Honeywell Wifi Thermostat

Usain_VoltOctober 29, 2013

I've removed my old thermostat, which only had four wires. The new thermostat I purchased requires 5. I have no C wire to connect. I have tried all of the manufacturers suggestions, to no avail. Can I just connect the four wires and then run a new C wire from the thermostat to my furnace? Any help would be greatly appreciated. Cheers!

Thank you for reporting this comment. Undo
Ron Natalie

If you don't have a C wire (which usually is black but may not be, this is why you need to always carefully examine the OLD thermostat to see how it was wired) then this thermostat is NOT going to work. If the old thermostat DID work, then I suspect you don't have a compatible thermostat for your furnace.

Nothing will work with a standard low voltage thermostat without a C. All the other wires are referenced to that.

What kind of furnace is this?

You might do better over in the heating forum.

    Bookmark   October 30, 2013 at 7:16AM
Thank you for reporting this comment. Undo
dennisgli

Last year I replaced and rewired my thermostat. I needed the "C" wire to provide constant power to the new thermostat so I wouldn't have to worry about running down the backup battery. So I needed to run a new cable with three wires to replace the old one with two wires. I suspect that your now WiFi thermostat requires constant power.

So yes, you should be able to run a new cable with an additional wire to your furnace. BUT my ancient (c.1920?) control relay did not have a "C" terminal to connect to. So I ended up replacing it with a new Honeywell one for fifty bucks. So I would check to make sure that your control relay has a "C" terminal to connect to!

    Bookmark   November 1, 2013 at 1:27PM
Thank you for reporting this comment. Undo
Usain_Volt

Thank-you for the replies. I bought 18/2 thermostat wire from Lowes. Twrnty dollars for fifty feet. I only used the black white and ran it from my furnace to the thermostat. It works beautifully! Both AC and furnace operate exactly how they should. The hacks that were recommended may have actually worked? When I tried them I didn't remember to put the cover on the furnace back in place to engage power. Always doing things the hard way :-) I did learn some new things and definitely had fun doing it! Great forum! Cheers...

    Bookmark   November 1, 2013 at 6:40PM
Sign Up to comment
More Discussions
can homeowner so electrical work in his own home ? (above ground pool)
I live in Western ma and I'm having an Adobe ground...
growingadvice
Inspection Report
Had a gorgeous 1909 house inspected yesterday and don't...
cmae17
1 of 2 security light bulbs keep going out, do i need a new light?
I have a security light fixture in my carport that...
tlbean2004
Two fans on same circuit in different rooms, can't get wiring right
So here's the situation. I have two ceiling fan/lights...
jenfarino
Garage florescent light flickering - bulb or fixture problem?
I replaced the GE F40 RES garage lights with a GE F40...
bibbus 7b
Sponsored Products
Honeywell Flood Lights 180-Degree Outdoor Remington Bronze PIR 2 Step
$69.89 | Home Depot
Kaz - Honeywell QuietCareTM 17000 HEPA Air Cleaner - 3227-8012
$139.99 | Hayneedle
Kaz - Honeywell HHT-090 Permanent HEPA Type Tower Air Purifier - 2965-2633
$124.99 | Hayneedle
Kaz - Honeywell HFD-010 Quiet Clean HFD-010 Air Purifier - 2965-2658
$97.99 | Hayneedle
Kaz - Honeywell HHT-145 3-In-1 HEPACleanTM Germ Reducing Air Purifier With Odor
$209.98 | Hayneedle
Honeywell 1103 Molded Fire Chest - 1103
$62.98 | Hayneedle
Kaz - Honeywell 16200 HEPA Table Top Air Cleaner - 2964-2105
$59.99 | Hayneedle
Kaz - Honeywell 50250-S Life Time HEPATM Permanent Filter Air Purifier Multicolo
$179.00 | Hayneedle
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™