Any smart thermostat wiring gurus on here? I need help

What kind of heat pump, if it's a mini split that won't work.

I'm not a HVAC guy but I do my own shit, master electrician.

Is your unit forced air? I had the same issue where I had a blue wire that was not connected to anything so I used it as my C wire. I did have to go to my HVAC unit and connect the blue wire too (unfortunately I forget exactly which terminal i connected it to) I believe i just tied in the blue wire to my 12/24 volt wire at the HVAC unit itself and it worked. This video helped.



Last Edited by Dr Mantis Toboggan on 07/23/2017 03:35 PM

All I know so far is its a trane. My folks lost the manual for it but if you need the model I'll crawl up there and get it. I had it seemingly wired correctly but it keeps blowing hot air instead of cool. It's something with the o, w, c wires not all being right. I think

My blue wire was the O wire in the old thermostat. So I have the blue in the World O/B slot but then I'm not sure what to do with the white wire. I put it in C and W2 and neither works. It's a heat pump 99% sure

What model Thermostat is it? I had to do some online research when I connected mine because the manual itself was useless.

This video is pretty helpful. From what I gather, G will go into C on the new thermostat. (skip to 2:45)



[link to www.youtube.com (secure)]

Do you have a blue wire?

Which Honeywell model did you buy?

Ecobee has an option for those without a C wire.

You should try to go to real DIY websites for help, but the pro's don't help DIY'er very often, and it is real expensive to fuck up your system listening to advice not professional.

Call an HVAC company for help, or buy a thermostat like the Ecobee that has the option for those without a blue C wire.

Don't waste your money on a HVAC clown. Thermostat wiring is easy shit that doesn't require you to spend 100 dollars PLUS on some asshole to come out for 10 minutes to connect it. Very easy DIY project.

Also, when I did mine, I pulled the wiring loom out of the wall and noticed there was a BLUE wire that was not connected to my old thermostat and was just tucked into the wall. This is very common apparently so make sure that there isn't any wiring hiding in the wall. If there is, that most likely means it is at the HVAC system itself and is not connected. Open it up and connect it to the corresponding connector on the terminals.

I've tried the G to C and any other combination I can think of. It works and keeps blowing hot air. My problem is my old thermostat letters don't exactly line up because of this damn O wire

I think I need a transformer extra wire I just wanted to make a little more sure first lol

You must be talking about a ducted system, my advice. Rip all that shit out and go with a ductless system.

I just installed my second one in my home yesterday, so much more efficient and economical to operate.

If you're handy at all you can do the whole install yourself and save thousands.

Well that stinks.. I would still try to look for the extra wiring tucked in the wall first. Im the type of person to try everything possible before calling one of those overpriced assholes to do the work. As I said, take alittle time out and get the model number to the thermostat and do a google search for some tips and what not. I did that and after a few hours I got it working. Good luck!

They sell an item for such a problem. Just call your local hvac supply house and explain your situation they'll either know or not. Other wise you need to pull new wire, I recommend 8/18g wire so you'll have extra wire if one ever breaks

He has a heat pump, the video you posted was for conventional furnace.

There probably is a DIY fix, and it would be connecting a blue C wire to the furnace.

The o/b wire is for a heat pump.

Found this OP...


5 Wire Honeywell Thermostat Wiring

Some programmable thermostats (e.g. Honeywell Prestige wiring requirements) need a minimum of 5 wires, and maybe more depending on what features you want to operate (humidifier, etc). The additional 5th wire will be for common; providing stepped down power from a transformer.

G – Fan (green wire)
R – 24 VAC / R and Rc (red wire)
C – 24 VAC Common (color can vary per manufacturer – may be blue, purple, brown. etc.)
Y – Compressor / air conditioner (yellow wire)
W – Heat (white wire)

[link to diyhousehelp.com]

Judging by this, the Orange would be used in place of the C?

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The connections on the T-Stat are what you listed.

What color and Count of wires are in the wall.

On the T-stat there should be a jumper between the r/rh.

In the Install Manual it should have a section for connecting different types of Equipment.

Your Heat pump has Specific connections to USE.

Typically there is a wiring schematic on the back of the Electrical Cover on the Unit that Shows the connection for thermostat.

Some Heat pumps use R, W, Y, and G as a Minimum with a Battery Powered T-Stat.

Others use R, C, W, O/B and G for Non Battery Powered T-Stats.

Digital T-Stats have multiple options for Equipment that Must be Programed in the T-Stat.

It's NOT Rocket Science, Look at the wiring schematic on the back of the Electrical Cover than Look at the Install Manual to find the Proper Connections/Correct Programming to USE.

Hope this Helps.

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