Honeywell Home thermostats: messages and settings explained

Which Honeywell Home thermostats does this site cover?

The pages on this site are checked against the manuals for these models, and each page names the model its figures come from:

• T4 Pro Programmable (TH4110U2005, TH4210U2002)
• T6 Pro Programmable (TH6320U2008, TH6220U2000, TH6210U2001)
• VisionPRO TH8000 Series
• FocusPRO S200 Series and ElitePRO, which use a longer status message, "Waiting For Equipment"

Honeywell Home thermostats are made by Resideo Technologies, which uses the Honeywell Home name under license. That is why the manuals and support pages live on Resideo websites.

If your model is not on the list, the general behavior described on these pages usually still applies, but the exact menus and numbers can differ. Check the document number on the guide that came with your thermostat.

Where are the settings on a Honeywell Home thermostat?

On the T4 Pro and T6 Pro, the buttons on the face do most of the work:

• Mode cycles through the system modes. On the T6 Pro those are Auto, Heat, Cool, Em Heat and Off, though the guide notes that the modes available depend on the model and on how the thermostat was set up.
• Fan cycles through the fan modes. The T4 Pro offers Auto and On. The T6 Pro adds Circ, which the user guide says runs the fan about 33% of the time to circulate air.
• Menu opens everything else, starting with the schedule (shown as PROG) and the time and date.
• The arrow buttons change the setpoint and move through menu options, and Select confirms a choice.

Deeper options, such as how many times an hour the system may cycle or how long compressor protection lasts, are installer settings. Resideo numbers them; compressor protection on the T6 Pro, for example, is option 387. Those are meant to be set once by whoever installs the system.

What do the status messages mean?

The T4 Pro product guide lists the status messages these thermostats show: "Cool On", "Heat On", "Em Heat On", "Recovery" and "Compressor Protection". Each one is covered in detail on its own page:

• "Cool On" or "Heat On" flashing, or "Wait" on the screen: the thermostat is holding the compressor off for a few minutes after it last stopped. See thermostat blinking "Cool On" and why your thermostat says "Wait".
• "Em Heat On": emergency heat is running, which is not the same as auxiliary heat (AUX). See AUX heat vs emergency heat.
• "Recovery": the thermostat has started heating or cooling early so the house reaches the next scheduled temperature on time. See thermostat recovery mode.
• Hold messages: a temperature you set by hand is overriding the schedule. See hold vs permanent hold.

Is there anything Honeywell warns about in cold weather?

Yes. The T4 Pro product guide warns that, to prevent possible compressor damage, you should not run the cooling system when the outdoor temperature is below 50°F (10°C). If the house feels warm on a cold day, open a window or lower the heat setpoint rather than switching to Cool.