7 Pool Heater Repair Problems and How to Troubleshoot Each One

You check the swimming pool before a weekend gathering and find the water is ice cold. The display shows the unit is running, but nothing happens. Your guests arrive in a few hours. Now what?

Problems with pool heating rarely announce themselves in advance. One day, everything functions fine. The next day, you’re staring at cold water, wondering what went wrong.

In Long Beach and surrounding coastal areas, heating systems run more months per year than in seasonal climates. That extra use affects wear patterns, making understanding these problems even more useful.

Need immediate help? Our Long Beach repair and installation team responds within 24 hours.

If your unit stops working, start with these basic checks before calling for a service call:

1. Verify the thermostat is set higher than the current temperature
2. Check the pilot light (gas units) or confirm power at the breaker (electric models)
3. Look for error codes on the digital display
4. Inspect the supply valve to ensure it’s fully open
5. Clean or backwash your filter (restricted flow triggers safety shutoffs)
6. Check the pressure switch and flow sensor for debris
7. Reset the unit by turning it off for 30 seconds, then back on

If these steps don’t restore heat, the problem likely requires expert diagnosis. Issues with valves, heat exchangers, or control boards need a trained specialist with proper pool equipment.

Problem 1: Unit Won’t Ignite

A unit that won’t ignite is the most common service request we receive. In our 15 years of serving Long Beach property owners, ignition problems are consistently the top reason customers call for help.

What causes ignition failure?

Older gas pool heaters use a standing pilot light that can blow out or become clogged with debris. If your pilot won’t stay lit, the thermocouple may need replacement.

Modern units use electronic ignition. These are more reliable but have more components that can fail. The igniter itself can wear out, or the flame sensor can become coated with residue and fail to detect the flame.

Supply problems also prevent ignition. Check that the valve is fully open. If other appliances work but your unit won’t light, the problem is likely the valve or orifices.

When to call a professional:

If you’ve confirmed supply is present and the igniter glows but the unit still won’t light, the problem is usually the ignition module or valve. Both require a licensed contractor with gas line expertise. Our technicians handle electrical, plumbing, and gas components, so we diagnose the complete system rather than just one part.

Long Beach’s coastal salt air accelerates corrosion on ignition components. In our experience, units near the beach often need igniter and sensor replacement sooner than inland installations.

Problem 2: Heater Runs But Won’t Warm the Pool

Your unit fires up and runs through its cycle, but the pool stays cold. This frustrating problem usually points to heat transfer issues, and it’s something we see frequently in Long Beach pools with hard water.

Common causes:

Scale buildup inside the exchanger is the primary culprit. Hard deposits create an insulating layer that prevents warmth from reaching the pool. In our experience, even moderate scale buildup forces the unit to run significantly longer to achieve the same results, driving up energy costs.

Bypass valve misadjustment is another cause. If too much bypasses the unit, not enough passes through to absorb warmth properly.

Insufficient pressure prevents the burner from producing enough output. This can happen when multiple appliances run simultaneously or when the meter can’t deliver adequate volume.

Finally, undersized units struggle to raise temperatures in larger pools, especially during winter or when the pool has been unused for extended periods. When we assess a pool heating system, we calculate whether the unit matches the pool’s actual size and usage patterns.

What you can check:

Verify your pool pump is operating at normal speed, and the flow is moving through the unit. Listen for the burner firing and observe the exhaust. If the unit functions but doesn’t warm anything, scale buildup or size issues are likely.

Problem 3: Unit Cycles On and Off Repeatedly

Short-cycling means your unit starts, operates briefly, shuts off, and then repeats. This pattern prevents proper pool heating and stresses components.

Why units short-cycle:

The pressure switch monitors flow through the unit. When the flow drops below safe levels, the switch shuts off the unit to prevent damage. A dirty pool is the most common cause. Before assuming the unit is broken, backwash your filtration.

The high-limit switch protects against overheating. If this switch trips repeatedly, the unit may have inadequate flow, a failing pump, or blocked return lines.

Thermostat problems can also cause cycling. A miscalibrated thermostat may think conditions are different than actual readings, triggering premature shutoff.

Practical tip from our experience:

When customers contact us about short-cycling, we ask them to address filtration first. In many cases, that solves the problem without a visit. It’s the best approach and costs nothing to try. This is part of our “Pool School” philosophy: we’d rather teach you to spot simple fixes than charge for unnecessary service calls.

Pressure fluctuations during high-demand periods can also cause cycling. If the problem only happens at certain times of day, supply may be the issue.

Problem 4: Error Codes on Digital Display

Modern units display error codes when something goes wrong. Understanding these codes helps you communicate with your specialist and sometimes reveals simple fixes.

Common Jandy error codes:

Common Pentair error codes:

Other brands like Hayward and Raypak have their own specific code systems. While we specialize in Jandy and Pentair systems, we can diagnose other major brands as well.

Important note: Error codes may vary by model and software version. Your owner’s manual contains codes specific to your unit. When in doubt, a certified technician can interpret codes for your exact equipment.

When error codes indicate simple fixes:

Pressure switch and high limit codes often clear after addressing filtration and verifying proper pump operation. Reset the unit after addressing the underlying cause.

When to seek help:

Ignition lockout, stack flue, and repeated limit switch errors typically require diagnosis. These codes may indicate failing components or supply problems that need proper testing equipment.

Adam’s Pool and Spa is Jandy Certified and Pentair Expert Certified. We can interpret any error code and have access to the manufacturer’s technical support when needed.

Problem 5: Strange Noises Coming From the Unit

Pool heating units make some operational sounds, but unusual noises often signal developing problems. Catching these early can prevent more expensive repairs down the road.

What do different noises mean?

• Rumbling or booming: Delayed ignition allows buildup before igniting. This can damage the exchanger over time. Scale buildup inside the exchanger also causes rumbling. In coastal Long Beach, we often find that hard water combined with salt air creates conditions where scale accumulates faster than in other areas.

• Whistling: Usually indicates valve problems or partially blocked burner orifices. Debris in the line or improper pressure can create this sound.

• Clicking: Some clicking during startup is normal as the igniter fires. Continuous clicking without ignition means the unit is trying repeatedly to light and failing.

• Grinding: The blower motor that draws combustion air may have worn bearings. This sound typically gets worse over time.

• Popping: Condensation hitting the hot exchanger causes popping during startup. Some popping is normal, but excessive popping may indicate ventilation problems.

When noises require attention:

Any new noise warrants investigation. Rumbling and booming in particular should be addressed promptly to prevent exchanger damage, which is expensive to address.

Problem 6: Unit Leaking

Moisture around your unit always needs investigation. Some leaks are minor while others signal the end of the unit’s useful life. We believe in giving you honest information so you can make the right decision, not pushing replacement when a simple repair will serve you for years.

Where leaks come from:

Header gaskets seal the connections between the exchanger and manifolds. These gaskets deteriorate over time and can be addressed affordably.

Exchanger cracks are more serious. The exchanger is the most expensive part of the unit. Cracks usually result from repeated thermal stress, corrosion, or improper chemistry. Depending on the unit’s age, a new pool heater may make more sense.

Condensation during startup is normal and not a true leak. You may see dripping that stops once the unit heats up.

The pressure relief valve releases moisture when internal pressure exceeds safe limits. Occasional discharge is normal. Continuous release indicates a problem with pressure or the valve itself.

Coastal corrosion factor:

Long Beach’s proximity to the ocean means salt-laden air constantly contacts components. In our experience, beachside properties tend to see faster corrosion on exchangers due to salt air exposure. We’ve served this area long enough to recognize the patterns and can tell you honestly whether repair makes sense or if you’re better off replacing a corroded unit.

Leaks can create electrical hazards and cause further damage. If you notice moisture around your unit, our specialists can diagnose the source and recommend whether addressing it or replacement makes more sense.

Problem 7: Pool Heater Sensor Failures

Sensors monitor conditions throughout your unit. When sensors fail, the unit may not operate correctly or may shut down entirely. Because sensors connect to the automation and control board, diagnosing sensor problems often requires testing the entire system, not just the sensor itself.

Types of pool heaters and their sensors:

All major types, including electric heat pumps and combustion models, use sensors for monitoring. Understanding your specific setup helps with troubleshooting.

Temperature sensors tell the system when conditions reach the set point. A faulty sensor may cause the unit to overheat or never reach the desired warmth.

Pressure switch sensors confirm adequate flow before allowing ignition. Stuck or failing pressure switches cause nuisance shutdowns even when the flow is normal.

Flow sensors in some units measure actual volume passing through. Low readings trigger safety shutoffs.

High-limit sensors prevent dangerous overheating. These are safety devices that should rarely activate under normal conditions.

What sensor work typically costs:

Sensor replacements generally range from $150 to $400, including parts and labor, in our service area. However, actual costs depend on your specific unit, sensor type, and accessibility. The sensor itself may cost $30 to $100, but accessing it and calibrating the system requires specialized knowledge. We provide exact estimates after diagnosing your specific situation.

Signs of sensor problems:

Inconsistent readings, the unit shutting off before reaching the set point, or error codes specifically referencing sensors all suggest these components may need attention.

Does Your Unit Require Regular Maintenance?

Yes. Annual care extends lifespan and prevents many of the problems covered in this guide.

What maintenance includes:

• Inspect and address the burner assembly
• Checking all electrical connections for corrosion
• Testing pressure and combustion efficiency
• Examining the exchanger for scale and corrosion
• Verifying safety devices operate correctly
• Addressing the flame sensor and igniter

How maintenance prevents problems:

A trained specialist catches developing problems before they cause failures. Addressing the burner prevents ignition problems. Checking the exchanger reveals scale buildup, which is still manageable. Testing safety devices confirms they’ll protect your unit.

The cost comparison:

Annual maintenance typically costs far less than emergency repairs. The exact cost depends on your equipment and any issues discovered, but preventive care almost always saves money compared to waiting for failures. We provide estimates before any work begins.

Our “Pool School” approach means we spend 30 to 40 minutes explaining what we find and teaching you what to watch for between visits. We’d rather you understand your equipment and catch small problems early than keep you in the dark. That’s how we build relationships that last, and it’s why many of our customers have been with us for years.

When to Address Problems vs. Replace Your Unit

Not every problem warrants repair. Sometimes replacement makes more financial sense. We’ll give you an honest recommendation either way.

Typical lifespan:

According to the U.S. Department of Energy, pool heaters generally last several years to over a decade, depending on type, usage, and maintenance. In our experience serving Long Beach, gas units typically last 8 to 12 years with proper care, while heat pumps often reach 10 to 15 years. Coastal installations tend to fall toward the shorter end of these ranges due to salt air corrosion.

A common industry guideline:

Many contractors and consumer advocates suggest that if repairs cost more than 50% of a new unit’s price, replacement usually makes sense. This is especially true if your unit is approaching or past the 8-year mark.

When addressing the problem makes sense:

• Unit is less than 5 years old
• Problem is isolated (single sensor, gasket, igniter)
• The estimated repair cost is well below the replacement cost
• No other problems present

When replacement makes sense:

• The unit is over 10 years old
• Exchanger is cracked or severely corroded
• Multiple components are failing
• Repair estimate approaches 50% of the new unit price
• Energy efficiency improvements would pay back over time

Efficiency considerations:

Modern units with variable speed technology operate far more efficiently than older equipment. Based on our installations, customers with new variable speed components typically see operating cost reductions of 30 to 40% compared to older single-speed equipment. Over several years, these savings can offset a significant portion of replacement costs.

We’re Jandy Certified and Pentair Expert installers, which means your new equipment comes with extended warranties and faster warranty service.

Our philosophy is “from service to construction and everything in between.” Whether you need a simple repair or a complete equipment upgrade, we handle it all so you’re not juggling multiple contractors.

Not sure whether addressing the problem makes sense? Our team provides honest assessments and a free pool evaluation. We provide detailed estimates before any work begins and won’t push for replacement if a simpler solution will serve you well for years. Contact us at (562) 522-2203 for an estimate.

Key Takeaways

Problems range from simple filtration concerns to complex component failures. Starting with basic troubleshooting saves time and sometimes money. When problems exceed basic fixes, professional diagnosis prevents guesswork and unnecessary spending.

Regular care catches concerns early and extends your unit’s life. Understanding your equipment and having a reliable partner means fewer surprises and more time enjoying your pool.

Questions? Adam’s Pool and Spa has served Long Beach and the surrounding areas for 15 years. We’re Jandy Certified and Pentair Expert installers who provide straightforward answers about repair versus replacement.

Call our team at (562) 522-2203 or schedule a diagnostic online.