ℹ
info Honeywell
Status Heat On
Heating system is activated and running.
? What Causes This
Indoor temperature has dropped below the set heating temperature.
ⓘ What This Means
This is normal operation when heating is needed. No action required.
Source: page 7 of the official manual
From the manual
This error code appears in:
Honeywell Th8320U1008 Thermostat