Command-Aire Thermostat

[snipes26]

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?

[vettech]

That would be your heat anticipator. It does exctly what it says and will cycle furnace at a differant rate. If incorrectly set it can make your furnace short cycle. Need to take and amp draw on your W wire while your furnace is running and set your heat anticipator accordingly. You may have to wrap a long jumper wire aroung your W wire 10 times to get a reading and then divide that by 10.