2-wire heater vs. 4-wire programmable tstat

[Harry Homeowner]

I have a two-wire heater (red and yellow wires) and I am trying to make it work with a four-wire programmable t-stat. Is this possible? I hooked the red and yellow wires, but nothing works. t-stat is ok - I had it on another application requiring four wires (both heating AND cooling).

thanks, Harry

[Jay11J]

It should work, what is the make and model of the thermostat?

[Harry Homeowner]

The thermostate is a Lux 500 with an Energy Star picture on the front of it. It worked in my main house with the gas heater and electric AC (4-wire system). I bought a new identical one to put in my shop that has a gas Modine 40,000 BTU heater with 2 wires instead of 4. The Gas Modine current analog t-stat clicks on (ignites the burner) and then kicks on the fan to circulate when the heater is warm. I did a swap from house to shop garage and both work in the house...? I have red hooked to red, and yellow hooked to yellow, and have left the other two color screws on the t-stat vacant.

[Jay11J]

For two wire system. you want a wire on R (power) and another wire on W(heat). The Y is for cool.