[mikesibs]

I have a Weil Mclane Steam Boiler and Radiator System. I am replacing an OLD Honeywell "Electric Clock Thermostat". After removing the innards - I found the old unit was wired to 4 unmarked, uncoded wires.

It appears that the two wires on one side of the unit served to run AC power from a transformer in the basement to the CLOCK portion. The other two wires appear to be the normal wires for operation of the thermostat - however, I have no way to determine what wire is Red & what is White, and if, in fact, that is where I should be connecting them on the new thermostat (a honeywell 5/2 programmable).

My instinct is that the wire in the top right corner is the white, bottom right corner is the red.

Anyone know what I am talkin' about?

[hvac1000]

It appears that the two wires on one side of the unit served to run AC power from a transformer in the basement to the CLOCK portion

The two wires mentioned above will not be used and should be taped off. The transformer to power the clock in the basement should be disconnected from power.

You should have two wires left. Since there are only two wires the color makes no difference since you only need two wires for a heat only system. Hook them up to where the instructions say to hookup for a two wire heat system and make sure you have good batterys in the new thrmostat. If you want to dubble check the two wires that you are going to use are the correct ones then go down to the unit and disconnect the two wires you think will be for the thermostat. Temporary twist them together then go back up stairs and with a ohm meter see if the circuit is closed. If so those are your two wires to use for the new thermostat. OR you can take the two wires up stairs that are to be for the new thermostat and temporary hook the together. If they are the correct wires the boiler should come on.