We are not familiar with geothermal as most people in our area have conventional AC systems. We are concerned about possible future costs and problems associated with having part of the system buried in ground. The geothermal system also seems to be a much more complicated/elaborate system than conventional units.

we have not yet performed a J-calc on the house to compare size of unit needed, cost of purchase and install, monthly operation costs, maintenance, and future replacement for different system types. But we do know the following specs for the house... 2500 SF living. R-23 in walls (rockwool spray and alum backed styrofoam). R-50+ spray in attic. Top plates and sole plates will be calked. alum radiant barrier backed OSB on roof to keep attic cool. super efficient vinyl windows and fiber doors.

gets into the upper 90s/low 100s during summer and down into 30s/40s during winter.

all of this taken into consideration, what do you recommend?
1. closed-loop WaterFurnace geothermal heat pump
2. air source heat pump
3. 16+ SEER conventional AC/furnace

If you plan to live in the home for 20 or more years I would seriously consider geothermal.

You have more of a cooling climate than heating which a heat pump even with heat strips would really work out great efficiency wise down there, but I am curious about the salinity of the air. How far south and how corrosive is the air is one other thing to consider. If you have to worry about the outside unit being in a corrosive environment I would really think geothermal.

There are so many things to consider and different ways to look at it. The outlook for electricity is increasingly higher rates to help cover the cost to make the coal plants cleaner and for more 'green' energy. The higher the electricity cost goes the better the geothermal will look.

If I was doing a new build and able to spin the cost of geothermal into the home without stretching other things I would head that way, even on a very energy efficient home.

I would compare the cost differential between 15+ seer HP and geothermal very closely and then look at the past 10 years of your electrical rates and past 5 years and do some projections for what the next 5-10 could be.

Either choice if installed properly will not be a losing proposition which is the best news!

I went back with a higher efficiency HP and let the geothermal go. I do not know if I will be in this home in 10 years and didn't see payback in 10 unless rates skyrocket which will probably be my luck.

I will over time invest in making this 3yr old home of swiss cheese more into a sealed up efficient unit and will see more savings than putting in geothermal and letting my conditioned air run out of like a door is open.

The relatively small extra cost of GT heat pumps compared to forced air heat pumps isn't enough to make or break that selection. However, the cost for the loop field (horizontal pit or wells) can be significantant as well as problematic - so there is risk in whatever cost estimate you get for the loop field. Finding qualified, experienced installers and maintainance people is very hard in some areas and that factor alone should weigh heavily in your decision. My HVAC contractor is 15 minutes from my home and had been doing GT for over 25 years. BUT there is only one other company in the area that I would trust to work on my system. If these guys go out of business, I will have to become my own HVAC service technician.

There are many factors that go into properly designing a GT systems and it is too impotrant of a function and much money to be risking especially when there may be better options suited for your geogrpahic location. If I lived in a high moisture/hot area like LA or FL, I would opt for the forced air approach and spend extra on spray foam insulation, good quality windows and doors, and proper ventilation (see Energy Recovery Vents).

I love my GT system and have had great results. But it isn't a slam dunk solution for everyone even with the tax credits.

1. countryboymo, we are not close enough to the Gulf of Mexico to worry about sality caused corrosion of outdoor equipment... though the air is usually very humid which may contribute to rust and whatnot
2. countryboymo, we do plan to live in this home for the next 50 years or more
3. Geothermal installs get a 30% rebate for the equipment and labor with no $$$ limit. All other installs receive a tax credit for 30% of the cost, up to $1,500 max per year. Many of the products in our home will qualify for the latter of these two programs -- fireplace, doors, windows, etc -- so if we don't go with geothermal then we basically get no tax incentives on our AC.
http://www.energy.gov/taxbreaks.htm
4. energy_rater_la, can you direct me to a link for the dept of natural resources program for new construction to get incentive dollars from them for efficient building? or do you have more info on the topic?
5. energy_rater_la, my builder took part in the construction of LA House on the LSU campus. I agree in that it is very informative place to visit.
6. We just finished the 4th preliminary phase of our house plans, and our builder's AC guy now has a copy of them. Hopefully he will do a j-load calc and provide us with some options for geo, air source pump, and conventional systems relatively soon. When I get the quotes, I will post them here.
7. we actually have a well on the property, but I hear that open loop geo systems are not a good idea. the minerals in well water supposedly cause buildup in the pipes and corrosion in the equipment. supposedly closed loop systems are the better alternative if they are installed properly but that brings about concerns with higher install prices and with having an experieced installer for the UG piping. we are also concerned with having part of the system burried in the ground (possibly having to dig up the yard due to complications is a little scary).

Hopefully I will have more info for you guys soon. in the meantime, keep the posts and info coming. THANKS!!!

I do have another question for you guys. If we decide to go with geothermal, a byproduct is hot water. what type of water heater would you use in combination with the geothermal unit?

BTW, the other tax benefits you mentioned are applicable only to upgrading existing homes, not to new construction.

The calc shows that we need 3.88 tons including ventilation air.

first, we looked at conventional units. Between 14 and 16 seer, there is a $2200 difference in equipment cost.
14 SEER = $10893 & 16 SEER = $13,100
b/c they buy so many 15 seer trane systems, they get the 15 seer system at the same price as a 14seer.
For our home, there is only a $90/year difference in operating cost between 15seer and 16seer. so the payback would be 6.7 years to go from 15 to 16 seer.
we would pick the 15 seer unit in this comparisson.

Air source heat pump in the same range isn't even worth looking at. it only saves an additional $10/month. Again, not a big jump from 15 seer conventional gas. however, the dealer did mention that we would probably have to install a fresh air system if we go with gas heat -- this is due to foam spray in our attic and the corners of our house. we may need to rethingk a few things if we go with gas.

this is where it gets interesting. we looked at geothermal.
1. the dealer sells all types of systems and manufactureres -- geothermal, air source heat pump, conventional ac... carrier, trane, frigidaire, water furnace... etc etc.
2. he assured me that he has hundreds of units in each system type installed in the local area.
3. there are two other geothermal companies in town, so should he and their whole company get hit by a bus tomorrow, there is still knowledgable geothermal service in the area.
4. I was initially interested in a closed loop system, but we do have a potable water well on site. a/c guy swears that in over 20 years he has not had a problem with open loop geothermal units on a potable water well in our area. local water quality is very high compared to other states where they have installed them. also says that the temperature in a closed loop varies b/c ground temp changes. says open loop is his preference due to consistent water temp from ground well.
5. top of the line Envision system from Water Furnace is $21,495 but the tax rebate is $6,449.
6. geothermal costs half as much to operate.
operating cost for the three units is as follows...
15 seer unit = $142/month = $1708 per year
16 seer unit = $134/month = $1610 per year
Geothermal = $ 61/month = $ 732 per year
7. we then put the units into a 6.5% interest loan scenario VS the monthly savings to calculate the investment payoff.
Pay off for geothermal VS 15 seer is 4.1 years.
Pay off for geothermal VS 16 seer is 3.8 years.
8. an installation tech showed us the geothermal loop piping. they use an iron to fusion weld the piping to the fittings. makes for a solid and thick joint.
9. hot water biproduct from geothermal can be used for hot water in our home.

all comments are welcome. please shoot holes in all of this. thanks again!!!