Pentair pool heaters are known for their performance and reliability—but like any high-tech equipment, they can run into issues. Whether your heater won’t ignite, throws an error code, or shuts off unexpectedly, understanding the cause is key to a quick fix.
This guide walks you through the most common Pentair pool heater problems, what causes them, and how to troubleshoot each issue efficiently so your pool stays warm and ready to enjoy.
1. Pentair Heater Won’t Turn On
Quick Answer: If your Pentair pool heater isn’t turning on, it’s often due to a power issue, incorrect thermostat setting, or water flow restriction.
How to Troubleshoot:
- Check power supply: Ensure the heater is plugged in and the breaker is not tripped.
- Thermostat setting: Set the temperature at least 5 degrees higher than the current water temp.
- Inspect water flow: Dirty filters or low water pressure can prevent the heater from engaging.
Recommended Product: Use a Pentair Flow Sensor Switch replacement if your existing switch fails to detect proper water movement.
2. Pentair Heater Not Igniting
Quick Answer: If the unit clicks or tries to start but never lights, the problem is usually a faulty igniter, gas supply issue, or pressure switch failure.
Fix Checklist:
- Check gas supply: Make sure valves are open and gas pressure is adequate.
- Inspect igniter: A cracked or worn igniter won’t spark. Replace it if it shows damage or wear.
- Test pressure switch: Use a multimeter to ensure continuity when the system is running.
Best Replacement: The Pentair MasterTemp Igniter Kit fits most Pentair models and restores quick ignition performance.
3. Heater Turns On Then Shuts Off
Quick Answer: A Pentair heater that starts then shuts off after a few seconds or minutes usually has a flow issue, high-limit sensor fault, or internal overheating.
What to Do:
- Clean the filter: Reduced flow can cause an automatic shut-off.
- Check high-limit switches: These cut off the heater if internal temperature is too high—replace if faulty.
- Look for scale buildup: Mineral scaling inside the heat exchanger causes localized overheating.
Pro Tip: Use ScaleTec Plus as a descaler to treat and prevent buildup inside the heater core.
4. Pentair Heater Error Codes Explained
Quick Answer: Most Pentair pool heaters will display an error code that points to the specific issue. Understanding the code saves hours of guesswork.
| Error Code | Meaning | Solution |
|---|---|---|
| ERR PS | Pressure switch open | Check water flow, clean filter, or replace switch |
| ERR HLS | High-limit switch triggered | Inspect heater for blockages or faulty sensor |
| ERR AGS | Auto gas shutoff triggered | Check igniter, flame sensor, or gas supply |
| ERR ROLLOUT | Flame rollout detected | Check for blockage or cracked heat exchanger |
Helpful Add-On: Install a Pentair Diagnostic Display Replacement Kit if your screen is dim or not readable—it helps decode and fix issues faster.
5. Heater Making Loud or Popping Noises
Quick Answer: Noises are typically caused by scale buildup in the heat exchanger or poor water chemistry causing hot spots.
Solutions:
- Flush the system: Use a descaling solution through the heater annually.
- Balance pool water: Maintain calcium hardness between 200–400 ppm to prevent corrosion or scaling.
Descaling Solution: Use ProTeam Metal Magic to eliminate scale and protect internal heater parts.
6. Pentair Heater Display Not Working
Quick Answer: A dead or unresponsive display is often caused by power board failure, corrosion, or internal moisture.
What to Check:
- Ensure power is reaching the control board
- Open the control panel and inspect for corrosion or loose wiring
- Use a multimeter to check for voltage at the board terminals
Replacement Option: Swap in a Pentair Heater Control Board Assembly to restore full digital functionality.
7. Heater Is Heating Slowly or Not Reaching Set Temperature
Quick Answer: Poor heating can be due to low BTU rating for your pool size, dirty heat exchanger, or a failing temperature sensor.
Fix It Fast:
- Clean the heater’s interior with compressed air and a soft brush
- Ensure water chemistry is balanced—especially pH and alkalinity
- Replace the water temperature sensor if readings are off
Upgrade Tip: If your current heater struggles to keep up, consider upgrading to the Pentair MasterTemp 400—ideal for larger or heavily used pools.
Maintenance Tips to Prevent Pentair Heater Problems
Monthly:
- Inspect water chemistry—especially calcium hardness and pH
- Check for visible leaks, rust, or signs of wear
Quarterly:
- Flush the heat exchanger using a non-corrosive descaler
- Vacuum around the heater to remove debris or rodent nests
Annually:
- Have a technician inspect gas lines, igniter, and burner
- Replace worn seals and gaskets if corrosion is visible
Maintenance Kit Suggestion: Use the Pentair Annual Service Kit with gaskets, sensor caps, and sealant for easy upkeep.
When to Replace Your Pentair Pool Heater
If your heater is 8–12 years old and experiencing repeated breakdowns, replacement may be more cost-effective than continued repairs.
Signs It’s Time to Replace:
- Multiple error codes despite part replacements
- Increased heating time and energy bills
- Cracked heat exchanger or severe corrosion
Top Replacement Choice: The Pentair MasterTemp 400 High-Performance Heater offers fast heating, quiet operation, and energy efficiency—perfect for replacing outdated units.
Conclusion: Get Your Pentair Heater Back on Track
Pentair pool heaters are built for durability, but regular maintenance and fast troubleshooting are key to long-term performance. From ignition failures and error codes to display issues and heating delays, most problems are manageable with the right knowledge and tools.
Need parts or an upgrade? Start with one of the trusted Pentair-compatible components above to fix common heater issues and get your pool warm and swim-ready in no time.