Connecting batteryless thermostat with a "C" (fifth) terminal to my furnace
Thank you MyDad'sGirl77. Though I never thought of my problem as a plumbing problem, your response was most helpful, and it spawns new questions in my mind. My transformer leads of course are connected somehow to those four (R,G,W,Y) terminals on my furnace. My multimeter shows 24VAC between R and each of G,W, & Y at my furnace. There is no voltage reading between any of the other terminals. I'm guessing R is the hot transformer output. If this is so, why could I not jump from R to C at my thermostat? The thermostat installation literature says "C" should be connected to 24VAC. If not a jump from R, how about a jump from Y?