Running new line for adding C wire - advice


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Old 05-05-17, 06:57 PM
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Running new line for adding C wire - advice

I'm looking to re-run my thermostat wire as I currently only have 4 wires and I want to have a C wire available as I'm looking to install a smart thermostat in the future, maybe a Nest or Ecobee.

Current:
Thermostat: White Rodgers 1F80-261
Furnace: Tempstar FBF075B12G1
AC Compressor: Tempstar Tca030aka4

Current wiring layout
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I remember when we first moved in, I didn't think the fan was wired correctly, because turning the fan on manually at the thermostat didn't actually turn it on. I tried moving the green wire to G terminal on the furnace and then the fan worked, but AC didn't function correctly, although at this point I don't remember if it was that the fan didn't turn on when cooling, or if the compressor didn't power on. I put things back and the fan does work on manual, but I have to wait the 30 second timeout before the fan kicks in, since it is wired to Y on the furnace.

When I run a new cable bundle with 5 wires, how do I wire the C wire from the thermostat to the furnace? Do I connect it to the same splice with the red wire from the compressor that goes to C on the furnace, so I have 3 wires connected there?

Side question: Is it common to staple thermostat wire to studs in the walls, or are chances it is just free? I have a fish tape if I need to run it manually, but would prefer to not. Temps are mild for me for the next few days, so if I get into trouble, I could manage while I get things figured out.
 
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Old 05-05-17, 07:11 PM
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Welcome to the forums.

You're right.... it's not wired correctly.

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Run more wires than you need 6-7 wires is ok. Future spares.
Usually the cable is stapled in the wall.

You connect your new C wire to C on the furnace board. You will have two wires there..... one from the stat and one to the condensor. I don't see a third wire.
 

Last edited by PJmax; 05-05-17 at 09:04 PM.
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Old 05-05-17, 07:35 PM
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I can't see your attachment, says it is invalid.

I already have a small spool of thermostat wire with 5 wires in it from another project I was going to use to just replace everything as long as I can get it up through the wall. If the original wire is stapled it, then I'll have to fish the new wire up, which makes it a little less risky that I end up in a situation where I have no wire I suppose, but a more difficult run.
 
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Old 05-05-17, 07:43 PM
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I was able to view the picture.
I will try posting it for you.
PJ's diagram...
 
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Old 05-05-17, 07:47 PM
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Thanks, I can see the diagram now. Makes sense to me. I'll get the wire ran and give an update.
 
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Old 05-05-17, 09:06 PM
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Thanks Carlos..... the board ate my picture.
 
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Old 05-08-17, 12:22 PM
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Thank you for your help. I successfully ran the new wire. I had to drill a 1 inch hole in the wall to be able to grab the new wire through and as expected, the original wire was stapled to the studs so I couldn't pull through it.

I updated how it was wired and now the fan turns on immediately, AC and heat works as expected. I have a new Ecobee 3 on the way now that I'm all set!

Here is my updated wiring.
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Old 05-08-17, 12:25 PM
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Good job.... you're all set.
 
 

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