What terminals does it have exactly? RH or RC?

Most Residential Heating/Cooling Thermostats are for the five wire system.. RH, RC, W, Y, G,.

RH is the heating feed
RC is the cooling feed
W energizes the heating
Y energizes the contactor on you ac
G energizes the blower relay

Note if you also have W2, and Y2, it is a two stage stat, no need to use them if you only have a single stage system..

If using the five wires, the wires on RH, and RC, will go on R on the Furnace

If using only 4 wires, RH and RC need to be jumpered at the stat.. Keep in mind you can only do this if your furnace has R W Y G on board, Do not do this if using a seperate fan relay for your a/c..

[This message has been edited by jmcdonald (edited February 24, 2003).]

Sorry: Forgot to mention that you might be just using a Heat only Stat, In that case it does'nt matter where they go, you only have two wires, and it is 24 volt ac...