Removing COM Module from Honeywell UtilityPRO

A few weeks ago, my apartment complex installed new UtilityPRO programmable thermostats in all of the units. As part of the CPS Energy Peak Saver program. Quite a convenient little gadget, but a little creepy too. With this thermostat, CPS has the ability to modify the temperature remotely without me knowing. Although I personally couldn’t care less, I spoke with some friends who didn’t like this idea. So that got me thinking — I wonder how difficult it would be to disable this remote access.

A little googling revealed that the thermostat I had was a Honeywell UtilityPRO, which handles remote communication through the ZigBee protocol. With this knowledge in hand, I did what any good computer scientist would do and ripped the damn thing apart (carefully, of course). What follows are the steps that I followed in removing the ZigBee COM module, which in turn disabled any remote communication with the thermostat.

Note that this very possibly violates some contracts (depending on how you received your thermostat), voids the warranty, and not only prevents your energy provider from remotely changing your temperature, but also prevents you from remotely changing the temperature. Follow the following steps at your own risk.

Please feel free to leave your comments below!

Thermostat - Intact
Before you begin, your thermostat should look something like this.
Thermostat - Back Cover
After pulling it off the wall, you should see these four points. Releasing them allows you to remove the faceplate. This part is easier with a second set of hands, but possible on your own.
Thermostat - Front Cover Removed
Once you’ve released and removed the faceplate, the screen will be fully accessible. Lift the screen out.
Thermostat - Under the COM Module
You’ll now see the COM module, but you’ll need to remove it from the back.
Thermostat - Opening COM Module
The plate covering the back of the COM module can be removed as seen here. You’ll need to release from the front while removing it from the back.
Thermostat - COM Module
You can now lift the COM module out.
Thermostat - Connection Error
Once returning everything into the thermostat shell (minus the COM module) and re-attached it to the wall, you should see a screen similar to this. Note the “communication failure,” which indicates that you’ve successfully removed the COM module.

13 thoughts on “Removing COM Module from Honeywell UtilityPRO”

  1. Cool post. I have this same thermostat but thinking of getting a nest because I don’t like that they have control over my house temperature. One question I have is, can it still be programmable after the COM module is taken out? I’m thinking the programmability is all offline, right?

    1. Hi Art,

      Glad you liked the post!

      Yes, removing the COM module only disables communication-related functionality. Since the thermostat retains the programmed schedule locally, all of that will still work as it did before.


  2. Thanks for the post! Can you say if the ZigBee module is capable of 2-way transmission? There seems to be a lot of confusion around regarding whether utility companies can glean information regarding your heating/cooling use.


    1. According to Honeywell’s press release, the UtilityPRO can do one- and two-way communication. I can’t tell your for certain whether this means that all UtilityPROs can do both or that some can do two-way and some can’t, but my guess would be that there are two versions, one that can and one that can’t.

  3. Hey Dan,

    Just received notice from my apartment manager that CPS will install a Honeywell UtilityPRO thermostat in my apartment next week “In an effort to help you save money and be more comfortable…” The apartment manager did not mention the financial incentive THEY will receive from CPS for doing this. Funny how that works, I pay the utility bill and they get the financial incentive. Anyway Dan, thanks for the great post. I will put it to good use!

  4. I used to work for a Hydro Utility and was trained in this area.

    The thermostats are paired to your hydro smart meter using a wireless mesh protocol, the thermostats itself send the information through your hydro smart meter, then your hydro smart meter sends its information to the repeaters or data collectors, this is how they can communicate through your thermostat.

    Your Hydro company will eventually see the thermostat is not meshed/not communicating with the local regional collector, and will dispatch or send somebody in the neighbourhood. they will first try to communicate with it from outside using their laptop and antenna, if that fails, they will indicate its not communicating and then your hydro company will send somebody to replace it as per the agreement for using it.

    1. Good to know, Ravish! I guess if someone chooses to do this, they’ll want to replace the removed part whenever anyone enters their home to service the thermostat. I imagine this would cause quite a bit of confusion for whoever came to service the unit if it suddenly began working every time they were about to try to fix it!

    2. Hello! Rather than removing the COMM module, would you have any knowledge on the “secret” settings a utility uses to set this thermostat up? Possibly the communication setting could just be turned “off” somewhere in the thermostat’s settings? For example, there are a whole list of “secret” installer settings when holding down two of the 5 blank buttons that are near the bottom after pressing the SYSTEM button. Then a different combination of 2 buttons brings up a bunch of different sets of numbers which I assume are the “secret” settings for the utility to connect to the thermostat. Someone has to have documentation on what these secret settings mean and/or do. Do you have any info on this? Thanks!

      1. Hi Steve, good question! I don’t have any knowledge of those settings, but it’s an interesting question. If you discover any documentation (or sniff out these settings’ meanings yourself), I’d love to hear about it.

  5. Most of the codes are published in the ibstallation manual for the generic Vision Pro TH 8320, but not the meaning of 0390, 0400-0490, etc…. someone must have those codes, or be brave enough to experiment with them !

    BTW, thanks Dan, I bought one of these used and removed the comms moduoe – works perfectly.

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