My home is equipped with 220 V window unit airconditioners, and gas space heaters. The former owner had rigged a wall mounted thermostat for the kitchen air conditioner and space heater using a 24 volt transformer and a separate relay. The 220 V outlet that the air conditioner plugs into is wired into the relay. The 24 volt transformer gets its power from a nearby 110 V outlet. He had three wires coming into the thermostat (red, blue and white). The blue and white came from the relay to the transformer and on to the thermostat. The red wire came to the thermostat from the gas space heater (it was hooked to a spark apparatus. I disconnected the red wire from the heater because I didn't trust the setup. However since it didn't affect the window unit, I did not disconnect the red wire from it's terminal on the thermostat. Now the problem. I had to replace some sheetrock where the thermostat was mounted. Like a dunce I did not write down which wire was at what terminal. The wiring at the relay has not been touched. The wiring at the 24V transformer was disconnected, but I wrote their positions down, so I am 99.99% sure that it is the same as it was (the window unit worked without the red wire being connected to anything). I am assuming that since it was already disconnected, the red wire that was connected to the space heater spark apparatus, isn't needed. So I have a blue and a white wire to hook up to 2 of three terminals. This whole set-up is a poor man's energy saving switch. When the thermostat kicks off the power is shut off to the 220V outlet that powers the window unit from the relay. My problem is that I don't want to burn out the transformer while switching wires at the terminals to see what will make the thermostat trigger the relay.

Is the relay marked Pos/Neg? If it is then you can check for matching terminals at the thermostat. Then hook the connecting wires to the correct poles.

Can you show a picture of the relay terminals? It's no doube a double pole relay.