Hello,
I recently purchased a Totaline Thermostat P/N P374-1800
My old on has a 4 wire system. Propane(Gas) and single heat,and single cooling .

The wire colors are Green, yello,white and red. I wired the new one, red-R,green-G, Yellow-Y1 and white -W1.
I did not use C (+24vac common) and
I did not use W2 (2nd stage heat ciruit)
Now when I instaled face cover, Nothing shows in display.
NO What? I could sure use some help...
Thanks
Bob

Does this t-stat have battries? Odds are pobally not. You will need to get a coommon wire to this stat to work. From common on the unit to c on the stat. Or you can get a different stat that says battery operated not 24 volt operated

Yep,, and cross your fingers,if you didn`t kill the breaker to the furnace ,hope that you didn`t blow the transformer,, it happens a lot

You need the 24v common wire to make it work. That's a two stage heat two stage cool thermostat be sure to set it up for a/c and not hp.