Official WiFi Thermostat thread

I am installing the 2 touchscreen Honeywell thermostats I bought today so I'll document the process including pics.

I had a challenging install due to lack of a c wire so I'll also show you how resolve that easily.

My total cost was $180 for both thermostats and the c wire kit! Well under the cost of a single nest unit plus this Honeywell is the darling of the diy forums. Check out the review below and I'll be back later with a full write up!

Bonus that WINK just confirmed this unit works in their ecosystem so if that's important to you, you're future proofed with this unit.

Honeywell 8580 vs NEST


STEP 1 PURCHASING.
You can get this unit for $150 from HOME DEPOT or $70 from Amazon Warehouse deals. The top seller listed here (MS WORLD 3 LLC) is the vendor I used and the units arrived nearly perfectly. Total was $141 for 2 units ( I need downstairs & upstairs both)

$68 Touchscreen Honeywell WiFi Unit

Next I thought I was going to need a venstar add-a-wire but it turns out I had hidden c-wires already that were disconnected. IMPORTANT - You need to check this out yourself prior to install so you know if you need to buy a kit or not.

$22 "Add a Wire" C-wire adapter kit


Next, you need to understand a bit about how HVAC works. Most conventional units have a fan, furnace and air compressor. This is your typical "4 wire" setup, that looks like this:

W wire (usually white) - HEAT
Y wire (usually yellow) - AC Compressor
G wire (usually green) - Fan
R wire (usually red) - 24 VAC (24v power)
C wire (usually blue) - 24 VAC common.** **required by honeywell but might not exist or not be connected depending on the age of your HVAC.


Ok, with me so far? For old mercury-based thermostats, those are all the wires you'd need.

The magical C wire or 24 VAC Common is simply an extra powered wire so you don't have to install a mercury-based switch but can instead use a power thermostat instead.

FYI Heat pumps require additional wiring and I won't go into that but read here to your heart's content for more detail:

What are all those wires used by my HVAC?


STEP 2 INSTALL THERMOSTAT SIDE
I have 2 units; upstairs & down. The downstairs unit is 'all in one' (furnace and compressor) located in that big rectangular box.

The upstairs unit has the furnace in the attic, and the compressor outside.

***PRIOR TO INSTALL*** you need to make sure you've turned all the power off!! The outside fusebox I had has one for each..but it did not turn off the furnace for my upstairs unit..only the compressor. Make sure you've killed power to both before starting.

Ok, first thing is I pulled the old unit off the wall & discovered there was actually a hidden c-wire. This made the job a little easier. See the hidden c-wire below?? Its actually wrapped around the wire insulation so I didn't realize I had one. LOOK FOR THIS FIRST BECAUSE IT WILL SAVE TIME & MONEY!



Now you just need to remove the old plate, make SURE the wires are labelled if not already (Honeywell includes labels in the kit) and simply line 'em up. RWYCG..with the "C" being the blue wire you just unwound from the wiring bundle.



STEP 3 - HOOK UP THE C-WIRE on HVAC
My access plate for my Bryant/Carrier clone is the right most front panel. Takes about 30 seconds to unscrew it. Here's what it looked like:



Ok, so first thing I realized is my unit isn't using SCREW DOWNS but the thermostat wires (the tiny wires) are spliced into the HVAC wires via electrical caps (see red box)

So the next step is to find the other end of the C blue wire (it was wrapped around the cable at this end as well) and connect it up. The "C" wire on the HVAC is brown. I've pointed out where it connects to the circuit board with the black arrow in this pic.

Make sense? Now all you have to do is wire the brown to the blue and you have common (below)




That's it! Once that's done, turn the power back on and go plug in the front of your thermostat plate if you haven't already.

Now, for the UPSTAIRS unit, its a little different. I had to locate the wiring patch panel in my furnace in the attic, and locate the common there as well. It was actually using the screw downs so it was easier to locate.



I did not touch the existing wiring, I just unscrewed the COMMON screw, stripped the blue wire and screwed it back in and turned the power back on (both at the compressor outside and at the attic unit)

STEP 4 - Program your unit
You will need 2 IDs, both located on the back of the thermostat that plugs into the wall (see below) or on a piece of paper with the unit. IF THE PAPER IS MISSING, TAKE A PIC OF THIS BEFORE YOU INSTALL IT!



Now plug it in and set the date/time



Honeywell doesn't tell you this, but because my units had been tested out before (open box) they both had the little 'watch battery' in them.

VERY IMPORTANT -- REMOVE THE BATTERY FOR 60+ SECONDS PRIOR TO INSTALL!! YOU WILL NEVER GET YOUR WIFI TO WORK IF NOT!

I pulled my hair out until I figured this out. Once I pulled the battery and let them 'forget' themselves, the WiFi connection process went smoothly.

The first thing that happens after you're connected (just follow their little step-by-step) is it will spend the next 30 seconds connecting..then the next 5-10 minutes updating the software. Yes, the thermostats automatically get new firmware when you install them the first time.



That's pretty much it! Just register on their website and download the iOS or Android app and you're good to go!

My next update will be about the "WINK APP" compatibility since my wife is getting me the "WINK Starter kit" as a gift. You don't need to hook this into WINK to use it though.