The house is 3600 SF (2900 down + 1 big bonus room upstairs). We installed a 5-ton geothermal system, but to keep from getting a 6-ton we chose to install high R-value wet foam insulation, low e windows, etc. Be sure to get a heat gain / loss analysis to correctly compute load / sizing calculations using the ACCA Manual J. After much research, we selected the WaterFurnace Envision series 30EER, 5 COP with 4 dampered zones, 6 return air vents. The system is variable speed and has 4 closed vertical wells that go 250' down into the earth. The unit also will provide about 75% of our hot water by redirecting heated water (byproduct of geo process) to the hot water tank. Our heating bills so far during construction have been very low and I am excited to see how the unit operates in the hot Oklahoma summers.

If you'd like to see some pictures of the unit, check out our home website. Week 6 shows the ductwork install (below slab); week 18 shows the drilling of the wells, and week 19 shows the geothermal unit. Good luck.

http://www.gelmac.com/newhome.asp

Thank you, thank you! I really appreciate the information and the advice. Funny how I've suddenly become so enthralled with furnaces and foam insulation. I hope you'll post how the unit keeps up with our balmy summers.

And I couldn't help but peek at your photo progression. Your house is gorgeous. I particularly love the dramatic red entry and your beautiful woodwork. It's all lovely.

We also have geothermal. We went with closed loop, horozontal system. We trenched 400 feet out on our property (we had the room, so why not?). You can see some of the trenching on my blog. Just click on the tag for geothermal and you can bring up the rest of the blog entries about geothermal.

Here is a link that might be useful: Geothermal blog entry #1

nuther

I just finished a home with a 12 ton geothermal system. cost isn't prohbitive - but there is a higher initial cost when comparing to other traditional hvac systems so you need to stay in the home for a while to break even.

if you compare costs for forced air systems - the duct work is the about the same cost. the GT heat pumps are a more than traditional heat pumps or the combination of gas/AC unit for the same BTU output. There are also additional plumbing costs iside the house - a pump system and PVC pipes that run over to your GT heat pumps. For my twelve ton system (2 x 3 ton and 1 x 6 ton) the delta cost for the GT was $15,000 for parts and labor when compared to LP gas heat and AC compressors providing the same BTU output.

By far the largest delta cost for us was for the loop system. And these costs vary so much by site and specific implementation. I did a horizontal system and digging a 120' x 48' x 6' pit cost a lot more than what we had expected. Doing wells (12 wells at 100' each) would have been about the same cost. We hit a lot of boulders and we had issues moving all that dirt around.

The system works great - is very quiet and ecconomical. We used cellulose insulation in the walls (2x6 studs) and R38 cellulose in the attic. We used some foam in joist cavities and other places where the cellulose would not stick well. All foam would have been better but we found the cost too high and the payback not that great when comparing the cost of the cellulose with the GT system.

Make sure that they seal your house - caulk every nook and cranny on the inside to make sure you keep the air infiltration to a minimum. If you do that, then a cellulose package with good windows & doors will work well with the GT system.

The key to success is making sure you pick an HVAC contractor AND builder that know what they are doing. If the builder has never touched GT then find one who has.

Find a local HVAC team who has done many installs - been in GT for a long time (hopefully your builder already has someone they have used.) Talk to their customers - make sure they provide good installs & good service. These GT systems are wonderful but you need experienced people to design them properly and fix them when they break.

Thank you so much Minnt and Sniffdog. It's encouraging to hear positive reports on geothermal. We're in the very beginning stages - just retaining an architect - and I clearly have much to learn. Your posts are very helpful.

Wow Minnt, I didn't realize the size of your trenches until I pulled up the pictures with the men standing in them!

And Sniffdog, nice to hear about your success with cellulose and 2 x 6 framing. That's also something we're considering. Thanks again.

We were fortunate in that we didn't encounter any boulders or big problems with our dig. We had to remove a few trees, but because we had a large pasture area, we were able to do most of the digging in the area without trees. It was a two day process. We had a great excavator and a great HVAC team. It was their first GT system install, but they had great support from their supplier, who happens to have an office in a nearby town. I know I took a risk in going with them, I know, but it all went well.