Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Help installing new thermostat


BeastSword's Avatar
Member

Join Date: Sep 2017
Posts: 2

09-11-17, 07:41 PM   #1 (permalink)  
Help installing new thermostat

I got a new Honeywell thermostat RTH8500D and having some issues connecting it up. I have a Gas Furnace as well and need help with wiring new thermostat, thanks for any assistance,
Image of original Wiring from Emerson Thermostat

The issue I'm having is the O/B or Black wire, there is no where to put that wire on the new thermostat which has the wiring diagram here:

Also here is a picture of the block on my furnace if that would help

 
Sponsored Links
Houston204's Avatar
Forum Topic Moderator

Join Date: Oct 2009
Posts: 6,825
TX

09-11-17, 08:58 PM   #2 (permalink)  
Do you have a model number for your thermostat, gas furnace or heat pump?

 
PJmax's Avatar
Group Moderator

Join Date: Oct 2012
Posts: 38,924
NJ

09-11-17, 09:20 PM   #3 (permalink)  
Welcome to the forums.

I think we need confirmation of wiring at furnace too.
No idea what black is doing there.

Can you confirm these colors on listed screw terminals ?
C = blue
G = green and white
R= black and red
W= white
Y = yellow

In looking further.... I see the black on R and the white on G coming in on a two wire thermostat cable. That means the black wire at the thermostat is not connected at the furnace.

Attached Images
     

~ Pete ~

 
BeastSword's Avatar
Member

Join Date: Sep 2017
Posts: 2

09-12-17, 10:45 PM   #4 (permalink)  
I ended up omitting the black O/B Wiring and everything seems to work perfectly, I think it may be used for a Air Conditioning but being in Canada I don't have A/C. Thx for the help

 
Search this Thread