Aqua-Hot AHE-250-D03 error code D5 LED OFF (OVERHEAT INDICATION)
On the AHE-250 relay control board D5 = Burner Status (green) -- it illuminates when the burner switch is ON and the control thermostat is calling for heat. D5 is NOT an overheat indicator. If D5 is off, the burner is not being commanded (burner switch off, no heat call, or a burner-circuit fault). The overheat condition is signaled separately by the manual-reset burner/AC high-limit thermostats (215degF trip), not by a D-LED.
What to check, and in what order, is in the app. The flow Aqua-Hot — Fluid Level Check & Refill Procedure walks this code step by step with the pass/fail measurements, wiring schematics and procedures that go with it, and it works offline in the bay.
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- Aqua-Hot 200-Series 250P/250D Service ManualAqua-Hot
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