I have a command-aire old-tyme thermostat. It is a mercury controlled analog thermostat. My question is. What is the slide bar inside it? It has numbers on it like 1.2, .8, .7, .6, .5 and so on. What is that for? Does it have to do with how you make the difference or making up the difference between what the thermostat says ond what it really feels like to you? Will it make the unit run a little longer than it does now?