Raypak Pool Heater Liming or scale forming in the exchanger Error Code

Updated 2026-08-30 · review status: manual-verified · reviewed by MiniSplitDecoder Editorial Team Last verified: 2026-08-30

Check your model first

  • Digital 206A-406A
  • Digital Low NOx 207A-407A
  • Professional 268A-408A
  • Above-Ground 106A-156A
  • Digital 206A-406A / Low NOx / Professional / Above-Ground

Match the model on your equipment label to the linked manufacturer documentation. The same code can mean different things across model families.

Quick answer

Correct pool water chemistry first. Inspect the bypass for movement and replace if none; replace the U.G. if it doesn't move when heated.

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 Liming or scale forming in the exchanger means

Correct pool water chemistry first. Inspect the bypass for movement and replace if none; replace the U.G. if it doesn't move when heated.

Code meaning varies by series

  • Digital 206A-406A / Low NOx / Professional / Above-Ground: Pool water chemistry out of range (see water chemistry section), bypassing too much water (inspect bypass for movement and replace if none), or U.G. not functioning (replace if no movement when heated).

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

  1. 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. 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.

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Sources

Related Pool Heater guides

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