Our Northern Ontario building lot is basically a granite hill. We were able to excavate with a hydraulic hammer and some blasting but basically the only soil we have is what we scraped off the surface and relocated to the back of our lot.

Our house will have a walk-out basement and is nestled behind the hill that was left after the excavation. As a result, the south and west walls are above grade while the north and east walls are half below grade. Also, it will be ICF to the rafters and we are backfilling between the house walls and the rock.

We are designing the windows for passive solar heating due to our exposure to due south at the back. Also, we have an HVAC specialist developing our heat load calculations.

Is geothermal even a consideration in this situation? If so, what would be the best design and installation approach?

Is there anything we should be asking our HVAC guy that pertains specifically to geothermal?

If you can find a driller willing to drill the rocks, geothermal will work fine

Granite will typically cost you more to have drilled, but geothermal will work wonderfully for it. Not knowing your schedule, I don't know how feasible it is, but I'd suggest drilling inside the structure because of the difficulty of excavation. (I'd do an EarthLinked DX loop system inside the house)

Trenching could be a challenge; I too would consider an interior ground loop within the envelope of the foundation. I would install a Nordic DX heat pump. That would be your most cost effective geo solution and it’s Canadian too!

SR

Well, one of our potential heating contractors told me that geothermal is not a good idea in our case. He spoke to his geothermal specialist and learned that it would cost us upward of $25k just for the wells. Plus, the City might not approve us drilling wells due to the fact that we only have surface rights??

Also, he said that we would have to install a back-up system for heating which would further erode any savings.

So, it looks like we're back to conventional Forced Air + Nat. Gas.

Brian.

Just a few thoughts:

I have never heard of a city not allowing drilling for geothermal loops.

Geothermal comes with it's own back up system

It sounds like the person who told you this doesn't normally do geothermal.

Are you in Ontario Canada or New York?

I finally spoke with a contractor that does geothermal. He advised me that having to drill wells coupled with the system cost will make it uneconomic. He has found that if you can bury the tubes or run a lake loop, it really does make sense.

His recommendation was to go with a natural gas combination heater like Triangle Tube.

Bwheeler,

What is your source for domestic water?  Before giving up totally on the geothermal heating I would suggest at least calling a few drilling companies and see if they would give you a quote.  As tuffluckdriller suggested, DX into the basement floor would be a great source for geothermal. 

Hope the best for your new home project,

Sorry, but if it were me, I'd be charging about $12.00-$15.00 per foot for drilling and grouting of the holes for DX--even in that granite. If your system needed 6 tons, then the drilling would be $7,200-$9,000. That's if I were in your area.

Granite is a hard rock, but an air drill can handle it. In fact, I have a small air drill that would do the job just fine. You are, though, too far for me to travel.

$25K just for the drilling is an absurd price. Don't listen to those who don't do it regularly. Contact a DX installer or sales rep.

If you're in Canada, contact Steve Davies at:

[email protected]
Tel: 519-658-4330
Fax: 519-658-9384

He's the EarthLinked DX sales rep for Ontario. He'll know what kind of prices you'd be looking at.

I've been calling some well drillers and they only want to drill 6" water wells. They have no interest in geothermal.

How do I describe the type of hole needed? I also know of folks that drill for blasting purposes but I don't know if they can also drill for geothermal.

You say you have an HVAC calculating your heat load calculations. What about your cooling needs. If they oversize the heat side, so what. When the house gets to desired temperature, it turns itself off. If they oversize the cooling side, the house gets to desired temp, but maybe the dehumidification has not taken place because the run cycle was too short. Have a geothermal guy determine your heat load and cooling req. PCA )portland cement assoc(wwww.forms.org) has put out a program for ($59.00 USD) to determine load calcs for concrete hoams. Yours is a concrete home, correct??!!??.

I have a WaterFurnace geothermal (3.5-5 ton) for a 6,000 sq. foot house with two zones.

The only geothermal contractor that I could find indicated that drilling wells will drive the economics out of reach. Plus, there aren't any drilling contractors around that are willing to drill for geothermal. They are only interested in drilling water wells, 6" diameter.

I'm giving up on geothermal. But, I may end up with Nudura walls!

Has anybody heard of "direct exchange". Apparently it's more efficient and less expensive than conventional geothermal.

- Eliminates a heat exchanger and a pump
- Reduced maintence
- Simpler and faster to install
- Smaller earth loops
- Less disruption to existing landscaping

Information from the Eco-options Goethermal web site.

In referring to DX heat pumps from EarthLinked or Nordic, that's exactly what we were talking about. DX is Direct Exchange.

Those points are correct. DX or Direct Exchange systems do have the benefit of:

- Eliminates a heat exchanger and a pump
- Reduced maintence
- Simpler and faster to install
- Smaller earth loops
- Less disruption to existing landscaping