Raypak pool and spa heaters are known for their durability and ease of operation. Whether you have a gas-fired model or one of the newer digital versions, a properly working heater makes a big difference in extending your swim season. But when your Raypak heater refuses to fire, shuts down unexpectedly, or doesn’t heat properly, you’ll need a clear plan to find the cause.
This guide walks through the most common Raypak heater problems, why they happen, and how to fix them. We’ll also include maintenance tips to prevent issues from coming back.
How Raypak Heaters Work
Raypak heaters use gas (natural or propane) to heat water that is pumped through a copper or cupronickel heat exchanger. A thermostat or control board senses the water temperature and turns the burner on and off to maintain your set temperature. Safety switches and sensors monitor water flow, temperature, and combustion, shutting the unit down if conditions aren’t safe.
Most troubleshooting comes down to three main categories: ignition problems, heating performance issues, and sensor/safety shutdowns.
Common Raypak Heater Problems and Fixes
1. Heater Won’t Ignite
Symptoms: You turn on the heater, but it never fires. Fans or blowers may run, but there’s no flame.
Possible causes:
- No gas supply or closed gas valve
- Low gas pressure
- Igniter failure
- Flame sensor not detecting flame
- Faulty control board
What to do:
- Check that the gas supply valve is fully open.
- Confirm propane tank level or natural gas supply.
- Inspect ignition components for wear or cracks; replace if faulty.
- Clean the flame sensor gently with fine steel wool to remove buildup.
- If ignition still fails, have a qualified technician check gas pressure and board operation.
2. Heater Starts, Then Shuts Off
Symptoms: Heater lights, runs briefly, then turns off before reaching set temperature.
Possible causes:
- Water flow issue triggering pressure switch
- High-limit switch shutting heater down
- Flame signal lost during operation
What to do:
- Clean or backwash filter to improve water flow.
- Ensure pump is running at proper speed.
- Inspect high-limit sensors for corrosion or damage; replace if faulty.
- Check for venting or draft problems causing flame instability.
3. Heater Heats Slowly or Not Enough
Symptoms: Heater runs but takes a long time to raise water temperature.
Possible causes:
- Scale buildup in heat exchanger reducing efficiency
- Low gas pressure
- Cold ambient temperatures affecting performance
- Thermostat set too low or miscalibrated
What to do:
- Check thermostat setting on control panel.
- Inspect heat exchanger for signs of scale or corrosion; descale if necessary.
- Verify gas supply and pressure with a technician.
- Consider using a solar cover to reduce heat loss from the pool.
4. Digital Display Error Codes
Modern Raypak heaters display error codes when they detect problems. Common codes include:
- PRS – Pressure switch open; check pump and water flow.
- HLS – High-limit switch open; could be overheating or faulty sensor.
- FLO – Low or no water flow; clean filter, check pump.
- SFS – Stack flue sensor fault; inspect venting and sensor connection.
- ROL – Rollout switch open; check for blocked or improper combustion.
What to do: Always address the root cause before resetting. Repeated tripping of safety devices means something in the system needs repair.
5. Unusual Noises During Operation
Symptoms: Popping, banging, or whistling sounds from the heater.
Possible causes:
- Scale buildup causing water to boil inside heat exchanger
- Debris in burners
- Air in gas line
What to do:
- Have heat exchanger inspected and cleaned.
- Clean burners to ensure proper flame pattern.
- Have gas line purged by a qualified professional.
6. Soot on Heater or Vent
Symptoms: Black soot marks on heater housing or vent outlet.
Possible causes:
- Incomplete combustion due to dirty burners
- Blocked flue or vent
- Improper gas/air mix
What to do:
- Shut down heater immediately.
- Inspect and clean burners.
- Clear vent of obstructions.
- Have a technician adjust gas/air mixture.
Basic Maintenance to Prevent Problems
- Keep pool water balanced—unbalanced water can corrode or scale the heat exchanger.
- Clean or backwash filter regularly to maintain proper flow.
- Inspect heater venting annually for obstructions or corrosion.
- Flush heat exchanger yearly in high-scale areas.
- Protect heater from flooding and excessive moisture.
When to Call a Professional
Some tasks—like replacing sensors, cleaning burners, or checking gas pressure—are best left to trained technicians. Call for service if:
- You smell gas near the heater.
- Error codes persist after basic fixes.
- You see water leaking from inside the heater housing.
- There’s visible corrosion or burn marks inside the unit.
Quick Recap
- No ignition: Check gas supply, igniter, flame sensor.
- Short cycling: Check water flow, high-limit switch, flame signal.
- Slow heating: Descale heat exchanger, check gas pressure, use solar cover.
- Error codes: Address root cause, don’t just reset.
- Noises: Remove scale, clean burners, purge air from gas line.
- Soot: Clean burners, check venting, adjust combustion.
Raypak heaters are reliable, but like any piece of pool equipment, they require occasional attention. By learning what the warning signs mean and performing regular maintenance, you can avoid costly repairs and keep your water warm all season.