Another adding the C wire thread (to WiFi thermostat)

[Shai]

I hate to do this, but the other posts don't give me a clear answer, so here I am putting up this post.

So I have two wires connected to my thermostat. The voltmeter says I have 28V when I test the two wires and when the heater turns on, it doesnt show anything. I suppose that means I have a a Common and Hot wire? If so, can I jump the Common wire into the common slot on the Ecobee3 thermostat?
If so, how do I determine which wire is the Common and which one is the Hot?

Any help would be appreciated!

Thanks

 

[Stuff]

Two wires means there is no common. One is hot (Rh) and one is for heat call (W) .

Sometimes there are additional wires hidden in the wall. Easiest to check on the furnace end.

If you really only have two wires you can use this: http://www.fast-stat.net/