User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax)
Tony,
Generally the on/off switch on a thermostat is to keep the fan running
constantly whether the T-stat is calling for heat or not. In the off
position the heater plenum stat usually controls the fan.
Matt