thermostat-c-wire
I read the following but my situation is slightly different: Wifi Thermostat to Reznor Garage Heater. No "C" wire connection on terminal strip He had an unused wire connected to W2.
I want to change the stat to one that requires a C wire. Installer used 18-3 and connected Red to R, Green to G & White to W1. Short of running new or more wire, do I have any other options?
Does the 24V have to come from the Reznor?
Thank you
Yes, tapping along with the red wire under the (C)OM is where it goes. If you'll notice, your (Y) is already double taped.
Note: the solution here is the querent's -- I'm simply writing it up in a CW answer to get this off our plate as the querent has not returned to migrate it from his question-edits to an answer himself.
SOLVED (01/04/15): I decided that the T terminal was exactly what I needed so gave it a try and everything is working perfectly. I also pulled in some 18-5 thermostat wire. Here is my setup, in case it might help someone else:
Furnace: Lennox G14Q3-60-13
Thermostat: Honeywell RTH6500WF
I've attached pictures of my connections.
Best Answer
Pick your poison
You have two options for solving this, but both of them are going to be a bit more inelegant than pulling a new thermostat cable. Either you can use a gizmo that "multiplexes" two signals over the same wire to free up the third wire for C-wire duty (there are several out there, with different installation instructions, so you'll need to follow the directions for what you purchase), or you can supply 24VAC from an additional class 2 transformer either plugged into a nearby receptacle or hardwired to the faceplate of a nearby junction box, removing the jumper between Rh and Rc then landing the new 24VAC source on Rc and C when you do this.