Raypak Pool Heater Low Temp Lockout / Low Voltage Error Code
Check your model first
- Professional Series X94
- Professional Series SR-410
- X94 / SR-410 (Professional Series Digital)
Match the model on your equipment label to the linked manufacturer documentation. The same code can mean different things across model families.
Quick answer
Water is below 36°F, or control supply is below 20 V.
Severity: high · DIY difficulty: easy
Safety
Stop at the exterior: power-cycle at the disconnect, clean the filter/basket, and check for obvious water-flow blockage. Pool heaters combine gas piping, 240 V wiring, and (on heat pumps) refrigerant — burner, control-board, and sealed-system work requires a licensed technician. If you smell gas, shut the gas valve and leave the area first.
What Low Temp Lockout / Low Voltage means
Water is below 36°F, or control supply is below 20 V.
Code meaning varies by series
- X94 / SR-410 (Professional Series Digital): Low Temp Lockout: ignition control shut down heat because water temperature is below 36F (2.2C). Low Voltage: displayed when supply voltage is below 20V (no operational changes).
First checks before service
1. One-time fault event (power disturbance or transient sensor reading) common DIY
Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.
Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.
2. Fault persists after a clean reset occasional pro only
Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).
Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.
Sources
- PoolDial error-code reference (manual-backed) — verified 2026-08-29
- Raypak Professional Series X94 Installation & Operation Manual (241494), Table N Error Condition Messages — verified 2026-08-29