My 20 yr old furnace crapped out. So,I'm gonna replace it and the AC unit as well.   I was wondering if anybody knew about heatpumps?   How well do they help to heat the house?  Are they worth the extra cost?   Thanks

With you being in Illinois...I would say do not get a heat pump.

Heat pumps are decent air conditioners, but not so great for heating. Better in a warmer climate than Illinois.

No, not where you live. They're pretty much useless below about 40 F. That's why the have a heat strip in them, for when it gets too cold outside for the heat pump cycle to work well. Even then, they usually only have a 5KW heat strip (in FL anyway) which doesn't do very much. Not only that, but I've had way more refrigerant leaks develop in heat pumps than in straight cool units; mostly in the evaporator coil. In MY opinion, (which is worth about what you paid for it) I theorize that this may be due to the expansion and contraction of the copper due to switching from heat to cool repeatedly. Again, this is just my own theory based on my personal experience. Some may disagree.

Are heat pumps used in single-family houses anywhere?  I thought they were only economical if they ran all day long, like in a retail or office building.  

Quoted: Are heat pumps used in single-family houses anywhere?  I thought they were only economical if they ran all day long, like in a retail or office building.

Yeah, they're very common in FL. Almost everyone has them. It's the same thing as running the A/C. You're just using valves to swap the evaporator and condenser. In cooling mode, you're removing the heat from your house and putting it outside; In heating mode, you're removing heat from the outside air and putting it into your house. That's why they don't work well at very low outside temperatures. The theory behind them is, it's more efficient and economical to run your compressor than to run resistance heaters. It works the same way in heat or cool, though. It cycles on and off as needed.

you dont want a heat pump where you live. they typical dont work past 38-40 degrees.
at that point the electric heat kicks in, and there goes the power bill.
they are great for places like central and north florida where it really doesnt get that cold.

I am an HVAC service tech who lives in North Texas. Heat pumps work great in Texas but not so well in the colder climates.