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critical Aprilaire

Error Code Red Service Light

Indicates that service is urgently required due to high electrical demand and can only be resolved by cleaning/rinsing unit/canister.

? What Causes This

Humidifier detects excessive current draw despite multiple drainage attempts, indicative of severe mineral blockage in electrodes or water pathway system.

How to Fix It

Shut down humidifier, clean the interior components including removal/replacement of steam canister; consult service if not resolved manually;

Source: page 27 of the official manual

From the manual

Manual page 27 — Aprilaire error Red Service Light

This error code appears in:

Aprilaire 800