Honeywell Home Error Codes & Diagnostics

Honeywell T6 not calling for heat: installer settings before faults

A Honeywell T6 that shows a set point above the room temperature and still produces no heat is either being prevented by a configuration parameter or is not connected to what it thinks it is. Installer setup decides system type, staging, changeover, and minimum off times, and each of those can suppress a demand that looks perfectly reasonable on screen. Applies to: Honeywell Home T6 programmable thermostats configured through installer setup parameters T6 covers wired and wireless variants across several markets, with installer setup parameters that differ between them. The installer setup guide for the exact T6 variant you own is the reference, and a parameter number from a different variant can select something else entirely. Owner-safe checks: Confirm the time, the day, and the schedule on the thermostat, and check whether a hold or a temporary override is active. | Raise the set point by hand and note whether heat arrives, which separates scheduling from everything downstream. | On a wireless variant, look at the receiver near the appliance and note whether it indicates a demand. Qualified technician: Installer setup parameters govern which terminals are energised and how equipment is staged, and selecting the wrong system type can make a thermostat energise a circuit the equipment does not expect. | Terminals inside a boiler or a wireless receiver sit at mains potential in British installations, which puts any work on them outside what an occupant should attempt.