I'm certainly not an expert but our heat pump never kept me warm enough. We switched to gas.

I don't know what kind of a heat pump you're considering (air to air?) or where you're located. But we went from one house with hot water baseboard heat (oil fired) to new construction with a geothermal heat pump and we love it! It's forced air, no baseboards, and very quiet. The electricity bill does get higher in the winter when the heat pump can't keep up with single digits outside (67 degrees inside) and we have to rely on backup electric heat, but on average our entire electric bill (heat, hot water, lights, everything) is $264 a month. We know people with oil or gas heat and hot water who spend that much on electricity alone for this size house (2700 sf)!

I have a gas furnace now, but when it dies I will switch to a heat pump. I will get a geo thermal one if I can afford it. If not, I'll at least get a hybrid heat pump. The hybrid heat pumps use gas heat as the back-up heat instead of the electric heat strips. Heat pumps have come a LONG way from the way they used to be.

You'll need to keep the gas furnace as a backup. Once the temps drop into the low 40's a heat pump is pretty useless. As an air conditioner they're great.

You'll need a thermostat that controls both the HP & furnace and can be programmed to switch from the HP to the furnace as needed.

Our last home was heated with gas and regular central air. Gas water heater too. We were happy with it, but never knew anything different. Our bills were usually a little less than our neighbors, but then we are a conservitive family. It was 1800 square feet. 650 of that being lower lever of a split entry. In other words like a walk out front at the garage side.
We now have an all electric home. We didn't have the choice of natural gas and didn't want propane. From October one to April one we get a 38% discount because of our heat pumps from the local electric company. We also had large rebates from the power company when we purchased our heat pumps.
We have two electric furnices and two heat pumps. A smaller set heats and cools the second level and the larger set heats and cools the main level and the walk out basement. We also have an electric heater/air-conditioner combo for our 644 square foot garage. That ofcourse isn't run on a daily basis, but sure is nice when you want to do something in the garage on a hot or cold day.
Anyway, quite often we have spent less to heat and cool our 4500 square foot home (that doesn't include the garage) than we did with our gas furnace at our last 1800 square foot home.
Granted part of the savings could be because we built this home with energy conservation in mind. All exterior walls are built with two by six lumber and insulated with icynene. All windows are double pained filled with argon gas and the attic is insulated with more (deeper) than recommended cellulose. http://www.cellulose.org/green.html Both products are not only very efficient, but very green.
I hope this helps. I know I said more than you asked, but I'm sure a lot of what makes our home toasty warm and super cool is the combination of all the above.
~Becky

Here is a link that might be useful: Icynene

Ditto everything Annz said. We live in the South and have had heat pumps for a long time. New construction 3yrs ago, have them again. We have always had a piggyback gas furnaces that the system kicks over to when it gets below 40 (they say below freezing, but 40 get too cold for me).

We live in PA and HAD a heat pump and just replaced the whole thing with a regular furnace and AC. Heat pumps are great in the south I was told or if you are dealing with oil, etc. but for a cold winter like we get and electric rate caps coming off in 2010 we just did away with a heat pump.

I think alot of it depends on you and where you are. We are in the south, have fairly mild temps and a heat pump is wonderful for us. Hubby and I are also pretty warm natured.

I have never cared for gas heat. To me it can be too warm and it is also drying. The price of heating with gas has also risen.

We have a heat pump - and no gas back-up. On the rare occasion the house feels chilly, we simply use the fireplace as a bit of additional heat. Our electric bills are not bad, we usually have a couple of summer months that are higher than our winter bills.

We have 3 heat pumps, one for the main house, one for our very large garage (4 car plus hobby/workspace) and a small unit for our sunroom (this was a screened - in porch at first and not heated/cooled).

I should point out that while we personally do not need back-up heat, our house is super insulated. We also have a nice warm basement and I do think that helps the main floor.

In reading some of the other comments about heat pumps I'm even more sure you have to have the right home to go with them. We live in eastern Nebraska and get pretty cold, but do just fine with ours.

I agree with what most everyone else has said. I'm in the south and a heat pump isn't enough for me part of the winter. We supplement with a gas fireplace in the evenings to keep the main part of the house warmer and use an electric blanket at night.

My experience with the heat pumps was that the A/C was great but the heat was lukewarm air, not hot enough (like a furnace would have) to bring the house to a comfy level very rapidly at certain times of the day, specially after sundown. There is a bypass button to go straight to the back up heating source.

I guess one would have to calculate the diff in price between the 2 machines ,
basically the heat pump gives you free heating for a few hours of the day, and if you managed to not switch to your alternative heating source too often, your savings would pay off the diff in price between furnace only and heat pump, it was not worth it for us because we live in a cold climate so I would bypass the heat pump constantly between nov and april.

Another vote for keeping the gas back up! I have lived in the north and south, have lived with only a heat pump in a couple of places. In the south it was fine, we would have a cold couple of days where the heat pump didn't quite keep up, but it was over soon. In the north, there were stretches of 2-3 weeks at a time where I would have done anything to be able to just get warm for a couple of hours. After 2 days, the building (with the concrete slab floor) would cool and I remember wanting to go out to eat at a certain resaurant because it was always toasty warm....

Needless to say, when out ac went out and my husband talked about a heat pump, I let him do it, provided we kept the gas for winter back up. We do save a fair amount in the "in between" weather months, but the gas takes over in winter. You can get a programmable thermostat on the gas that is kicks in when it is a certain temp outside. Heaven!

Heat pump here, not by choice. Air conditioning works well - cools the house quickly. Heat doesn't get warm enough, no matter how high I set the thermostat.

We also use a 2 zone heating system on our second floor to warm the rooms quickly. If only I had access to natural gas!

If your furnace is in good shape keep it and add a heat pump. we have both. The heat pump does the AC and also the heating until the temp drops down to a certain level.....I can't remember what my husband has it set at. After the outside temp drops below that mark then the gas furnace takes over.

Whether a heat pump makes sense for you all depends on your circumstances.

IMHO, heat pumps blow cold air on you. They heat the room well enough, but because the air they blow out is not all that much warmer than the room temp (like you would get with a oil or gas furnace) the air that comes out feels chilly rather than warm. Compare to wind chill factor.

If you get one, direct the vents away from any area you will sit.

-Lena

Yes, the heat pumps (we have geo) don't use superheated air so I think there is less chance of drying things out. We have electric backup but I would keep your gas furnace if it's in good shape. One thing our installer told us was to keep the temp set pretty constant all the time. If we programmed the thermostat to go down to say 60 at night downstairs then want to come back up to 68 at 6am so when we make coffee the kitchen is warm, the electric heat would kick in and it would cost a ton. We've experimented since system came with programmable thermostats (why?) and seems like we can drop it, then raise it about 2 degrees at a time without kicking in backup heat. But we know lots of people who just leave it set at 68 in the winter and 75 in the summer.