Raypak Pool Heater Error Codes Explained
Complete Guide to PRS, SNS, HL1, HL2, IGN, ROL, BD1 and What to Check First
Raypak pool heater error codes can be helpful, but they can also be confusing. One heater may show a short code like PRS, SNS, HL1, HL2, IGN, ROL, or BD1. Another Raypak digital heater may show a longer message like Water Sw Open, Sensor Failure, Hi Limit 1 Fault, Hi Limit 2 Fault, Rollout Sw Open, Ignition Lockout, or Ignition Failure.
The exact wording depends on the heater model, control system, and display style. That is why the safest first step is always to confirm your exact Raypak model number and compare the code against the correct manual for your unit.
This guide explains what the most common Raypak heater codes usually point to, what to check first, and which types of parts may be involved. It is not meant to replace a qualified pool heater technician. Gas pool heaters include gas, ignition, electrical, water-flow, and safety-control components. If you smell gas, see burned wiring, have repeated rollout issues, or are not comfortable working around the equipment, stop and call a qualified professional.
Quick reference guide to all common Raypak heater error codes and initial troubleshooting steps
Before You Troubleshoot a Raypak Gas Pool Heater
A Raypak heater error code is not just a random warning. It usually means the heater has stopped because one of its safety or operating circuits is not satisfied. That can involve water pressure, water flow, high-limit protection, temperature sensing, ignition, rollout protection, or the control board.
Critical Safety Rules:
- Do not bypass safety switches
- Do not keep resetting the heater without finding the cause
- Do not assume every code means one guaranteed bad part
- A code tells you where the heater is seeing a problem, but the cause may be somewhere else in the pool system
For example, a pressure-switch code may be caused by a bad pressure switch, but it may also be caused by a dirty filter, low water level, closed valve, weak pump flow, clogged basket, or air in the system. Replacing the switch without fixing the water-flow problem will not solve the real issue.
Six essential checks homeowners can safely perform before calling a technician
Anything involving gas pressure, burner trays, ignition parts, internal wiring, rollout switches, heat exchangers, or control-board diagnosis should be handled carefully and, in many cases, by a qualified technician.
Raypak Error Codes Are Usually Safety Circuit Warnings
A pool heater depends on more than the heater cabinet itself. It needs enough water flow, clean filtration, proper gas supply, correct ignition, safe exhaust, accurate sensors, and working safety switches.
That is why a Raypak heater code should be read as a clue, not a final diagnosis. The heater may be protecting itself from low flow, overheating, ignition failure, flame rollout, sensor problems, or a control-board fault.
If your Raypak heater is showing a code, write down the exact message before turning anything off. Also note when the code appears. Does it show immediately when power is turned on? Only when there is a call for heat? After the heater fires for a few minutes? After the pump changes speed? Those details matter.
Quick Raypak Heater Error Code Table
| Code or Display | What It Points To | First Things to Check | Parts Commonly Involved |
|---|---|---|---|
| PRS or Water Sw Open | Water pressure switch open, often related to flow | Pump, water level, filter pressure, baskets, valves, flow through heater | Pressure switch, filter parts, pump parts, valves |
| SNS, Sensor Failure, Sensor Open, or Sensor Short | Temperature sensor or thermistor issue | Displayed temperature, sensor wiring, connector, sensor seating, resistance test | Temperature sensor, thermistor, control board if sensor checks good |
| HL1 or Hi Limit 1 Fault | High limit 1 open | Water flow, dirty filter, overheating, internal bypass, Unitherm governor | High limit switch, bypass parts, Unitherm governor, filter parts |
| HL2 or Hi Limit 2 Fault | High limit 2 open | Water flow, internal restriction, overheating, bypass issue | High limit switch, bypass parts, Unitherm governor |
| IGN, Ignition Lockout, or Ignition Failure | Ignition or flame proving issue | Call for heat, gas supply, pilot, spark, ignition wiring, flame sensing | Pilot assembly, ignition wire, gas valve, control board |
| ROL or Rollout Sw Open | Rollout switch open or rollout protection triggered | Stop use, check for blocked heat exchanger, soot, flame rollout, venting, combustion issues | Rollout switch, fusible link, refractory parts, heat exchanger service |
| BD1 or Internal Fault | Board fault or internal control issue, depending on model/source | Confirm manual, power supply, wiring, and model-specific guidance | Control board |
| EEP or EEPROM Fault | Memory fault | Reset setpoints if directed, see if fault clears | Control board if fault returns |
| CFH | Call for heat | Normal operating status on some models | Usually not a part failure by itself |
| Spark | Spark operating | Normal ignition status on some models | Usually not a part failure by itself |
PRS or Water Sw Open: Water Pressure Switch Open
A PRS code or Water Sw Open message points to the water pressure switch circuit. On Raypak digital heaters, Water Sw Open means the water pressure switch is open. In plain English, the heater does not see the water pressure condition it needs to safely fire.
This does not always mean the pressure switch itself is bad. The heater may not be getting enough water flow. Since the heater relies on water moving through the heat exchanger, low flow can prevent the heater from firing or cause it to shut down.
Check these items first:
- Is the pool pump running?
- Is the pump fully primed?
- Is the pool water level high enough?
- Are the skimmer and pump baskets clean?
- Is the filter dirty or overdue for cleaning?
- Is the filter pressure higher or lower than normal?
- Are all suction and return valves open?
- Is there strong flow returning to the pool?
- Was the heater installed above or below the pool water level in a way that affects pressure switch adjustment?
If the pump is running correctly, the filter is clean, valves are open, and water flow is strong, then the pressure switch and its wiring become more likely suspects. The Raypak H000025 Water Pressure Switch Kit is one replacement option for compatible Raypak pool heaters, but compatibility should always be confirmed by model number before ordering.
SNS, Sensor Failure, Sensor Open, or Sensor Short
SNS and sensor-related messages point toward the heater's temperature-sensing circuit. Depending on the heater and display, the message may appear as SNS, Sensor Failure, Sensor Open, or Sensor Short.
Raypak digital manuals describe sensor messages in terms of thermistor readings. A sensor failure can happen when thermistor readings disagree. A sensor open condition can indicate a failed-open sensor. A sensor short condition can indicate a failed-short sensor.
Start with the basics:
- Is the temperature shown on the heater believable?
- Does the heater show an impossible or obviously incorrect temperature?
- Is the sensor fully seated in the proper location?
- Are the sensor wires damaged, loose, pinched, or corroded?
- Is the connector clean and secure?
- Has the sensor been tested against the correct resistance chart for the heater?
A bad temperature sensor can make a heater cycle incorrectly, shut down, or display the wrong water temperature. If the sensor tests outside the correct range, replacement may be needed. If the sensor and wiring test correctly but the fault remains, the control board may need further diagnosis.
Common Raypak temperature sensor options include the Raypak 005299B Temperature Sensor for IID Pool Heaters, Raypak 006701F Temperature Sensor Kit, and Raypak 009577F Temperature Sensor Replacement. Match the part to your exact heater model before ordering.
HL1 and HL2: High Limit Faults
HL1 and HL2 point to high-limit protection. On Raypak digital heaters, Hi Limit 1 Fault means high limit 1 is open. Hi Limit 2 Fault means high limit 2 is open.
High limits are safety devices. They are there to stop operation when the heater sees an over-temperature condition. A high-limit fault can be caused by a bad high-limit switch, but it can also be caused by the heater getting too hot because water is not moving through it correctly.
Before replacing a high-limit switch, check for water-flow and internal restriction issues:
- Dirty filter
- Low pump speed or weak flow
- Closed or partially closed valves
- Air in the system
- Scale buildup inside the heater
- Internal bypass problem
- Unitherm governor issue
- Heat exchanger restriction
This is where many heater problems get misdiagnosed. If the heater overheats because of poor water flow, replacing a high-limit part alone may not fix the root cause. The water-flow problem still has to be corrected.
The internal bypass and Unitherm governor are especially important because they help control how water moves through the heater. If a bypass part sticks, wears out, or fails, the heater may experience unstable heating, short cycling, or safety trips.
If your heater uses a compatible bypass kit, the Raypak 011601F Bypass Kit may be relevant. Always confirm compatibility with the heater model and parts breakdown before ordering.
IGN, Ignition Lockout, or Ignition Failure
IGN, Ignition Lockout, and Ignition Failure messages point to an ignition or flame-proving issue. This means the heater tried to start but did not complete the ignition sequence correctly, or it lost pilot or flame confirmation during the process.
This is one of the sections where safety matters most. Ignition problems can involve gas supply, pilot flame, spark, ignition wiring, flame sensing, gas valve operation, or control-board output. Those are not areas where guessing is a good idea.
Basic checks include:
- Is the heater powered on?
- Is there a call for heat?
- Is the thermostat set above the current water temperature?
- Is the gas supply on?
- Has the heater recently been serviced, winterized, or reconnected?
- Does the code appear immediately, or only after the heater tries to ignite?
Technician-level checks may include pilot assembly condition, spark, pilot orifice, ignition wire, flame sensing, gas valve operation, gas pressure, and board output. If you smell gas, stop immediately and follow proper gas-safety procedures.
Parts commonly involved in ignition-related Raypak repairs can include pilot assemblies, pilot tubes, ignition wires, gas valves, and control boards. Aqua Terra Backyard carries Raypak-related heater parts such as the Raypak pilot tube and IID pilot assembly through compatible heater parts collections.
ROL or Rollout Sw Open
Possible areas a qualified technician may inspect include:
- Blocked heat exchanger
- Soot buildup
- Flame rollout evidence
- Burned wiring
- Refractory condition
- Burner condition
- Venting or downdraft issues
- Combustion air problems
Depending on the model and the damage found, parts such as rollout switches, fusible links, refractory parts, or heat exchanger components may be involved. For compatible models, Aqua Terra Backyard carries Raypak heater components such as the Raypak 010088F Atmospheric Refractory Set, Raypak 006735F Tube Bundle, and Raypak 004674F Heat-Only Exchanger.
BD1, Internal Fault, EEP, and EEPROM Fault
BD1, Internal Fault, EEP, and EEPROM Fault messages point more toward the heater's control logic or control board, depending on the exact heater and code source.
On Raypak digital heaters, an Internal Fault is identified as a board fault. An EEPROM Fault is a memory fault. Some shortened Raypak fault-code guides also list BD1 as a board failure and EEP as a memory-related fault.
Before ordering a control board, confirm:
- The exact heater model number
- The serial number
- The exact displayed code
- Whether the code appears immediately at power-up
- Whether the code returns after a proper reset
- Whether supply voltage and wiring have been checked
- Whether the board part number matches your heater
Control boards are model-specific and should not be guessed by appearance alone. If you need help matching a Raypak board, take a clear photo of the heater data plate, the existing board, and the displayed code before contacting us.
Normal Raypak Display Messages That Are Not Always Faults
Not every message on a Raypak heater display is an error code. Some messages are normal operating statuses.
CFH
CFH usually means call for heat. It means the heater is being asked to heat the pool or spa. By itself, it is not automatically a failure code.
Spark
Spark can appear during the ignition sequence. By itself, it can be a normal ignition status message. If the heater stays in spark, fails to light, or moves into ignition failure, then further diagnosis is needed.
No Demand
No Demand means the heater is not currently being asked to heat, usually because the set temperature has been satisfied or there is no active call for heat.
Heating
Heating means the heater has established heat operation and flame is present on models that display this status.
What to Check Before Ordering Raypak Heater Parts
Raypak heaters have many model variations. Before ordering replacement parts, collect the right information so you do not end up with an incompatible part.
Before ordering, confirm:
- Full heater model number
- Serial number
- Gas type, natural gas or propane
- Digital or millivolt ignition style
- ASME or non-ASME model
- Elevation or altitude version, if applicable
- Exact displayed error code or message
- When the code appears
- Current filter pressure
- Whether the pump and filter are operating normally
- Clear photos of the existing part and heater data plate
This is especially important for pressure switches, sensors, high limits, gas parts, control boards, bypass parts, and heat exchanger components. Many parts look similar but are not interchangeable.
If you are unsure, contact Aqua Terra Backyard with your model number, serial number, gas type, and photos. We can help point you toward the right Raypak replacement part when the information is clear.
When to Repair the Heater vs Replace It
A Raypak heater code does not automatically mean the whole heater is done. Many problems can be repaired when the heater body is in good condition and the failed part is still available.
✓ Repair May Make Sense When:
- Pressure switch or water-flow safety circuit
- Temperature sensor or thermistor
- High-limit switch
- Internal bypass or Unitherm governor
- Pilot assembly or ignition component
- Header gasket or serviceable water-side part
- Control board on an otherwise healthy heater
✗ Replacement May Make More Sense When:
- A leaking or badly scaled heat exchanger
- Severe corrosion
- Freeze damage
- Multiple expensive failures at the same time
- Recurring safety trips after proper service
- Wrong gas type for the installation
- Wrong elevation version for the location
- Discontinued or hard-to-source major parts
If the repair is small and the heater is otherwise solid, replacing the part may be the best move. If the heat exchanger, combustion system, or multiple major controls are failing, it may be smarter to compare repair cost against a new heater.
Frequently Asked Questions About Raypak Heater Error Codes
What does PRS mean on a Raypak pool heater?
PRS usually points to a low water pressure or water pressure switch issue. On some Raypak digital heaters, the longer display message may be Water Sw Open, which means the water pressure switch is open. Check pump operation, water level, baskets, filter pressure, valves, and flow before assuming the pressure switch is bad.
What does Water Sw Open mean on a Raypak heater?
Water Sw Open means the water pressure switch is open. The heater is not seeing the water pressure condition it needs to fire safely. This can be caused by poor water flow, a dirty filter, a pump problem, closed valves, low water level, air in the system, or a pressure switch issue.
What does SNS mean on a Raypak heater?
SNS usually points to a temperature sensor or thermistor problem. Depending on the model, the heater may display Sensor Failure, Sensor Open, Sensor Short, or a shortened SNS code. Check the displayed temperature, sensor seating, wiring, connector condition, and sensor resistance before replacing parts.
What causes HL1 or HL2 on a Raypak heater?
HL1 and HL2 are high-limit faults. They can be caused by high-limit switch issues, but they can also be caused by overheating from low water flow, a dirty filter, closed valves, scale buildup, a stuck internal bypass, or a Unitherm governor problem.
Why does my Raypak heater say IGN or Ignition Failure?
IGN or Ignition Failure means the heater did not complete ignition or did not prove flame correctly. Possible causes include gas supply problems, pilot issues, spark problems, ignition wiring, flame sensing, gas valve operation, or control-board output. Gas and ignition diagnosis should be handled carefully by a qualified technician.
Is CFH an error code on a Raypak heater?
CFH usually means call for heat. It is not automatically an error code. It means the heater is being asked to heat. If the heater remains in call for heat but never fires, then you need to look at the next status message or fault code.
Can a dirty filter cause Raypak heater error codes?
Yes. A dirty filter can restrict water flow through the heater. That can contribute to Water Sw Open, PRS, high-limit faults, short cycling, or shutdowns. Always check filter pressure and clean or backwash the filter before assuming the heater part itself has failed.
Can low water flow cause a Raypak heater to shut down?
Yes. Low water flow can prevent the heater from firing or cause it to shut down for safety. The heater needs enough water moving through the heat exchanger to operate properly.
Should I replace the pressure switch if I get a PRS code?
Not immediately. A pressure switch can fail, but PRS often points to a water-flow issue first. Check pump operation, water level, baskets, filter pressure, valves, and heater flow before replacing the pressure switch.
What information do I need before ordering Raypak heater parts?
You should confirm the heater model number, serial number, gas type, exact code, and part number if possible. Clear photos of the heater data plate and existing part are also helpful. This matters because many Raypak heater parts look similar but are not interchangeable.