It's too hard to generalize what will have to change to make GSHP less costly, given the widely differing ground conditions in various parts of the country (water quality, soil moisture content and conductivity, slope, lot size, etc. I can soapbox only on my own situation. The new house is well along in construction (central NH). It will be superinsulated, and that reduces the heat load and thus the size of whatever heating system equipment would be needed. Because water quality is generally plentifull and good in the northeast, and because the house is in a rural area needing a drilled well for domestic use anyway, GSHP (standing column well) is a natural choice. As it turns out, the unit will be either a 2 or 3 ton unit, depending on how well the blower door test goes, needing nominally 160-240 feet of water column in the well. As expected in this area, the driller had to go to 330 feet to get adequate water flow, more than needed for the heat pump. The casing installed was 8" rather than 6", and a return line to the well had to be laid in. Otherwise the extra drilling cost due to use of GSHP was zero.

If the house were merely to code in construction, the load would be much higher, the house would be less comfortable in winter, and some incremental drilling cost and HP size and power use would have resulted. The first decision was to make the house highly energy inefficient, which had nothing to do with choice of how to heat it. Having made that decision, the choice of GSHP became very attractive.

Obviously this reasoning for advocating GSHP won't apply to every area of the country and not to existing housing. There won't be any general answer to improving the economics of GSHP. I would expect more a collection of area- and situation-dependent cost reduction strategies.

Improving usefulness will reduce effective cost. I think about my (or Bill's) oversized ground loop, the fridge, clothes dryer, and water heater. They all could be running on the same loop along with the heat pump(s). Time for a bit of coordination among appliance manufacturers!

Regards,

Masoud

There are domestic water heaters that run on geo - WF's EWO20 is an example. Whether one can be justified by ROI is another matter.

Clothes drying has been a hot button item for me for years. My monthly peak power demand (15 minute average) runs around 8-9 kW. Of that, almost 6 kW comes from the clothes dryer. There has to be a better way. Several times per year I run searches for "Heat Pump Clothes Dryer" and similar phrases. All I've ever come up with is a very pricey Euro-only Miele.

This has been a good discussion so far.  Thanks.

I wish I could invent:

1.) A hand-held instrument, that poked into the ground, could accurately determine the soil's heat transfer characteristic, even very deep down.  It seems to me that one of the components of higher cost geo installations is the desire to overshoot the estimated soil heat exchanger capacity since it's just a guess.

2.) A different piping material than HDPE.  HDPE requires expensive heat fusion tools that take some learning investment time to use properly.

3.) A DX geo technology that uses R410A and supports multi/variable speed compressors.

4.) A higher output temperature capability (when in heat mode) to lessen the need for expanded capcity duct systems when doing a retrofit to geo.

5.) Published business proceedures that result in maximized business process efficiencies for geo installations.

Best regards,

Bill

Bill,  your quest is admirable and you are not alone.  I attended the IGSHPA convention in Denver a few weeks ago and the high first cost of geo installs were the subject of several presentations.

Staff at the DOE and NREL as well as IGSHPA  and GEO recognize the barrier of high first cost.

Drilling will always be expensive due to the costs involved.  Getting more drillers to compete will not bring down the cost, just put some out of business who think they can drill for less.

Knowing ground conductivity while important is not the answer either.

I wanted to attach a design showing the difference but the file size was was 133kb and the max allowed is 100kb.  Phil can you help out here?  pdf files

Design 1 used a TC of 1.0 Btu/hr ft °F and called for 1728 feet of drilling
Design 2 used a TC of 1.2 BTU/hr ft °F and called for 1576 feet of drilling

So increasing the TC by 20 % reduced the drilled footage by 9%.

Most drillers with a knowledge of the local geology can SWAG the TC with in 20%.

Reducing the drilling cost by less than 10% will do little to lower the first cost of installing a geosystem.

My intent here is not to discount your efforts,  just to offer my perspective.

Posted By a0128958 on 13 Nov 2010 11:04 AM
This has been a good discussion so far.  Thanks.

I wish I could invent:

1.) A hand-held instrument, that poked into the ground, could accurately determine the soil's heat transfer characteristic, even very deep down.  It seems to me that one of the components of higher cost geo installations is the desire to overshoot the estimated soil heat exchanger capacity since it's just a guess.

2.) A different piping material than HDPE.  HDPE requires expensive heat fusion tools that take some learning investment time to use properly.

3.) A DX geo technology that uses R410A and supports multi/variable speed compressors.

4.) A higher output temperature capability (when in heat mode) to lessen the need for expanded capcity duct systems when doing a retrofit to geo.

5.) Published business proceedures that result in maximized business process efficiencies for geo installations.

Best regards,

Bill

Here's what we use:

1) hand held soil tester- post hole digger

2) pex is available for ground loops but for our "do it yourself" business we ultimately decided to stick with HDPE and stab fittings.

3) stick with WTA. Nordic was developing 2 stage DX last I spoke with CEO. Said electric TXV made it doable. IMHO DX still limited by soil TC and more expensive. 

4) this is contrary to "efficiency". Generally highest efficiency heating equipment gets you there with lowest possible delivery temp.

5) then you have to get a bunch of mavericks to read it.......

Much of your wish list truly is out there already, but has yet to be compelling to the guys doing the work.

The thing that drives up my job costs most is time. Mine, the excavators, the electricians, the duct guys....... and expertise. The expanded capacity duct system for instance should already be there for ASHP systems, but there are many more hacks in the conventional ends of the business. My duct work costs more regardless of the kind of system you purchase, because I don't install "code minimum" duct work.

j

“3.) A DX geo technology that uses R410A and supports multi/variable speed compressors.

4.) A higher output temperature capability (when in heat mode) to lessen the need for expanded capacity duct systems when doing a retrofit to geo.”



Nordic does manufacture 2-speed split DX GSHPs using R410a that can be coupled to something like a Carrier Infinity fan coil unit. Check out their on-line manuals that can be downloaded from their site.

http://nordicghp.com/images/stories/PDFs/DX-series/000768man-01-dxs-series-two-stage-r410a.pdf

BTW: Nordic may have the widest & most varied line of GSHPs of virtually any manufacturer.

Higher output temps may be achieved by using propane in DX GSHPs that would normally use R22 - but the HP may have to be located outdoors for safety reasons. I would not recommend trying this; it's more complicated than it seems.


SR

• The amount of time (cost) and expertise (training cost / investment) required for site specific design considerations (i.e. varying soil conditions even from one neighboring location to the next).  Have got to reduce the need, and cost, for evaluating actual soil situation (type, mix, TC, amount of water flow).
• The actual costs of doing site evaluations.
• Reducing the design risks and uncertainties when cost estimating.  Right now, pricing has to be inflated to cover for large uncertainties and risks.
• The actual time required to install the loop (conventional air source heat pumps, or conventional A/C with a furnace, can be installed in a day or less).

• It's difficult to get enough (refrigerant) oil circulating within the system.
• There's a need for increased effort investment to maintain the refrigeration loop integrity and cleanliness.
• Copper tubing and refrigerant are very expensive, and a lot of both is needed.
• Repair and maintenance costs can be high due to more difficult effort needed to recover the refrigerant and to re-charge.
• When there's a leak, detecting where it's at, and/or repairing it can be more difficult.

• Figuring out how to use air-cooled condensers to reduce loop size while still satisfying peak cooling needs (not as applicable to northern climates, though).
• Making some kind of small, residential-scaled cooling tower product to serve the same purpose as air-cooled condenser noted above.
• Some kind of soil additive, to spread throughout the bore hole field, or within 10, 20, 30, or 40 feet of a horizontal loop's pipe, that would soak into the earth to increase the soil's TC on a grand scale.
• Some kind of plates that can be attached to the loops, that would increase the loop's heat transfer surface area.
• A drilling rig size more on the order of a 'Ditch Witch,' that can still dig up to 300' wells. 
• A drilling rig that doesn't cost a fortune, that has water-jet technology or some other hammer drill capability that speeds up drilling times substantially.

It's good to examine these things although I expect they are continually reviewed by some in the field. Exactly when water is suitable for the less expensive open loop is one area that seems to get somewhat imprecise answers. Pipe made especially for increased thermal conductivity may happen.

Some kind of soil additive, to spread throughout the bore hole field, or within 10, 20, 30, or 40 feet of a horizontal loop's pipe, that would soak into the earth to increase the soil's TC on a grand scale.

Other than water via a soaker hose?

Posted By joe.Ami on 14 Nov 2010 10:41 AM

Here's what we use:

1) hand held soil tester- post hole digger ...


The thing that drives up my job costs most is time. Mine, the excavators, ...  ....... and expertise.

Thanks Joe.  I thought your comment on the post hole digger was pretty funny.

Your comments on time helped me to better appreciate how significant this really is.  For example the conventional guys (conventional A/C with a NG furnace) can get in and out of a job, complete, in one day.  The fact that the energy source is 'plug it in to the grid' makes this doable, versus geothermal where it has to be custom 'plugged into the earth' with an installation specific design and engineering of a ground loop.

Best regards,

Bill

Posted By geodean on 13 Nov 2010 12:31 PM
 
... I attended the IGSHPA convention in Denver a few weeks ago and the high first cost of geo installs were the subject of several presentations.

... Drilling will always be expensive due to the costs involved.

Getting more drillers to compete will not bring down the cost, just put some out of business who think they can drill for less.

Knowing ground conductivity while important is not the answer either.  ...

So increasing the TC by 20 % reduced the drilled footage by 9%.

Most drillers with a knowledge of the local geology can SWAG the TC with in 20%.

Reducing the drilling cost by less than 10% will do little to lower the first cost of installing a geosystem. ...

Dewayne, much appreciate the comments.

If it's available for viewing/downloading, I'd appreciate it if you would point to any presentation material places from the convention, related to the high first cost of geo installs.  I'd like to study what's already been written/published.

I appreciate that high capital costs for drilling rigs prevents loop installation costs from going down simply from increased competition.  It makes sense that more geo professionals simply go out of business due to high entry capital cost of equipment.

Thanks for the illustration that increased soil TC accuracy doesn't substantially translate to lower loop install cost.  Looks like the relationship between change in TC is non-linear to change in cost.  And that at least for a residential install, a reasonable TC estimate is all that's needed (versus increased accuracy).

Many thanks!

Best regards,

Bill

Bill some of the presentations are available here.

Hope fully you can find some info there.

Posted By geodean on 17 Nov 2010 08:15 AM
Bill some of the presentations are available here.

Hope fully you can find some info there.

Dewayne, thanks.  I studied the 2010 presentations closely.

Best regards,

Bill