Originally Posted by pawoSD

Incorrect. An old furnace is approximately 35% or more LESS efficient than a modern unit, and brings with it safety risks such as a cracked old heat exchanger. In a single cold winter, you could spend over $1000 more heating with an old piece of junk than with a new furnace depending on the size of house. My high efficiency unit is in its 5th season and all I've had to do is air filters and replaced a piece of plastic tubing that was leaking water. VS an old unit it has paid for itself twice over just in the fuel savings at this point. The control boards are not that unreliable, mine even has it right in the box with the burners and draft blower and its been just fine. Higher end furnaces put the electronics in their own closed compartment so they are even more protected.

DIY on the HE units isn't even that hard, just need to know a little more about basic electronics. They are no more sophisticated than the auto-klima boards on our old MB's. You can buy a decent brand new HE furnace for less than $1700 that will give 15+ years of service....its a no brainer.