No Common Wire to Thermostat

[SavvyCat]

Okay, guys, you're going to love this one. I have acquired free of charge in exchange for review the new Cor thermostat from Carrier. : My inner nerd is giddy with excitement, because I didn't even know there were wifi stats until the house being built next to my cousin had two units show up as networks in my iPhone (and yes, I did try to tamper with them).

It was good enough that I got my hands on a 5-1-1 programmable for free not long before I bought my house (anticipation). The comment from my real estate agent about the existing round gold one was, "I have never seen a vintage merc in such great condition!" Anyway, "vintage" was tossed in a drawer and I put up the new White & Rogers, but now the Cor is on its way.

Trying to get a head start on what it will take to put it up and get it running, I downloaded the documents from the Carrier site. Uh oh! After seeing a note of warning about the need for a C wire, I dashed to my thermostat and found that, alas, there wasn't one.

Am I nuts for thinking I *might* be able to just pulled new 5-wire cable from point to point? Are there any sneaking HVAC genius workarounds that would solve the issue without doing that? I really, really, really want this thermostat. Apparently there are a couple that don't require C, but those aren't free to me. (I bet you can guess how my review will begin.)

SC

 

[user 4883]

Most likely the existing wires are staple to a stud inside the wall so little chance you can use the existing wire to pull a new one.
If your lucky try stripping back some more insulation jacket and see if a spare wire was snipped back because they didn't need the common when originally installed.

 

[SavvyCat]

You, sir, are a genius. : That's exactly what they did. Now, before I crawl up to see if it's connected on the air handler/furnace, what are the chances it already is connected if they didn't connect it at the thermostat?

 

[SavvyCat]

Done! Now people can hack my HVAC.

FYI, I got the thermostat free through a program I'm in with Home Depot. I'm supposed to review it. All I can say is it was much more difficult than it should have been in my case, but I'm no quitter!

I peeled the sleeve, as suggested, and it turned out the original installers weren't using it and snipped it (blue) off. I attached it all and turned the power back on... nothing. That meant the Common was either damaged or not attached at the other end. So I pulled out my meager 6-foot ladder and peered into my attic space. The furnace is right there, thank goodness, but I can't get to it without stepping onto the very top of the ladder, and I ain't gonna do that. Not when there's no one below to catch me.

Luckily, in the same round of freebies where I got my thermostat, I also got this collapsible (!) extension ladder. While compact and portable, that dude is heavy! I thought I might just sell it and make something up for the review because I'm never going to use it!

Never say never.

So, I opened up that box and hauled it out, figured out how it worked, and got up to the space with my flashlight and screwdriver. It spooks me enough transitioning to the attic from the ladder, but I find that one of the panel bolts is slotted and the other hex, dang it. So I gingerly climb back out of the attic to fetch a wrench, and repeat the process. I opened the panel and :::gasp::: the Common (blue) is connected. But they're using wire from two cables here, so I trace the one from the thermostat area and it has extra wires wrapped around it, but I don't see blue. Aha! It's hidden underneath. Whew!

So I added it to the C terminal, closed up the panel with TWO slotted bolts (there's a whole bunch of screws scattered up there), and came back down.

Of course I had to figure out how to collapse the collapsible ladder and almost lost fingers in the process. I digress, but I'll have to write an extra caution about that.

Tada!

 

[nealtw]

Good for you, job well done. That ladder is the one you never want to use but handy enough when you need one, price was right keep it.

 

[SavvyCat]

Yeah, it's an odd contraption I'm not sure about. I get nag reminders about reviews, but I'm going to have to mess with it a few more times before I can speak intelligently about it. I'm sure few, if any, people take their duty seriously in this program. But I know how much I rely on reviews, and anything you see from SavvyCat anywhere is going to be well considered. (I use the same name all over the place.)