How hard to install a Honeywell TH8320ZW thermostat?

(Kurt) #1

I’ve got a small system up and running – mostly light switches and motion sensors so far. I’m considering taking the plunge and installing a thermostat. The TH8320ZW model is on the compatible devices list, but my question is around how hard it is to install? Here’s what the base plate of my current Honeywell thermostat looks like:

I know nothing about installing thermostats, but the wires look to be fairly well-labeled. Is it just a matter of connecting the same wires to the new thermostat in the right places?

Basically, if I just need to follow connect-the-wires, I can do that. Looking for an informed opinion before I take the plunge.


(Neil) #2

I have not installed a Honeywell TH8320ZW thermostat, nor do I know anything about its wiring (yet) but I am starting to look into it, too. So far I have only gotten to finding some links with information (below) but not a write-up about actually installing it which seems to differ depending on the factors such as age of original system install and presence of A/C (or not), etc.

Link to info about Wiring Color Codes

Link to page with links to Honeywell Manuals

Link to YouTube video about the unit

If you have not already found these (or similar) perhaps they will help. And I expect many of us will be interested in what you learn if you proceed.

(Blake Westerdahl) #3


I don’t know if I count as an “informed opinion” but I switched my existing Honeywell thermostat for the TH8320ZW.

From a wiring perspective it was super easy, I just made a note of which wire was connected to which terminal (i.e. G,C,R,W,Y in your picture) and then connected them to the same terminals on the TH8320ZW. Yours appear to be color matched (yellow wire to the Y terminal) so that makes it even easier (it been over a year since I did mine so I can’t remember if mine were that way).

The trickiest part was the programming. This is so the thermostat is communicating correctly with your HVAC equipment (nothing to do with the z-wave). Prior to disconnecting my old thermostat I printed out the manual to the new one (I can’t remember if this was included in the box but here is a link: ). I went through the settings on my old thermostat and found the correct settings in the TH8320ZW (Pages 7 and beyond) and made notes.

Once I physically installed the TH8320ZW, I just went through and entered the settings I had written down. I confirmed that the thermostat was working correctly with my furnace, and pairing it with my original z-wave hub was a snap. When I moved to SmartThings, I had to unpair it from my old hub and then pair with ST. Again it was a complete snap.

(Carl Aydelotte) #4

The only thing I want to add is check the required wires for the new thermostat. I installed a different brand/model and seem to remember having more wires in my wall, and it worked out for me because the extra wires were required for certain features of the new thermostat. Check it out before you buy just to make sure.

(Kurt) #5

So just to follow up on this, I installed two of these without any problems. @trotsky40 - thanks for the pointers on the programming. I spent some extra time up front making sure I had the necessary info from the old system to program the new one.

Beyond that, it was a very simple process and the wiring part was trivial. It helped that I have a newer house (~10 years old) that has modern wiring. I imagine older houses might not be as straightforward.

Anyway, for anyone else looking to do the same thing, hope this helps.

The SmartThings app needs some work in controlling these devices as it’s a bit finicky, but I will post that in a separate thread.