The Hayward H150 is a reliable gas pool heater designed to heat smaller to mid-sized pools efficiently. But like all pool equipment, it can occasionally develop issues that disrupt your swim season. This guide outlines the most common Hayward H150 pool heater problems and how to troubleshoot and fix them without unnecessary service calls.
Understanding the Hayward H150 Pool Heater
The H150 is part of Hayward’s H-Series and comes in standard and low NOx models. It operates using natural gas or propane, and features an electronic ignition, LED diagnostics, and temperature control. While user-friendly, a small issue—like a dirty sensor or incorrect gas pressure—can cause performance problems.
Let’s explore the top H150 heater issues, what causes them, and how to fix them.
Table of Contents
- Heater Not Starting or Powering On
- Ignition Failure (IF Code)
- Low Water Flow or LO Code
- Heater Overheating or HS Code
- Frequent Cycling or Random Shutoffs
- Strange Noises or Soot
- Gas Supply and Burner Issues
- Control Board and Display Issues
- Preventative Maintenance Checklist
- Conclusion & Next Steps
Heater Not Starting or Powering On
Answer: If your Hayward H150 won’t turn on at all, check the electrical power, circuit connections, and fuse.
Steps to troubleshoot:
- Verify breaker: Check the dedicated circuit breaker and GFCI outlet for resets.
- Confirm transformer voltage: The 24V transformer should deliver low voltage to the board—use a multimeter to confirm output.
- Inspect wiring: Loose or corroded wire terminals can block power to the control panel.
- Check internal fuse: Inside the control board, replace the 3-amp fuse if it’s blown.
Tip: If the display is dead but voltage is present, it’s likely a failed control board or transformer.
Ignition Failure (IF Code)
Answer: The IF code signals that the heater failed to ignite after multiple attempts. This usually relates to gas supply, igniter problems, or flame sensing failure.
- Gas valve open: Make sure the valve is fully open and the gas line is pressurized.
- Igniter condition: Visually inspect the igniter—replace if cracked or sooty.
- Flame sensor: Clean gently with steel wool. It must detect a flame or the system shuts down.
- Air in gas line: Especially after new installation or propane tank refill, purge line carefully.
Reminder: Always turn off power and gas before working on the ignition system.
Low Water Flow or LO Code
Answer: The LO code appears when water flow through the heater is inadequate, often due to clogged filters or a malfunctioning pressure switch.
- Clean filters: Backwash sand filters or rinse cartridge filters to restore flow.
- Inspect pump basket: Clogged pump baskets slow circulation.
- Check bypass valve: Ensure it allows enough flow through the heater.
- Test pressure switch: If water flow is fine, the switch may need replacement.
Tip: The pump should run at a minimum of 30 GPM for proper heater operation.
Heater Overheating or HS Code
Answer: If your heater throws the HS (High-Temperature Shutdown) code, water inside the heat exchanger may be getting too hot.
Likely causes:
- Restricted flow: Blocked return lines, valves, or closed bypasses lead to overheating.
- Thermostat failure: May misread water temperature and fail to cut off heat.
- Scale buildup: Hard water causes mineral scaling inside the exchanger, trapping heat.
- Stuck thermal regulator: Replace if it doesn’t modulate water temperature effectively.
Fix: Flush the exchanger with a descaling solution and inspect the high-limit switch for malfunction.
Frequent Cycling or Random Shutoffs
Answer: Short-cycling is when the heater turns on and off too frequently. This strains components and lowers efficiency.
- Water too warm: If your setpoint is close to pool temperature, the heater cycles more.
- Thermal regulator malfunction: Replacing it often fixes cycling issues.
- Poor flow rate: Ensure valves are open and pump speed is sufficient.
- Dirty filters: Can cause inconsistent pressure and flow.
Pro tip: Use a digital flow meter to verify water movement is steady and above minimum threshold.
Strange Noises or Soot
Answer: Unusual sounds like popping or a burning smell may indicate combustion problems, dirty burners, or sooting in the heat exchanger.
What to look for:
- Burner tray inspection: Remove and clean burners annually to prevent soot buildup.
- Vent blockages: Clear vent pipes and air intake to allow proper combustion.
- Flame rollout: If flames escape the front, turn off the heater immediately—it’s a fire hazard.
Fix: Use compressed air and a brush to clean the burner chamber and reinstall burners evenly.
Gas Supply and Burner Issues
Answer: A weak or yellow flame usually means poor combustion caused by low gas pressure or debris in the burner orifices.
- Check pressure: Have a technician measure input and manifold gas pressure.
- Clean burner orifices: Use a small wire brush and compressed air to remove spider webs or insects.
- Ventilation: Ensure enough outdoor air is reaching the combustion chamber.
Reminder: Gas line repairs and adjustments should always be performed by a licensed technician.
Control Board and Display Issues
Answer: Display malfunctions or control board failures can mimic other heater problems.
Symptoms include:
- Flickering or blank screen: Indicates power instability or internal board failure.
- Error codes not resetting: May require full board reset or replacement.
- False sensor readings: If sensors seem fine but errors persist, check wiring or board logic.
Fix: Reset the control board by disconnecting power for 2 minutes. If issues return, replace the board or wiring harness.
Preventative Maintenance Checklist
Keep your H150 heater running smoothly by following this seasonal maintenance routine:
- Spring: Clean flame sensor, test igniter, inspect burners and replace corroded parts.
- Summer: Check PSI and water flow weekly. Monitor error codes and clean filters regularly.
- Fall: Descale heat exchanger, clear vent and exhaust lines, inspect wiring for wear.
- Winter: Drain heater completely, disconnect gas line if necessary, and store covered in harsh climates.
Maintenance tip: Replace the pressure switch, flame sensor, and igniter every 3 years to prevent failure.
Conclusion & Next Steps
Your Hayward H150 pool heater is built for performance and reliability, but like any appliance, it requires maintenance and occasional repairs. Whether you’re dealing with ignition issues, flow errors, or overheating, most problems can be fixed with basic tools and a little know-how.
Start with the display panel and power, then check gas, flow, and sensors. Regular cleaning and seasonal checkups can prevent most costly issues before they begin.
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