Gregw
New Member
Posts:33
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| 01 Sep 2008 10:55 AM |
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Just floating an idea.
I’m building a new ICF home in Kentucky and considering my options for heating / cooling. My top 3 choices are a water loop (Water Furnace), DX Geothermal (Earth Link) and air to air heat pump (Daikin VRV). The installation will need to be a horizontal system because of my property’s soil type (loose and sandy). Vertical loops will require sleeving full length and that cost is too high. I can get quotes for Water Furnace and Earth link but I have an idea for geothermal air to air and want to get some feedback.
Daikin makes a heat pump where the exchanger is indoors and the air is ducted in and out. Why not bury the intake air supply in an appropriately sized drainage pipe? The site is 2 acres, slightly falling away site, I could bury 300 feet of corrugated drain pipe to temper the air going to the heat pump and increase efficiency on the extreme temperature days. The geothermal aspect of this would be completely passive, no moving parts or pumps. Does this make any sense??
(I could not find anything in a search of this forum)
Thanks, Greg |
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Palace Geothermal
Veteran Member
Posts:1609
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| 01 Sep 2008 11:12 AM |
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You will plowing new ground ( sorry for the pun ).
My guess is you would need more like 3000 feet of pipe buried.
Let us know how it goes. |
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Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
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joe.ami
Veteran Member
Posts:4377
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| 01 Sep 2008 06:08 PM |
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What comes to mind is that heat transfer through the ground is slow and airflow through a condenser is not. But hundreds or thousands of feet of pipe would be tempered during the off-cycle..... I suspect your gain would not justify expense.
Good luck,
Joe |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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Brock
Advanced Member
Posts:599
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| 01 Sep 2008 08:47 PM |
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I actually did this sort of by accident. I had a 4-inch line running about 700 feet from our house to a below grade for a drain for back washing our pool sand filter. The first winter I noticed a good amount of air coming in the house through the house end. I put a thermometer in it and sure enough it was about 50F, with an outside temp of about 20F. So I connected it up to a 6-inch Fantech duct fan and let it run. It dropped to about 45 with the increased airflow, but far better then the old furnace intake at 20F. After about 2 days one of our radon detectors started beeping and it was up about 20ppm. Apparently all the joints weren’t sealed well enough and it was leaking in, or the negative pressure was sucking it out of the ground so I shut it all off. With just leaving the pipe open the radon dropped back to 2ppm so I left it that way. The air was also much cooler in summer, about 55F
Anyway it got me to thinking that if you did seal the pipe well enough or maybe just use 1 inch tubing which wouldn't let radon in it might work. But in your case trying to cool the volume of air for a condenser wouldn't cool down much if at all in those large quantities. |
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| Green Bay, WI. - 4 ton horizontal goethermal, 16k gallon indoor pool, 3kw solar PV setup, 2 ton air to air HP, 3400 sq ft |
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joe.ami
Veteran Member
Posts:4377
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| 01 Sep 2008 09:42 PM |
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For winter applications, how about ducting air from the attic?
J |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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Gregw
New Member
Posts:33
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| 02 Sep 2008 05:22 PM |
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Posted By joe.ami on 09/01/2008 6:08 PM
What comes to mind is that heat transfer through the ground is slow and airflow through a condenser is not. But hundreds or thousands of feet of pipe would be tempered during the off-cycle..... I suspect your gain would not justify expense.
Good luck,
Joe The airflow through the pipe will be dictated by the pipe diameter, an over-sized pipe or multiple pipes will create a slow airflow. Also, corrugated drainage pipe has tremendous surface area for heat transfer. Also the VRV (variable refrigerant volume) system requires less airflow, that's why it can be inside the structure. The question would be; could a pipe at 55 degrees ground temperature temper the intake air from, say 20 degrees up to 32 degrees, a delta T of 12 degrees? 30 Degrees is generally the point where air to air heat pumps become too inefficient. |
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Alton
Veteran Member
Posts:2164
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| 02 Sep 2008 07:38 PM |
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I would be concerned that a corrugated pipe would trap moisture from condensation in the grooves. If I planned to breathe the air from this intake pipe, I would prefer a smooth pipe sloped to grade. This I have done for summer cooling. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Gregw
New Member
Posts:33
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| 02 Sep 2008 08:02 PM |
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Would not be breathing the air, it is ducted across the heat pump's heat exchanger and then exhausted.
How did your system work for cooling? Did you have humidity issues. I looked into this type of direct cooling from earth tubes, but they said that ground temperatures could not effectively dehumidify the air in my area of the country. |
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Alton
Veteran Member
Posts:2164
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| 02 Sep 2008 11:19 PM |
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An exhaust fan was used to remove air from the house. Cool air from the earth tubes replaced the exhausted air. This system worked reasonably well in spring and fall. Air conditioning was required in summer to remove the latent heat and moisture from the air. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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183eej
Basic Member
Posts:127
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| 08 Sep 2008 04:27 PM |
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Have you explored sonic drilling for vertical wells? From what little I know about it, sonic drilling appears to be a good candidate to resolve the geologic conditions you have for vertical wells. |
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| Dale Walker<br>EarthTap<br>www.earthtapenergy.com<br>Where the sun never sets on energy savings<br> |
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Gregw
New Member
Posts:33
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| 09 Sep 2008 11:16 AM |
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Posted By 183eej on 09/08/2008 4:27 PM
Have you explored sonic drilling for vertical wells? From what little I know about it, sonic drilling appears to be a good candidate to resolve the geologic conditions you have for vertical wells. Thanks Dale, I just recently read a little about sonic drilling and it sounds like it could work for this type of soil application. Do you know what the cost comparison is with conventional drilling? I have since found out that a horizontal layout for the DX system costs far less than drilled wells, if you have the land area to put it. I have the area so will go that route. Something I will be doing that should enhance the effectiveness of the system on hot / dry days is placing my garden on top of the geo/field and putting in an automatic watering system. On the hottest, dryest days I will be watering the most which should help with the drying out issues that can occur. It also gives me a chance to enhance the soil on the backfill. |
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183eej
Basic Member
Posts:127
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| 09 Sep 2008 12:50 PM |
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Greg,
I don't know enough about it yet to say how it matches up price wise. The cost of the equipment is not terribly different than traditional drilling equipment. Also, from what I have read and seen on video, it is extremely fast so, I would expect the combination of equipment price and speed would tend to keep the cost competitive.
I installed Earthlinked in my home last year in North Texas and the performance is amazing. So, I believe you are making a good choice.
What part of Kentucky? I lived in far western KY back in the 70s before I joined the Navy. Beautiful place. |
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| Dale Walker<br>EarthTap<br>www.earthtapenergy.com<br>Where the sun never sets on energy savings<br> |
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Alton
Veteran Member
Posts:2164
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| 09 Sep 2008 01:52 PM |
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Greg & Dale,
I am from KY also. I grew up between Bowling Green and Owensboro. Greg, if you are close to this area, maybe I can visit your project on one of my visits to KY. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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tuffluckdriller
Advanced Member
Posts:630
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| 09 Sep 2008 11:30 PM |
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Sonic drilling uses a VERY expensive drill head. The head can be retro-fitted to many different drills, as long as they have the horsepower to drive the sonic (at least 250 hp). It is faster drilling, but the tooling is more expensive, and there is higher risk of breaking tooling off in the hole. This, in my company, keeps our price a little higher than what other conventional rigs charge. However, we can be profitable in many formations that other drill rigs hate (loose, cobble, sand, gravel, collapsing, overburden, glacial fill, etc.). |
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| Clark Timothy ([email protected])<br>Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!<br>www.pinksgeothermal.com |
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fmgriffith
New Member
Posts:5
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| 15 Sep 2008 10:48 PM |
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If you are considering an "air to air" heat exchanger, you might want to check out the Acadia heat pump, built in Bangor, Maine. They claim that it can extract energy at 30 degrees below zero fahrenheit! Their website is: http://www.gotohallowell.com/
We are considering this as an alternative to geothermal since it seems to be so hard to find anyone in northern Maine to install geothermal at a reasonable price...
Good luck!
Fred
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tuffluckdriller
Advanced Member
Posts:630
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| 16 Sep 2008 11:50 AM |
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If it extracts energy at -30 deg. F., then what is the cost on the equipment. Not the price of it, but how much longer is that equipment running? And what's the cost to the efficiency? What COP is it when it's -10? How long does the defrost cycle need to run? How efficient (or really how inefficient) is that defrost cycle? What's the life expectancy of that equipment when running under such long hours?
Many brands have claimed that they can extract energy down to -15 or lower, but they don't disclose easily what the efficiencies are to that. They don't tell you that the defrost cycle will be running every 20 minutes, and that there's no economic benefit of running it down to those temperatures. Air source heat pumps do have their place, but it's definitely not in the colder areas of the world. |
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| Clark Timothy ([email protected])<br>Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!<br>www.pinksgeothermal.com |
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