I'm trying to replace my old thermostat in my place with a new, preferably programmable thermostat. I have electric heat, and I do not have AC. My old Thermostat is a Chromalox model e200 I believe.

Now this is the trouble I'm having with it. Nothing is labeled on it. The wires and terminals have nothing on them so it makes switching out more difficult. The thermostat has 4 wires coming out of it, plus what looks to be a ground on the unit. It has 2 black wires and 2 red wires. I'm really stumped with this. Help please!