I have a Honeywell thermostat which reads low battery. I replaced the batteries with fresh batteries and even turned the circuit breaker off and on. Yet it still reads low battery and there is no heat coming from this section of the house. (Master bedroom is cold) What do I need to do?

Many times a reset button needs to be pressed with a paper clip etc, to restore operation after replacing the battery. Check the manual.

Hit the reset button

I have a Honeywell programmable thermostat which was installed about 3 years ago. The screen reads "Low Battrey" but I do not know how to open it to replace the batteries. There does not seem to be any way to open it.

The older models do not have a reset battery so this is what I did to reproduce a reset.

Remove the old batteries.
Install the new batteries with incorrectly facing terminals. (+ goes to - and - goes to +). This will completely power off the unit.
Remove the incorrectly installed batteries and let the unit sit for about 15 seconds.
Install the new batteries correctly - the unit should now start flashing 12:00 time - you're all set!
Set the time and date and you're ready to roll.

Hope this helps someone!

fullwit s totally right. Just install the batteries incorrectly for 15 seconds and then install them in the unit correctly and you should be good to go!

Reversing polarity did not work for us. Any other suggestions.

The polarity reversing scheme has worked for me. I now have heat. Thank you Fullwit.

Thanks! This did the trick!

Reversing batteries helped here too!
Thanks!!

My Trane XT 302 wall thermostat says on the display it needs new batteries. I had it professionally installed and don't seem to have the manual. How can I open the wall-mounted thermostat to replace the batteries. I've looked carefully around all the edges and there are no markings to open.

Thanks---Hope you can help! It's a heat wave and my ac seems to have stopped along with the thermostat.

Try to squeeze in different areas to separate the front from the back.
Change batteries quickly and don't press any buttons to maintain any Programming.

You manual is here: Trane OWNER'S GUIDE Thermostats XT300C, XT302C | ManualsOnline.com (http://homeappliance.manualsonline.com/manuals/mfg/trane/xt300c_xt302c.html) for free.

I'd suggest calling the help line because there is no reference to a battery even though there may be one. Sometimes a small lithium batter which is deamed non-user replaceable is inside the thermostat. It's only purpose is to maintain the settings when the power goes out and therefore the battery may have a 10 yr life. That lifetime may the manufacturer's expected lifetime for the thermostat.

Thank you fullwit! Your suggestion worked!! :)

This trick still works. Was able to reset my thermostat after battery change.
Thanks!

You might also find that shorting the battery contacts with the batteries out will also work. Install the batteries quickly as if they are a switch.

I was losing my mind with confusion. That was so simple. Who would know that?

Thank you!!

Reversing batteries worked! Many thanks for the great advice!

fullwit, you rock :)
Thank you very much.

The older models do not have a reset battery so this is what I did to reproduce a reset.

Remove the old batteries.
Install the new batteries with incorrectly facing terminals. (+ goes to - and - goes to +). This will completely power off the unit.
Remove the incorrectly installed batteries and let the unit sit for about 15 seconds.
Install the new batteries correctly - the unit should now start flashing 12:00 time - you're all set!
Set the time and date and you're ready to roll.

Hope this helps someone!

Thank you fullwit
You da man!

Years later and that solution worked for me too. Thanks fullwit!

Thanks, reversing batteries worked.

Reversing the batteries did not work for me. I did all this plus pushed the reset button and still says low battery.

Verify your battery voltage.
I wouldn't try reversing, although it appears to work for many. I think just pressing the buttons with the batteries removed would discharge the internal capacitor. Some electronics have a protect diode to protect from reverse polarity, and can damage? My Opinion?

Reversing batteries helped! Thank u so much!

Switching the batteries the wrong way worked for us too! Thank you!