Raypak AVIA Diagnostic Guide
Want a guided diagnosis? Open the Raypak Heater Troubleshooter.
Raypak AVIA Diagnostic Guide
The AVIA control separates standing status messages from demand faults. Record the exact display text and the last entries in Fault History before resetting power. Press SERVICE once to view flame strength and service information; a flame signal below 1.0 microamp is weak and may require service.
Safety: Disconnect electrical power and follow the manual before opening equipment. Gas, combustion, line-voltage, pressurized-water, and refrigerant work belongs to qualified service personnel.
Status and sensor messages
| Display or symptom | What it means | Manual-backed check |
|---|---|---|
| No Communication With Ignition | The display is not communicating with the ignition control. | Check connector P7 and the communication harness. |
| In Sensor Fault | The inlet thermistors disagree by more than 3°F. | Check low-flow conditions, pump speed, inlet sensors, wiring, and placement. |
| In Sensor Open / In Sensor Short | The inlet reading is below 6°F or above 188°F. | Inspect inlet-sensor wires, harness terminals, and sensor resistance. |
| Out Sensor Open / Out Sensor Short | The outlet reading is below 6°F or above 188°F. | Inspect outlet-sensor wires, terminals, and sensor resistance. |
| Flue Sensor Open / Flue Sensor Short | The flue reading is above 464°F or below 7.5°F. | Inspect the flue sensor and its wiring before replacing parts. |
| Flow Sensor Fail | The flow sensor reading is outside the 0–100 GPM range. | Check the flow sensor, its setup, and wiring. |
| Pump Ctl Fail | The configured pump is not responding. | Confirm pump power, communication wiring, and pump-control configuration. |
| Sensor Misplaced | Inlet temperature is higher than outlet temperature while firing. | Verify inlet and outlet sensor placement. |
| Low Temp Lockout | Water temperature is below 36°F. | Verify actual water temperature and the inlet sensor. |
| Low Voltage | The 24 VAC supply is below 23 VAC. | Check incoming voltage, transformer output, and low-voltage wiring. |
Demand faults and lockouts
| Display or symptom | What it means | Manual-backed check |
|---|---|---|
| Water Sw Open | The water switch opened during a call for heat. | Confirm pump operation, clean the filter and baskets, and verify water flow before adjusting the switch. |
| Vent Sw Open | The vent safety circuit is open. | Check for vent obstruction and inspect the vent-switch circuit. |
| Hi Limit 1 / Hi Limit 2 | A high-limit circuit opened. | Check flow, pump operation, scale, and bypass condition. Correct the cause before resetting. |
| Air SW Open / Fan Lockout | The air switch did not prove; three air-switch faults create Fan Lockout. | Verify the blower voltage jumper, fan relay, connections, and blower operation. Fan Lockout requires a power cycle after repair. |
| Diff Sw Closed / Diff Sw Fault | The differential switch state does not match the fan state. | Check the switch, tubing, fan operation, and control wiring. |
| Ign Try Failure | The control did not establish ignition. | Verify gas supply, gas pressure, valve operation, igniter, burners, and ignition wiring. |
| Ign 60 min Delay / Ignition Lockout | Repeated ignition or gas-valve failures caused a timed delay or lockout. | Correct gas or ignition causes first. Ignition Lockout requires cycling power. |
| Flame Lost / Flame below 2 microamps | Flame was not proved or the signal is weak. | Check gas pressure, igniter condition, burner cleanliness, grounding, and flame-sense wiring. |
| Flame w/o CFH | Flame is detected without a call for heat. | Shut off the gas supply and have the gas valve and ignition control inspected. |
| Flue Over Temp | Flue temperature exceeded 390°F. | Shut the heater down, check flow and combustion, and power-cycle only after the cause is corrected. |
| Outlet Over Temp | Outlet water exceeded 180°F. | Check water flow, pump operation, scale, and bypass condition. |
| Low Flow / High Flow | Measured flow is outside the expected operating range. | Check filter, pump speed, valves, bypass, and the flow-sensor setup. Low flow can scale the exchanger; excessive flow can promote condensation. |
| Flue Low Temp / Flue Extreme Low | Flue temperature is below 175°F or 140°F. | Check for condensing conditions, flow, firing rate, and combustion. Extreme Low requires service before reset. |
| Remote Wire Err | Pool and spa remote inputs are energized together. | Correct the three-wire remote connections. |
Mechanical symptom checks
| Display or symptom | What it means | Manual-backed check |
|---|---|---|
| Whining or harmonics | Water or gas restriction, debris, scale, or Unitherm Governor movement can create noise. | Check water flow, chemistry, debris, restrictions, and governor movement. |
| Cycles on and off | Dirty filter, low water level, bypass position, or pressure-switch setup can interrupt flow proof. | Restore normal circulation before adjusting controls. |
| Sooting | Air starvation, improper venting, burner debris, governor problems, or improper flow can produce soot. | Shut the heater down and have combustion and venting inspected by qualified service personnel. |
Source and model boundary
Source: Raypak AVIA 264A/404A Installation and Operation Manual, Service Menus, Status and Diagnostics, and Troubleshooting sections. This guide summarizes only the listed model family. Confirm the model number and use the current manufacturer manual before service.