution:
Professional igniter replacement or flame sensor cleaning
Safety Switch Tripped
Problem:
High limit, pressure switch, or vent switch detecting unsafe condition
Causes:
Overheating, low pressure, blocked vents, scale buildup
Solution:
Address underlying issue, reset switch if safe
Pool Heater Types & Common Brands
Natural Draft Heaters
How they work: Atmospheric combustion with pilot light
Common brands: Raypak, Pentair MiniMax
Typical issues: Pilot light problems, thermocouple failure
Efficiency: 78-82% typical
Note: Being phased out for low NOx models
Electronic Ignition Heaters
How they work: Hot surface or spark ignition
Common brands: Hayward Universal, Jandy LXi
Typical issues: Igniter failure, control board problems
Efficiency: 82-95% depending on model
Benefit: No pilot light to maintain
Heat Pump Heaters
How they work: Extract heat from air like AC in reverse
Common brands: Pentair UltraTemp, Hayward HeatPro
Typical issues: Refrigerant leaks, compressor failure
Efficiency: 500-600% (COP 5-6)
Best for: Mild climates, year-round heating
Low NOx Heaters
How they work: Advanced combustion for low emissions
Common brands: Raypak AVIA, Pentair MasterTemp
Typical issues: Complex controls, sensor problems
Efficiency: 82-84% typical
Required: In many areas for emissions
Common Heater Error Codes
Error codes vary by manufacturer. Always consult your manual for specific codes.
Common Error Types:
- • Ignition Failure: Multiple failed ignition attempts
- • Flame Failure: Flame lost during operation
- • High Limit: Water temperature too high
- • Pressure/Flow: Insufficient water flow
- • Sensor Fault: Temperature sensor problems
- • Gas Pressure: Low or high gas pressure
Typical Indicators:
- • LED Flashes: Count flashes for code
- • Digital Display: Shows error number
- • Service Light: Indicates service needed
- • Lockout Mode: Requires manual reset
- • Diagnostic Mode: Special test sequence
- • History Log: Stores recent faults
Heater Repair Costs
Heater Service & Repair Costs
🔧 DIY Attempt
⚠️ Risks:
- • Gas explosion from improper handling
- • Carbon monoxide poisoning
- • Electrical shock from control circuits
- • Voiding warranty and insurance
- • Creating more expensive damage
👷 Professional Service
✅ Includes:
- • Complete diagnostic testing
- • Gas pressure and combustion analysis
- • Ignition system service or replacement
- • Safety control testing and adjustment
- • Heat exchanger inspection
- • Warranty on parts and labor
💰 Value Tip: CoOpPools offers transparent pricing with no hidden fees. Our worker-owned model means fair prices and invested service.
Prevent Heater Problems
Prevention Tips
Annual Professional Service
Have heater cleaned, adjusted, and safety-tested before each heating season
Maintain Proper Water Chemistry
Keep pH 7.2-7.6 and calcium 200-400 ppm to prevent heat exchanger damage
Regular Filter Maintenance
Clean filter regularly to maintain proper flow through heater
Cover Heater When Not in Use
Protect from weather and debris during off-season with proper cover
Monitor for Warning Signs
Address soot, rust, or unusual sounds before complete failure
🏊 Pro Tip: Regular professional maintenance prevents 90% of pool problems.Get your maintenance quote today
This Issue Requires Professional Service
Pool heater won't fire? Our certified heater technicians diagnose and repair all brands of gas heaters. We provide safe, professional service including ignition system repair, gas pressure testing, safety control verification, and complete heater maintenance. Don't risk gas appliance repairs - call the experts.
Mention "heater ignition problems" when calling for faster service
Related Pool Problems
Related Pool Problems
Heater Short Cycling
Often RelatedHeater turns on and off repeatedly
Low Water Flow
Sometimes RelatedInsufficient flow prevents heater operation
Equipment Malfunction
Sometimes RelatedGeneral equipment troubleshooting
💡 Did You Know? Pool problems often occur together.Heater Not Firing can lead to or be caused by these related issues. Understanding the connections helps prevent future problems.