Affordable WiFi thermostat!


Update: This same thermostat is now available at Amazon [amzn] under the Homewerks brand for about the same price as Home Depot; take away tax and add free shipping and the price is comparable. They also have a fancier version [amzn] with a dot-matrix display and a few more features.  Read on for the original post…

I had posted another blog entry about these things almost a year ago – I had found the Radio Thermostat Company of America website, and their wifi-enabled thermostats looked like just the thing to add to my home energy monitoring setup.  However, they seemed woefully unavailable…

Then they started popping up rebranded, from Intwine EnergyOurhomespaces, Enphase … but in at least some of these cases it was a “we’ll sell you back your data for a monthly fee” arrangement – no thanks!

The helpful commenters on the earlier blog post alerted me to the fact that they are now in stock at the RTCOA website store, and also  available at Home Depot – $99 each place.  Further, there is an iPhone app to control it – no monthly fee involved.  I’ve asked on the RTCOA forum if there is an API to talk directly to the devices; I’d rather not be beholden to some 3rd party to get data in/out of the thing.  I may have to get one; these look pretty darned cool.

p.s. the cheaper 3M-30 and 3M-22 thermostats at Home Depot also have the U-Snap sockets for the wifi module, but so far that does not seem to be available separately.

42 thoughts on “Affordable WiFi thermostat!

  1. What’s the advantage of WiFi? Is it mobility, being able to, for instance, move the thermostat upstairs at night to keep it warmer/cooler, since that’s we we are?

    Also, is it hard to install — and I’m talking about for someone with no installation skills whatsoever (me ;-)

    • Wait doesn’t everyone want a wifi thermostat? ;)

      I think the main advantage for most people is that you can control it from afar – via web or iphone app. Whether “afar” is “up in the bedroom” or “on vaction and you forgot to turn it down before you left.”

      The thermostat itself stays on the wall; it is just controllable via network.

      I want it because I’d like to be able to query it periodically as part of home monitoring, i.e. graphs of setpoint vs. interior temp vs. exterior temp vs. furnace on/off would be interesting.

      How hard it is to install probably depends on details of your heating equipment; it does require a 24VAC line coming out the wall; I don’t know how common that is. You can take a look at the instructions on the product page

  2. I’m seriously considering getting the CT30 for my home, but haven’t had much luck at finding it at my local home depot. Also, your links are broken. Here is the link for the 3M-50 (the one that includes the wifi module priced at $99):

    Have you gotten one yet? So far, I haven’t found any real “hacker” reviews of these thermostats (most reviews are very basic users, not those interested in APIs and other such geekery which really interests me).

  3. I will purchase the Filtrete 3M-50 at HD for my home this week .

    I agree . I believe that Proliphix offers that option,

    “I’ve asked on the RTCOA forum if there is an API to talk directly to the devices; I’d rather not be beholden to some 3rd party to get data in/out of the thing”

  4. Got one last night so I’ll be putting it in this weekend, hopefully – the old thermostat has membrane keys and the up/down temp keys popped into the inside of the box, can only be adjusted with a penpoint, so it’s perfect timing!

    Anyway, I’ll try to remember to let you know.

    I’m with you, don’t want to be doing this stuff on an outside site – too much to fail. Hopefully the API publish will enable good daemon code on a Linux box instead of their too-public site.

    I have a 1964-made GE aircon and heater, soon to be replaced (just bought this place a year ago, replaced the PGE panel with the circuit breakers that never blow, and wonder of wonders, the aircon immediately started blowing its breaker!) so it should be interesting to see how the wiring compares with anything modern. I’m replacing a digital thermostat though, so that bodes well. Just worried about power to the new stat.

    After that it’s on to solar and power monitoring!

  5. Eric,
    Great blog post. I’m citing yours in my post on this same topic. While it doesn’t look like it has as much capability as the Ecobee unit, for 1/5th of the price it may be worth it!

    Here’s my write-up of the installation of the Ecobee unit in my home:

    I went to the Radio Thermostat product website but I’m having trouble finding information how to access the thermostat over the web?

    • Hi Chris!

      To access it over the web, you (as I understand it, still haven’t gotten one) sign up with, and from there you can use a web portal and/or an iphone app to control it. See

      There are also promises of a developer-friendly API for the device, so that people can invent new & cool ways to interact with it. Occupancy sensors? Sophisticated heating curve analysis & anticipation? I’m sure there are some neat things that could be done with remote control & more computing power than is usually present in a thermostat…

  6. Just put one of these in my lakehouse 200 miles from home. Been looking at the thermostat via website every day since. Very cool. It is not the easiest to wire unless you already have a C and RH wire to your thermostat but I found out if you don’t have both, the easiest to do is look at your furnace panel. If you have a C terminal, just run a new wire to your t-stat and connect the C. If you don’t have a C wire, trace the 2 low voltage wires leaving your furnace to your A/C unit. These are 24V wires. Just use the same terminal(s) to your t-stat and you are good to go (test by taking out your batteries, if the t-stat stays powered you have 24V connection). What I am waiting to find out is if the thing will re-connect after a power failure at the lake house (not uncommon). If it does, this thing is the best investment I’ve made in a long time.

  7. I also just installed this unit at my lake house this past weekend. The install went pretty quickly and easily. As long as your existing thermostat has heat, AC and fan options you should have all of the necessary wires to make the unit control your furnace. There are a couple things of note, if you don’t have the C wire and attempt to get the unit to work off of just batteries the unit will work just long enough for you to connect to it and then the wifi module turns off. After lopping the end off of a 12v 700ma power supply I had laying around and wiring that into the unit everything is working just fine. Another thing of note. 3M does not actually make these units but is just selling the rights to their name on an OEM product.

  8. This product is new and has some glitches that can probably be resolved with firmware upgrades. I hope that they act fast to make it more reliable.
    Until then, it is just a hobby gadget vs a reliable internet enabled HVAC
    thermostat control .

    If you currently need an internet managed thermostat for a location where reliability is critical (eg-: commercial or distant location) , look at paying the $200-$400 for a Bayweb, Ecobee or Proliphix IP themostat .

  9. I just bought this Filtrete 3M50 From Home Depot store for $99 last week and installed it today. Here are some key points I like to share:
    – It made installation easy by create its own wifi adhoc network that you connect to it from your computer.
    – your wifi network MUST be WPA2. I had WEP before and it will not work, even though the dropdown has ‘WEP’ as a security selection after you connect to the adhoc network on the thermometer, it just kept coming back with invalid password even after I typed in the correct passwords over 5 times.
    – since the thermostat has its own client making outbound connection to filtrete’s server, there is no firewall and router forwarding issue usually associated with inbound initiated connections.
    – has a web site feature to have it email you if the server cannot contact your thermostat, which is a good free service (e.g. power failure, network failure, etc.)
    – PC or iPhone adjustment is not instantaneous. I stood in front of the thermostat while changing temperature on my ipod touch thinking I would see the reading on the thermostat update immediately but it didn’t. There’s a small lag probably due to client to server polling or vice versa.

    All in all I am VERY GLAD with the purchase. I have been waiting for something like this for my 2nd home and the price point is fantastic considering a good brand non-wifi thermostat can run around $75 already.

  10. Michael, How did you correct the wifi network issue? Is it the router? i.e. the Linksys or whatever system you have in your place? I just bought one, but have yet to install it, and have NO idea what my wifi system is. How do you find out what it is?

  11. Before you start, see the installation videos and browse the threads at .

    You will need to login into the router to find the WIFI security settings . The major brand routers have good manuals online . If your change from another WIFI security protocol to WPA2 , remember that you will need to do all devices that connect to the router ( computers, IP cameras etc ).

    Better yet, find a friend who is more familiar with wireless networking to help you

    Before you start, see the installation videos and speend browse the threads at .

    After you get it operational , you might want to consider getting the supplemental program at for enhanced features .

    JoAnn says:
    March 7, 2011 at 7:30 pm
    Michael, How did you correct the wifi network issue? Is it the router? i.e. the Linksys or whatever system you have in your place? I just bought one, but have yet to install it, and have NO idea what my wifi system is. How do you find out what it is

  12. Thanks Charles. None of my friends are very technically savvy, unfortunately. I’ll muddle through… and for some reason that forum link isn’t working for me. I’m on a Mac, but that shouldn’t mater for a forum. the ‘setyourthermostat’ is for windows, but I’m sure there’s something similar for Mac.

  13. Does the 3M50 have the ability to send alerts – if the temp and or humidity exceeds a certain point? Actually, the way I intend to use it, if it just alerts me that it has energised (turned on) that would work for me.

    Can it do that?

    • The thermostat itself does not (and for the record, the 3m50 doesn’t measure humidity, but the nicer thermostats from RTCOA do). They do have an API to talk to the thing though, so doing your own monitoring & alerting would certainly be possible. You can monitor current temp, set temp, current mode, current run state, etc…

  14. Anyone know if the wifi thermostat has wireless remote sensors? I need the thermostat to get temp reading from another part of the house.

  15. has anyone had luck with the att u-verse wifi network?
    Planning on investing on one the filtrwte, but I need to rewire bc i am lcking the c wire and wanted to make sure it is worth it

    Thanks for your input, Williers

  16. Wish I could hire one of you ‘hackers’ to set me up here in Gary, Indiana! :)
    But…I just want a ‘remote’ly controlled TStat so I can merely START & STOP my HVAC unit, as my skin dictates — rather than on the basis of 1 or 2 degree settings/sensitivity.

    I rarely go anywhere, so I do not need the ability to control from remote locations; rather, from right here – 10’ away from the wall unit. (No….I do not want to get more exercise, jumping up and down 30 – 50 times an hour!)

    My problem is that I’m either too hot or too cold, and the TStat does not offer gradients of control of less-than-standard (1 or 2 degrees, whatever is the norm).
    My solution is to just turn it on and off, as needed.

    Your thoughts/solution? (I don’t see it here on this blog, but maybe… can help me?) Thanks for any replies!

    • Some thermostats have a “swing” setting which determines the temp range, some go down to 0.5F for swing. That might help.

      But you might also consider a home energy audit to see if you have insulation or air leak problems which are causing drafts or otherwise creating comfort issues.

      This thermostat can also be controlled via a smart phone so you could do manual control from your la-z-boy if you really want to. :)

  17. On initial installation I could not see the Thermostat on my wireless laptop. I was told by the help desk that I needed an iPad or iPhone to set up the WiFi and it could be controlled via Android device or a wireless computer. Even after borrowing an iPhone to set it up I could not see the device on a wireless laptop or Android device. After I had given up on the wireless programming the Manual Programming failed 1 week later. I bought a Honeywell and it worked like a dream so buy the Honeywell.

    • Byron, sorry you had trouble with it – I’ll agree that the setup is a little finicky but in the end I didn’t have too much trouble. FWIW, there are phone-less setup guides for Windows and Mac as well.

      Anyway, glad you found something that worked for you.

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