Honeywell T4, T4R, T4M Troubleshooting Manual

Troubleshooting

If you have difficulty with your Thermostat, try these suggestions.
Most problems can be corrected quickly and easily.

All models
Screen is blank	Replace the batteries (T4 & T4R only). Check the OpenTherm boiler has power (T4M only). Contact installer.
Thermostat shows	Batteries have less than 10% power and need to be replaced soon.
Thermostat is flashing	Batteries are critically low and need to be replaced immediately - see 'Changing the Batteries'.
Thermostat shows but the boiler does not switch on.	The boiler cycles on and off as it controls the temperature, and sometimes the icon will be displayed when the boiler has cycled off. If the boiler doesn't switch on after a long period of time contact your installer
Heating system does not respond to temperature adjustments.	Make sure the set temperature is higher than the actual room temperature. Check the heating system is powered on. Check the Receiver Box is powered and the Thermostat has a wireless signal (T4R only).
Thermostat shows	The temperature sensor of your Thermostat is faulty, contact your installer to repair or replace the Thermostat.
T4R (Wireless) Thermostat & Receiver Box only
Thermostat is flashing and Receiver Box LED is flashing RED.	Wireless signal lost - Move the Thermostat to another location to try and restore communication.
Thermostat is flashing and Receiver Box LED is off.	Check Receiver Box has power by pressing the button to switch boiler on. If Receiver Box has power then no wireless binding data stored - Follow binding procedure in the installation guide or contact your installer.
Receiver Box LED is flashing ORANGE.	Receiver Box is in binding mode - will time out of this mode after 3 minutes.
T4M (OpenTherm) Thermostat only
An OpenTherm boiler can report alerts back to the Thermostat which can be useful when contacting an installer or maintenance engineer. You can view these in the 'OpenTherm boiler alerts' menu.
Description	ID	Error code	OT Reading
Service request	001	01SR	0 = service not required 1 = service required
Low water pressure	002	02WP	0 = no WP fault 1 = WP fault
Gas/flame fault	003	03GF	0 = no GF fault 1 = GS fault
Air pressure fault	004	04AF	0 = no AP fault 1 = AP fault
Water Over Temperature	005	05WT	0 = no OVT fault 1 = OVT fault
OEM specific	006	06OS	Boiler manufacturer specific code

Documents / Resources

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Here you can download full pdf version of manual, it may contain additional safety instructions, warranty information, FCC rules, etc.

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