RTH9580WF1005 Wiring Question

Old 03-12-14, 04:18 PM
Thread Starter
Join Date: May 2013
Posts: 4
Received 0 Votes on 0 Posts
RTH9580WF1005 Wiring Question

Replacing my 7 day Honeywell in my new condo with the Smart WiFi RTH9580WF1005 from Honeywell as well.

I tried connecting the cables using the provided instructions, but the unit appears not to be getting power. Attached is how the old thermostat was wired. There is no C wire, but the red was previously going to the RC. Also, I am not sure if Blue should go into W-O/B or into W2.

I appreciate the help!
Attached Images  
Old 03-12-14, 05:04 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 62,198
Received 1,531 Votes on 1,414 Posts
You're showing five colors there with no C connection. Your new WiFi thermostat requires a C connection.
Old 03-12-14, 05:33 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
Connect the blue wire to C on the new stat.
The TCON series labeled common B.
Old 03-13-14, 03:14 AM
Thread Starter
Join Date: May 2013
Posts: 4
Received 0 Votes on 0 Posts
Will do on the Blue to C. FYI, I also have Brown and Orange wires that are not stripped coming from the wall.

Old 04-07-14, 03:53 PM
Join Date: Mar 2013
Location: USA
Posts: 13
Received 0 Votes on 0 Posts
Hi, Iím just posting this in case you havenít gotten an answer on your orange and brown wires.

Heat pumps have a reversing valve which, in laymanís terms, switches the mode on your A/C unit to make it run backward to make heat in the winter. In 98% of heat pump systems, the orange wire would go to a terminal on the thermostat marked O. This terminal would be energized when the thermostat is calling for A/C. It will de-energize when the thermostat calls for heat. Your thermostat does not have the O terminal and the shielding is not stripped back on your orange wire so it hasnít been used. So Iím guessing you do not have a heat pump.

The brown wire could also be used for switching modes in a heat pump system. In the other 2% of the heat pump systems (mostly Rheem and Ruud systems) the brown or orange wire would be energized in the heating mode and de-energized in the cooling mode. Opposite of most other manufacturer setups, but there is nothing wrong with that because there is no standard.

The brown wire could also be used for a common wire for those thermstats that need one. Since your brown wire is not used, you most likely donít have a Rheem or Ruud heat pump, and the thermostat does not need to use it as a common. If you find the other end of the cable going from the thermostat to the furnace or A/C condenser, youíll probably see that the brown and orange wires are not connected at that end either. But thatís the most common uses of the orange and brown wires.
Old 04-08-14, 05:43 AM
Geochurchi's Avatar
Join Date: Nov 2012
Location: United States
Posts: 5,049
Received 91 Votes on 86 Posts
If you have a volt meter check between the red and blue to be sure you have 24 volts before you connect the blue wire to "C" terminal. That is a great Tstat I have 2 installed.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: