Gas and Oil Home Heating Furnaces - attic fan trouble

I just bought and moved into a home. I found that there is an attic fan, but I'm not sure how to make the thremostat work properly. There is a dial near the fan itself and another one about 10 ft away. When I adjust these, I can make the fan come on or off, but it either stays running or stays of. It doesn't cut on and off as I believe it should. Any suggestions? Thanks

Id say need more info here. You say two Tstat.? How are they wired up, are can you find out what does what Also dont forget when you set them they will run a long time when its hot . Mine runs from about 10:30 am till about 11:00pm. For now Id say you have to find out what turns what on up there with two tstat.;) ED

I'd guess that one is a speed controller and the other is a thermostat,...on the thermostat you will hear a click when it's adjusted in the grey area of the range....this will tell you the temp it is reading now...the one near the fan I believe is a speed controller with irrelivant numbers like 1-10, but the fan speed will increase or slow down as it is turned...the RPM controller will not have the clicking sound,... it's some kind of Rheostat I believe... in either case keep in mind it's line voltage!!!

It also is possible that one is a thermostat and the other is a humidistat and that they are wired in parallel so that the fan is turned on and off by either.

SOOOOOO Turn off the power to the fan. Take off the covers on the tstat's and find out just what you have up there and what each one is and how it is wired in. Then someone from here can help you.INFO INFO You might only want to use just one but what one?????;) ED