How to Install a Programmable Thermostat

I’ve always wanted to install a programmable thermostat, but have been a little intimidated by the thought of any DIY project that involves wires.  What can I say, I’m a chicken when it comes to anything electrical, and usually resort to searching Angie’s List for a reputable electrician.  After reading a few “How-to” articles online I summoned the courage to check out a few models of thermostats.  I found that like most everything electronic, there is a range of options to choose from ultra-cheap to over-the-top expensive.

Our old, original thermostat

We settled on a medium-grade model, not the cheapest, but not the most expensive, either. It was a 5-1-1 GE Honeywell programmable thermostat (the 5-1-1 means you can set a weekday schedule and a Saturday/Sunday schedule, independently).  This feature appealed to us because our weekday schedule varies from our weekend schedule, as I suspect is true in most households.  With new thermostat in hand, I’m ready to tackle the installation.

Disclaimer:  The following instructions are for inspirational purposes only, and are not meant to substitute manufacturer instructions that come with your particular model.

Step 1 – Turn off all power at main electrical panel.   Some instructions I found online advised to simply turn off power to the room your were working, others suggested throwing the main switch.  I always lean towards safety and decided to turn everything I could find on the electrical panel to the “Off” position.

Our old thermostat, minus cover and control board

Step 2 –  Remove cover and control panel from old thermostat.  The cover and control board on most models snap off–look for a recessed lip around the sides or bottom of the original thermostat where you can grab and remove the faceplate and control board.  Take care setting this aside as you may have to reinstall if something goes wrong further in the installation.

Step 3 – Label wires according to their current position, and remove them one by one.  Most new models of programmable thermostats come with sticker labels that you can use to wrap around the wires coming from the wall.  If your package doesn’t contain pre-printed labels you can substitute with masking tape and a Sharpie.

Step 4- Remove old thermostat plate from the wall.  Be sure not to let the mess of wires drop back into the wall when unscrewing the old plate.  Some instructions recommend taping a group of wires to the wall, but I found that the wires were so stiff that simply spreading them out a bit adequately prevented them from dropping back into the hole in the drywall.

It’s a good idea to use a level–I did when drilling, but not when taking the photos!

Step 5 – Attach new thermostat plate to the wall.  Most of the time a new model’s plate will not match up to the existing holes from the old thermostat.  This was the case with our model.  I simply drilled a couple holes for the new thermostat, and inserted the drywall anchors that came in the new packaging (don’t worry, the instructions accounted for this by indicating the drill bit size to use, etc.).  Go ahead and insert batteries if your model requires them.  Our model required two AA batteries (installed just above the wire connections) to hold the programming settings in the event of a power outage.

Step 6 – Reattach the wires according to their label and the corresponding spot on the new thermostat.   This was the most difficult part of the entire project because there wasn’t much room to work with, and depending on your heating/air conditioning system you could have several wires to attach.  We finally managed to get them all attached and were ready for the final installation step.

Step 7 – Attach control panel and face plate for new thermostat*.  This step reminded me of attaching an old parallel printer to a computer–simply match up the pins on the control panel with the pins on the back plate attached to the wall.

*Hint:  Make a handwritten note of the wires you attached (C, G, Y, R, etc.) before covering with the new control panel and face plate.  You’ll need to know this to properly program your new thermostat based on the type of system your have.  I didn’t know this ahead of time, and had to remove the faceplate to remember the letter designations I had attached.

You can see it got a little warm in the house with the power off!

Step 9 – Turn power back on and program new thermostat according to manufacturer instructions. We ran through the programming setting for weekdays, and then Saturday and Sunday.  In the summer time we let the temp get a little higher at night and sleep with ceiling fans running.  Before we wake up the thermostat is programmed to cool things down for getting ready for work and school, and then returns to a higher temperature for the day.  In the winter, we’ll reverse this process by letting things cool down after we are tucked away in bed, and warm things up during the early morning hours.

I haven’t received my power bill yet, so I can’t report on the savings (but I will in a future post). I imagine the long periods at night, and during the day, with increased temperatures will help reduce our power bill during these dog days of summer.

Still need help? Search Angie’s List for a recommended electrician in your area.

Relieve yourself from the cost and hassle of home repairs with a home warranty from American Home Shield.


  1. Oooh, fancy! 🙂

    I’ll share some advice that I learned the hard way. When installing a programmable thermostat, it is extremely important that you get the right kind. There are two main varieties- low voltage (for oil furnaces, etc) and high/line voltage (for electric heat). Make sure you’ve got the right one!

  2. I’ve done this project several times. Further to MoneyGrubbingLawyer’s comment, heat pump thermostats are a unique breed altogether because of their staged heating cycles. So be very careful in selecting the right product if you have a heat pump system.

  3. Thanks, Like Pete I keep meaning to do this as well. I’ve been attempting to turn the temp up when I leave, and back down when I get back, but I realize I forgot today. This might be the motivation I need to do this over the long weekend.


  4. Excellent post! My programmable thermostat definitely comes in handy for those times when I forget to adjust the temperature before I leave the house or go to sleep.

  5. I got one of these right after I moved into my new home. It is great, I know that I would forget to adjust it when I leave in the morning, and it is set to start cooling a bit before I get home. If you have a regular schedule away from the house it is great! Oh, if I recall I didn’t shut off any electrical power at my house when I installed it! Probably a good idea to do so though.

    One last thing you might watch for in choosing is how many adjustments you can make in a day. Most seem to be 4 which should be enough.

  6. Good for you! I purchased a programmable thermostat TWO YEARS ago and was too intimidated to install until just last month. Turned out to be so easy! In addition to the ability to program it, mine came with a built in “Energy Star” program, which is supposed to be the most enviromentally friendly setting. I know the daytime setting is 85 degrees. I’m trying to live with that for awhile and see if I can stand it. I’m just about to get my first bill after a month of having it. If nothing else, it certainly looks better!

  7. I’ve installed many programmable thermostats in the various houses we’ve lived in and have been pleased with the cost savings.

    Initially, I bought a mid-priced model (times were TIGHT then!) and it did well. In the next house I “upgraded” and ended up replacing the unit about every 2-3 years. They don’t seem to last.
    My last house had a home warranty on it, and the warranty company wouldn’t cover heating systems that had this type of thermostat. Seems that the thermostat is frequently the cause of the “no heat” calls. I was pretty frustrated with the quality of the high end ones. I learned to save the package & receipt.

    In my current house I have an inexpensive one and it’s been working WELL for over four years.
    So, you don’t always get what you pay for!

  8. Great instructions – now if I just had something to run with it????

    Won’t work with the woodstove, ya know 🙂
    Nor with the bathroom heaters…. oh well, I
    think the exercise of gathering and storing firewood in the summer, and handling firewood the other 9 months should be good exercise in retirement 🙂 Old fashioned, but it works.

  9. Other people have said to make sure that your thermostat instructions matches the type of heating system (gas, electric, or heat pump). I had to also call the thermostat company with the brand of my heating system. It turned out that the “all other” instructions with my thermostat did not fit my brand (Trane, a BIG manufacturer!). Since I owned a builder-special heating system which did not have a fuse in the right circuit, I had to call an electrician to fix it (replace a small transformer) then install the thermostat. Yes, I still advise replacing your own old thermostats with new programmable models- just read the instructions first, and call the help line with questions.

  10. @MoneyGrubbingLawyer
    It’s very good to know about there being a specific type of thermostat for oil furnaces. Thanks.

    @Todd A
    Hey, my thermostat resembles that comment! (But maybe not for long….)

    Great post. I’ve also been very intimidated by the thought of doing this myself but it would save me a lot of money at our rural home over the winter.

    We keep the temp up all the time there in the winter because when we arrive there it’s often 2 or 3 AM and we have a small child, but we only go for one day per week (and not nearly every week when there’s a lot of snow in the mountain passes).

    A programmable thermometer would let us set it just warm enough for the pipes not to freeze through the week and then warm it up a few hours before we would get there. I don’t mind the idea of heating it up once a week whether we’re there or not. I’d still be saving 6/7s of what I’m currently paying.

  11. I replaced our ancient rotary dial style thermostat to the very same model you used almost 2 years ago and it has been great! I had started thinking about doing this several years ago and I regret that I was intimidated enough by this that I procrastinated. It’s an incredibly simple project and you’ll recoup the expense of the new thermostat in no time at all.

  12. I’m not a frugal dad, but am a frugal mom! I purchased the Honeywell 5.1.1 also and just installed it. I was afraid of the electrical but read that these are low voltage. I’m happy to say that it seems to work correctly – furnace starts and stops according to temperature setting. Can’t wait to see if it really saves money this winter.

  13. i want to know the stpes about installing a heat pump thermostat with e-heat.
    i checked some models, but i do not understand about take out or not the jumper in the new thermostat.
    thanks , elmer

  14. I have a property we can’t sell so we are renting it as a vacation rental until we can find a long term renter. Right away, I found that no one will be the least bit conscientious about the A/C temp. They had windows & doors open and the A/C was set at 65*. Needless to say I was not happy about that, nor was I happy about the slobs throwing wet towels every where on my new wooden floors and antique dressers. So in the future to avoid this rudeness, I plan to install a thermostat that I can program, however I want one that is not re-programmable by anyone else. What do you recommend? I was thinking some thing that has a code, I’d hate to lock it but I will if I have to.