I have a WESCO uem 20kw electric furnace, about 25 yrs old, It had a single temp stat first then a setback stat was installed, with a box added to the furnace controls, the set back stat failed after a few years so i put the original single temp stat back and it worked for years now, a while back the furnace began to run with the heat on even though we turned tha temp down, the only way to stop it was to turn the breakers off. that seamed to solve the problem but the furnace would run wild once or twice every 6 months or so. Now its started to run without stoping the heat and the only way to stop it is to turn the breakers off. I understand that WESCO hasnt made this furnace for years now. what do you recomend. is the stat bad and can i replace it with another manufacturers stat? I have been planing to replace the old furnace this summer when all we run is the fan,

It could be in the stat, and it could be a sticking relay in the unit. It might be time to call in the pros, ask family and friends for a trust worhthy company referal