Where do you live and what's your climate zone? How large will your house be and how many occupied levels? And how would you desire to "marry" future systems with your current one?

Pretty hard to respond until we know the answers.

I live in Northwestern Pennsylvania and the climate zone here is 5. The house will end up being about 3700sf including an unfinished basement, but eventually we may do something with that. If I do go the geothermal route, I will still be using wood to heat my garage. I'm not sure if it's feasible or even plausible to use both systems, but it would be nice to perhaps have the wood as a backup someday.

Here's a site with the prescriptive insulation requirements for each county in Pennsylvania: http://energycode.pnl.gov/EnergyCodeReqs/?state=Pennsylvania

I'm not an expert on HVAC systems, but I live in southeastern PA, (Chadds Ford), and have two geothermal heat pumps, zoned for my 4-level colonial house (2 levels per heat pump).

Heat pumps work fine in my area where only electricity is available as a power source. They require back-up heat sources for truly cold, low temperature periods when the heat pump is no longer very efficient in producing heat, and a backup generator when power is lost due to storms and downed power lines. Fortunately, these climatic periods are rare and short-lived (except for this winter!).

If your part of the state has extended and consistent periods of low temperatures you should do some comparative analysis of heat pumps versus other types of HVAC equipment.

I don't see a way that your garage heating, using a wood furnace, can be linked to your house system, but you may be able to use the heat pump(s) for the house for the space above your garage with proper planning and design (assuming house and garage will be connected).

You may want to take you question to heating and air conditioning forum for additional discussion. Good luck!

Deleted double post.

This post was edited by virgilcarter on Mon, Feb 10, 14 at 12:17

Not an expert here...this is only a comment regarding our own geothermal unit. We live in northern Wisconsin, and its been brutally cold this winter. One day we had -79 wind chill. Our house is 5200 sq ft finished. We've been using our geo unit for 3 winters, and our backup gas furnace has never come on. DH checks it now and then just to make sure it's still working. We are extremely happy with our geo, especially since LP recently went from 1.70 to 4.50. After hearing of some of the outages in PA, a backup generator would certainly be a great thing to have.

We built our new home last year and installed a closed loop geothermal system. We received a check for today from our electric company for $3,500.00 for installing geo and will use the Federal Tax Credit when filing our taxes for 2013.
We are very happy with our geo system and the numbers worked for us to install it.

I envy all you with geothermal options that aren't a small fortune to put in (around here, you are looking at 40k out of pocket).

But, for the OP--check out the HVAC forum. You'll get many HVAC professionals there with their input with regard to "marrying" the systems, etc.

Go to greenbuidlingtalk.com They have a forum there on GEO. Allot of experts there on geo.

We just built a new home with geothermal. It was costly but we absolutely love the system. Nice even heat and no oil bill! We don't have natural gas available to us so it was either oil, propane or geothermal. We're so glad we went this route!

Our geothermal system works off water from our well. We bought an existing house, and the owner "never had any problems". Running the well pump as much as our colder than normal winter has been too much for it. We have replaced the pump with a higher horsepower Feb, 2013.
We have had it stop working 3 times and now have to replace it...again.

My theory is: A well pump is not meant to run so long at a time. Logic tells me that we are using twice as much electricity heating and cooling this way because we have to also run the well pump AND the heating unit. If we had access to city water, I can't even imagine what the water bill would be using our system.

If you are thinking about using geothermal and using water instead of underground air, don't do it.

If you are thinking about using geothermal and using water instead of underground air, don't do it.

Using water works fine, but you need a separate water supply system. NC law is that you cannot use the same well for drinking and the geothermal.

We've had geothermal for going on 4 years and are very happy with it. We use wood stove too and haven't had to use emergency heat ever. When looking at geothermal, remember if you use it with an air system, it is your a/c too. We too are in zone 5.

Thanks for all the insight. Geothermal is definitely appealing to me, especially right now with the credits that are still in effect. I just feel as though I've wasted money with buying and installing a wood burner, but such is life.