Where to connect new C wire from Thermostat ..? Pic.

Jul 28th, 2015 7:48 pm

#1

Mastero [OP]: Jr. Member; Apr 6, 2015; 199 posts; 141 upvotes; SW Ontario

Jul 28th, 2015 7:48 pm

Where to connect new C wire from Thermostat ..? Pic.

I am buying new Honeywell Wifi smart Thermostat to replace 17 year old thermostat which has 4 wires .
Instead of going diffrent options available to substitute with Gwire and stuff ,I can pull new wire .
On the circuit board in furnace - in the picture I have HRV and thermostat wiring on it .where will this new C wire go in the circuit board slot ?

[IMG]http://imagizer.imageshack.us/v2/280x20 ... VMM0cq.jpg[/IMG]

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Jul 28th, 2015 8:21 pm

#2

schade: Deal Addict; Dec 17, 2007; 2619 posts; 1594 upvotes; Alliston, ON

Jul 28th, 2015 8:21 pm

24v COM

Jul 28th, 2015 8:31 pm

#3

Mastero [OP]: Jr. Member; Apr 6, 2015; 199 posts; 141 upvotes; SW Ontario

Jul 28th, 2015 8:31 pm

schade wrote: ↑24v COM

White wire from HRV unit is already in -putting a new one on top of it won't do any damage right ....?

+1

Jul 28th, 2015 9:47 pm

#4

sprdave: Deal Addict; Mar 28, 2008; 1639 posts; 583 upvotes; ON

Jul 28th, 2015 9:47 pm

Mastero wrote: ↑White wire from HRV unit is already in -putting a new one on top of it won't do any damage right ....?

That's your AC wire, and yes it's the COM along with the other white, but put it under the other side of the screw.

Jul 29th, 2015 7:44 pm

#5

Mastero [OP]: Jr. Member; Apr 6, 2015; 199 posts; 141 upvotes; SW Ontario

Jul 29th, 2015 7:44 pm

sprdave wrote: ↑That's your AC wire, and yes it's the COM along with the other white, but put it under the other side of the screw.

Instead of fishing new wire and messing with circuit board on furnace - can I take a wire from the one which is powering my HRV controller ,which in next to my thermostat ..? Tx

Jul 29th, 2015 7:57 pm

#6

sprdave: Deal Addict; Mar 28, 2008; 1639 posts; 583 upvotes; ON

Jul 29th, 2015 7:57 pm

Mastero wrote: ↑Instead of fishing new wire and messing with circuit board on furnace - can I take a wire from the one which is powering my HRV controller ,which in next to my thermostat ..? Tx

Umm where does the cable from the HRV controller go to? Doesn't necessarily have a spare wire either, and really shouldn't mix the two systems anyway...

edit: as in where is the HRV unit in comparison to the furnace

Aug 1st, 2015 4:50 pm

#7

Mastero [OP]: Jr. Member; Apr 6, 2015; 199 posts; 141 upvotes; SW Ontario

Aug 1st, 2015 4:50 pm

Ok so I have all the hardware now for running a new line - HD guy gave 14 gauge single wire instead of 18/2,3 to run from 24 v com to thermostat C point . Would 14 G be a issue here ..? Tx

Aug 1st, 2015 5:22 pm

#8

schade: Deal Addict; Dec 17, 2007; 2619 posts; 1594 upvotes; Alliston, ON

Aug 1st, 2015 5:22 pm

14g would be fine, although overkill. If you're running a new wire, i'd pull a 18/2 or 18/4 wire in. Down the road if you ever wanted to add another device and needed more wires to your thermostat, your all set.

Aug 1st, 2015 7:27 pm

#9

Mastero [OP]: Jr. Member; Apr 6, 2015; 199 posts; 141 upvotes; SW Ontario

Aug 1st, 2015 7:27 pm

Cannot fish the wire - struggled for couple of hours too tight .Given Up
Back to option 2 as per Honeywell take out G green wire and put in 24 com and then put a jumper between G and Y .thus loosing manual fan .question is my y terminal already has red and blue wire on it - should I put jumper on it too -won't it be putting more load on it ?
Finally any suggestion on other better thermostat with 4 wires without all this . Tx
[IMG]http://imagizer.imageshack.us/v2/150x10 ... KT9j2K.jpg[/IMG]

Aug 2nd, 2015 12:15 am

#10

foodyforlife: Deal Addict; Jan 6, 2015; 2860 posts; 783 upvotes; Toronto, ON

Aug 2nd, 2015 12:15 am

Buy the Ecobee 3 and you won't have this problem. I didn't have a c wire and the Ecobee came with a lot to get power to the thermostat