This guide decodes the fault codes on Raypak pool heaters — the 3-letter codes on Digital 206A–406A models, the full-word messages on 106A/156A and Avia units — with the safe checks a homeowner can do first. We're the Pinellas County company licensed for the gas and electrical side of these repairs (LI4527, EC13011994, CPC1459998).
First: Which Raypak Code Family Do You Have?
Raypak has used three different display systems, and the codes differ by family. The Digital series (206A / 266A / 336A / 406A) shows a 2-digit LED with 3-letter fault codes and a flashing "SERVICE" indicator. The 106A / 156A atmospheric heaters use an LCD with full-word messages like "Water Sw Open" or "Ignition Lockout." The current Avia line (264A / 404A) has a backlit LCD that also spells out its faults in plain words. Find your family below, then jump to your code.
Digital Series (206A–406A) 3-Letter Codes
PRS — Water Pressure Switch Open
The heater isn't seeing enough water pressure or flow, so it refuses to fire — per Raypak's 206A service documentation, this is the pressure switch reporting "PS open." The most likely causes are the pump being off or running at a low speed, a dirty filter or full baskets, low pool water level, or valves diverting water around the heater.
- Confirm the filter pump is running — on high speed if it's a variable-speed pump.
- Empty the skimmer and pump baskets; clean or backwash the filter.
- Top the pool water up to mid-skimmer.
- Verify the valves are actually sending water through the heater.
HL1 / HL2 — High-Limit Switch Tripped
One of the two high-limit switches opened because water inside the heat exchanger exceeded roughly 135°F. That almost always means restricted water flow — a dirty filter, full baskets, or closed-down valves — or a scaled heat exchanger that can't shed heat into the water.
- Do the same flow checks as PRS: clean baskets, clean the filter, open the valves, run the pump on high.
- Once flow is restored, power-cycle the heater once at the breaker.
SNS — Temperature Sensor Out of Range
The heater's temperature sensor is reading below 36°F or above 110°F, or its thermistors disagree with each other. The usual culprits are a failed thermistor or corroded, loose sensor wiring — corrosion moves fast in coastal Florida's salt air.
- Power-cycle the heater once at the breaker.
- Note whether the displayed water temperature is obviously wrong — that detail helps the technician.
IGN — Ignition Failure
The heater tried to light three times and never proved a flame. (IGN appearing briefly during startup is the normal light-off sequence, not a fault.) Common causes are air in the gas line or the gas shut off, low inlet gas pressure from an undersized line or a low propane tank, a dirty igniter or corroded flame rod, or condensate dripping on the burner.
- Confirm the gas supply valve to the heater is on.
- On propane, check that the tank is above roughly 30%.
- Power-cycle the heater once.
Raypak Heater Repair Across Pinellas
Raypak heater repair in Largo, St. Pete, Clearwater & all of Pinellas — we service the gas, electrical, and pool sides under our own licenses (LI4527 · EC13011994 · CPC1459998). Priority dispatch: 727-788-4086.
Pool Heater Repair See all service areas →ILO — Ignition Lockout
After repeated failed ignition attempts, the heater has stopped trying to light — Raypak flags this lockout especially on propane units. The causes are the same as IGN, now persistent: a real gas-supply problem, a failing pilot or igniter assembly, or a control board fault.
- Reset at the breaker one time only.
- If it locks out again, leave it off.
ROL — Flame Rollout Switch Open
Treat ROL as a stop-now code. The rollout safety switch or thermal fuse opened because flame left the combustion chamber — typically from wind or downdraft blowing flame out of the burner tray, or a soot- or scale-blocked heat exchanger forcing it out. There is no homeowner fix beyond noting whether the heater sits in a wind-exposed spot.
- Leave the heater off. Do not reset it repeatedly.
- Note any wind exposure at the heater's location for the service call.
FAN — Combustion Air Switch Didn't Close
On fan-assisted models, the blower's air-pressure switch never closed — the heater can't confirm combustion air is moving. Likely causes are a blocked vent or flue (nests and debris are common), a failed blower motor, or clogged pressure-tap tubing.
- From the ground, look at the vent top for obvious blockage. Don't climb or reach into the flue.
GVC / GVO — Gas Valve Fault
The gas valve isn't doing what the board commanded: GVC means no voltage at the valve when it should be on; GVO means voltage is present when it should be off. That points to a board fault, a wiring or connection problem, a weak transformer, or a failed gas valve itself.
- Power-cycle the heater once at the breaker.
FFL — Flame Sensed With Gas Valves Closed
Treat FFL as an urgent stop-now code. The heater is sensing flame while both gas valves are commanded shut — which means gas may be leaking through a closed valve, or the flame-sense circuit has failed. Either way, this unit should not keep running.
- Shut the heater off and stop using it.
VNT — Vent Switch Open
The vent switch circuit is open. On outdoor heaters this circuit is factory-jumped, so VNT usually means a tripped vent spill switch on an indoor install or a jumper/wiring fault. There are no safe homeowner steps for this one.
BD1 / EEP — Control Board or Memory Fault
The control board has failed its self-check (BD1) or its memory is corrupted (EEP) — often the aftermath of a power surge or brown-out, both routine events in a Florida lightning season. One clean power cycle sometimes recovers it.
- Turn the heater off at the breaker, wait 30 seconds, and restore power once.
- If the code returns, you're done — leave it off.
Raypak 106A / 156A Full-Word Messages
The 106A/156A LCD spells out its faults, and per Raypak's manual for these models they map to the same problems covered above. "Water Sw Open" is the pressure switch — see PRS. "Hi Limit 1/2 Fault" — see HL1/HL2. "Rollout Sw Open" — see ROL, and treat it as stop-now. "Ignition Lockout" (alternating with "No pilot sensed" or "Main Ign Failure") and "Ignition Failure" — see IGN and ILO; on non-propane units, "Ign 6min Delay" means the heater lost the pilot four times and is waiting six minutes before retrying. "Sensor Failure / Open / Short" — see SNS. "Flame w/o CFH" — see FFL, an urgent stop. "PV/MV Output Fault" is the gas-valve fault — see GVC/GVO. "Internal Fault" and "EEPROM Fault" — see BD1/EEP. "Clock/Fireman Sw" means an external interlock circuit is open, and "Low Temp Lockout" means the water is below 36°F. The safe homeowner checks and the stop points are the same as the matching codes above.
Raypak Avia Fault Messages
First, know the Avia's normal status messages: "No Demand," "Pre-Purge," "Spark," "Heating," and "Post-Purge" are the ordinary operating sequence, not faults.
For actual faults, the Avia manual gives the homeowner three legitimate moves: the flow checks (clean filter, empty baskets, correct valve positions, pump on high), one power cycle, and pressing the MODE key to clear a fault where the display instructs — for example after fixing flow on a "Hi Limit 1/2 Fault." "Water Sw Open" is the flow fault; "Low Flow Fault" warns of low flow through the heater (possible scaling) and "High Flow Fault" of too much flow (possible condensation). Ignition faults escalate from "Ign Try Failure" to "Ignition Lockout" — and "Ign 60 min Delay" means the gas valve failed three times in one call for heat, so the heater is locked out for an hour. "Gas Valve Fault" (valve sensed on when commanded off) and "Flame w/o CFH" are urgent — stop using the heater. The flue family — "Flue Sensor Open/Shrt," "Flue Over Temp," "Flue Low Temp," and especially "Flue Extreme Low" — plus "Air SW Open," "Diff Sw" faults and "Fan Lockout" are all combustion-air and venting issues: licensed-gas territory. "Call Service" means one of the serious lockouts happened three times in 48 hours — the heater itself is telling you to stop resetting it.
Seeing an E-Code (E01, E05, E06)?
Some older or regional Raypak displays show E-codes instead of the codes above. Field guides map E01 to ignition failure/lockout (see IGN/ILO), E05 to flame loss, and E06 to a faulty high-limit switch (see HL1/HL2) — but these don't appear in Raypak's current 106A/156A or Avia manuals, so confirm the meaning against your own model's manual before acting on it. Whatever the display style, the safe steps are the same: flow checks, one power cycle, then call.
Why Homeowners Across Pinellas Call Us for Raypak Heaters
- Licensed for the gas side (LI4527): ignition failures, lockouts, gas-valve faults, and venting problems are the bulk of Raypak codes — and every one of them is legally and practically licensed-gas work.
- Licensed for the electrical side (EC13011994): sensor faults, board failures after lightning-season surges, and wiring corroded by salt air get diagnosed and repaired on the same visit, no second contractor.
- Licensed pool contractor (CPC1459998): most heater codes start as flow problems — filters, valves, pumps — and we service that whole system, not just the heater box.