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Duffy
11-15-2010, 06:55 PM
The last lot on our street is being built on. The owner is having a ground source heat pump installed to supply heat to radient tubing in both floors.
The drill rig showed up this morning at 7.00, while the compressor had been delivered Saturday. The rig is an Italian design and cost $2,000,000.00. It is about six feet wide, on tracks and the drill stems, in six-foot lengths are stored inside similar lengths of threaded casing mounted on a runaround carousel that surrounds the whole rig. (By the way, apologies to Camdigger and any other drillers.) The rig is deisel/hydrauliic and the compressor, a BIG Sullaire on three axles, supplies power to the hammer drill.
They started drilling at 10.00AM and at 3.00PM when I went to talk and gawk, they were at 350 feet. This area is layered limestone. They thought that they would be done by 6.00PM at 450 feet. It is now 5.35 and they have just begun to pull the drill stem.
While I was asking questions, they explained that the threaded casing was so that they could retrieve it as they grouted the hole. It apparently gives them a considerable cost advantage over the competition who are mostly water well drillers.
By tomorrow afternoon they will have grouted, (using a bentonite/sand mix I think,) a 900 foot hairpin of 1 1/4" polyetheylene pipe, ready to connect to the heat pump. This is supposed to supply all the energy for a 2200 sq ft house, presumbably VERY tightly constructed.
This company expected to do most of its work during the spring to fall building season, but they are so busy they expect to work all winter.
To quote Forrest Gump, "That is all that I have to say about that."

jugs
11-15-2010, 08:20 PM
We need pictures :D

john
:)

aboard_epsilon
11-15-2010, 08:28 PM
The last lot on our street is being built on. The owner is having a ground source heat pump installed to supply heat to radient tubing in both floors.
The drill rig showed up this morning at 7.00, while the compressor had been delivered Saturday. The rig is an Italian design and cost $2,000,000.00. It is about six feet wide, on tracks and the drill stems, in six-foot lengths are stored inside similar lengths of threaded casing mounted on a runaround carousel that surrounds the whole rig. (By the way, apologies to Camdigger and any other drillers.) The rig is deisel/hydrauliic and the compressor, a BIG Sullaire on three axles, supplies power to the hammer drill.
They started drilling at 10.00AM and at 3.00PM when I went to talk and gawk, they were at 350 feet. This area is layered limestone. They thought that they would be done by 6.00PM at 450 feet. It is now 5.35 and they have just begun to pull the drill stem.
While I was asking questions, they explained that the threaded casing was so that they could retrieve it as they grouted the hole. It apparently gives them a considerable cost advantage over the competition who are mostly water well drillers.
By tomorrow afternoon they will have grouted, (using a bentonite/sand mix I think,) a 900 foot hairpin of 1 1/4" polyetheylene pipe, ready to connect to the heat pump. This is supposed to supply all the energy for a 2200 sq ft house, presumbably VERY tightly constructed.
This company expected to do most of its work during the spring to fall building season, but they are so busy they expect to work all winter.
To quote Forrest Gump, "That is all that I have to say about that."

how much is it costing ..to do that over here is £7000 just for the hole .

all the brest.markj

Gravy
11-15-2010, 09:49 PM
smart-aleck guess: "If you have to ask..."

Duct Taper
11-15-2010, 10:11 PM
In our state in the US the ground water heat pumps must use a closed loop system. You can't just pump water out of the ground into the heat pump and then let it flow out on the surface anymore. The well casing holds the closed loop. Does Canada have the same restrictions?

Boucher
11-15-2010, 11:03 PM
Geothermal implies that they are tapping underground heat. This is possible in some areas but for most of the country the underground temperature is the mean average temperature. The earth coupled ground source heat pump just exchanges heat with the ground. Its improved efficiency is due to the ground temperature. If the heating and cooling loads are fairly balanced during the yearly seasons they become more efficient. I was in the water well construction business for thirty-five years. I installed a few of these systems. I took a hard look at getting into that business but decided against it. It is a coming thing but there are some fundamental differences between the two businesses. I didnít want to combine the two.

I will make a couple of observations about the stated facts: To make a profit with a $2,000,000 drilling rig it is going to have to drill a lot of hole footage. The slow drill time for this instance may be related to new equipment etc. That compressor probably burned 150 gal of fuel in 7 hr. That is going to be close to $1.00 per foot of hole just in fuel cost. If you are interested in installing one of these systems find you a contractor with a proven track record. These systems are more efficient and they work. They are not cheap and repairs to the loop system can be expensive. This is not where you want to finance someone elseís on the job training.

Duffy
11-15-2010, 11:54 PM
I think that the hole costs about $20.00/ft so $9000.00 in this case. I heard a figure of $30,000.00 for a forced air system, complete with ductwork and heat pump for a house in the next block. I have no idea what a radiant floor system for both floors will cost.
My understanding is there are only three "types" of system; open loop with groundwater discharged to a stream, closed loop with groundwater circulated through the heat pump and returned to another nearby well, and a "sealed system" (my term,) where glycol is circulated through a closed pipe that is grouted into a dry well, or snaked in a trench about 5 or 6 feet deep. This choice requires more space and at least 6 feet of dirt. Here we have 18 to 24 inches of soil over limestone.
An open loop system probably is not allowed here in Quebec , (each province has its own laws regarding use of groundwater.) BUT the question is moot, since it would be hard to get rid of near-freezing water at about 20 gallons per minute when it is minus 30 degrees, either farenheit or celcius!
I believe that the best choice would be a closed loop, PROVIDED that you can get enough water at a reasonably shallow depth. System designers dont like them because there are too many variables that affect the total cost. With a sealed system all they need to know is how big the house is and the can quote a firm price for the job. The quote MAY make you faint!
Sorry that there are no pictures, but it was nearly dark when I posted, and i never thought to take any.

winchman
11-16-2010, 02:47 AM
Another plus for these systems is how quiet they are. The heat/AC system I installed in the house I built in SC was quieter inside than any frost-free refrigerator I've ever owned. There was no noise at all outside.

It seems like the grout around the hairpin of tubing would be counter-productive, since it would slow the exchange of heat. I suppose it's required to keep water from flowing between the various layers of earth the well passes through, though.

Boucher
11-16-2010, 10:11 AM
Another plus for these systems is how quiet they are. The heat/AC system I installed in the house I built in SC was quieter inside than any frost-free refrigerator I've ever owned. There was no noise at all outside.

It seems like the grout around the hairpin of tubing would be counter-productive, since it would slow the exchange of heat. I suppose it's required to keep water from flowing between the various layers of earth the well passes through, though.

In addition to being quiet, they maintain a much more uniform temperature at a much reduced cost of operation. The grout used in these systems has additives to increase its thermal conductativity (Probably something like the weighting additives used in mud in the oil patch)

tdmidget
11-16-2010, 10:37 AM
I find it hard to believe that you would be allowed to pump ethylene glycol, a deadly poison , into the aquifer, grouted or not. There should be no need of it as the ground temperature down there is well above freezing.

Duffy
11-16-2010, 10:57 AM
Boucher, I think that your comments are right on the money. As far as geothermal vs ground temperature, it is really semantics: whether it is REALLY hot rock or just warmer than the outdoors, it is still heat. I think the term in this case derives from the company name; Geothermique and the Frenglish colloquial conversion is to geothermal as it is quicker than "ground source."
As far as drilling goes, you have me. I thought 450 feet in a day was pretty quick. There is no doubt that compressor is thirsty. The comment was made to me that it drank twice as much as the drill unit, so fuel costs would total about $1.50/foot. As far as paying for the drill rig, my cynical mind says that it is heavily mortgaged, and when the profits fall off, the company will go bankrupt. It seems to be a popular business practice here in Quebec.
The incentive for these systems is a couple of federal and provincial grants totalling about $7000.00. I suspect that the cost is inflated by the amount of the grants, and THAT is the company's "operating cushion."
A six inch water well cost $19.00/foot cased, (2009,) screen, pump plumbing wiring, etc. all extra. It seems to me that a similar open hole, (except for the first two lenghts of casing,) should be cheaper by the cost of casing. The cost of grouting in the 900 feet of 1 1/4" PE pipe should bring the cost of the well to about $12,000.00. A three ton heat pump SHOULD cost about $3000.00 installed. Here NOBODY builds a house with less than a 200amp service, so there are no hidden extras there. How then does the cost of the system get to be $25,000.00? Factor in the grants!
They are definitely cheaper than fuel, but the payback is about equal to the life of the heat pump, and most people around here only keep a house about 5-6 years. I am different, we have lived in this one for 22 years.

vincemulhollon
11-16-2010, 04:21 PM
I find it hard to believe that you would be allowed to pump ethylene glycol, a deadly poison , into the aquifer, grouted or not. There should be no need of it as the ground temperature down there is well above freezing.

I would imagine they use its slightly more expensive and completely edible cousin Propylene Glycol. It's quite harmless, depending on your junk food consumption and hand lotion use, you probably eat a couple grams per day. It is not the most toxic chemical in your junk food either on an individual basis or bulk. I am told its easier to get killed by drinking large amounts of water, quick absorption screws up your electrolytes, than by drinking PG, because there's literally no way you can adsorb it thru your stomach wall fast enough to get the rather high lethal dose. I would advise not trying that experiment, but thats what I heard.

Its amazing what one extra carbon atom in the chain will do to reduce toxicity. Ethylene glycol is a quick painful trip to the morgue, but PG is pretty much harmless. EG burns pretty well if you get it hot enough (with dangerous fumes) but PG is relatively safe. PG will make a nice nontoxic smoke when overheated rather than burn, most times. Frankly I'm amazed the greenies still allow EG antifreeze in cars instead of requiring PG.

If you run 60% glycol it wont freeze until -60. That is easy to remember. You can't run a water evaporator/exchanger unit below 32 you'll freeze it. You can run a glycol evaporator/exchanger to about -40 or so with plenty of margin of safety, assuming decent circulation pumps. To know if that makes thermodynamic/economic sense you'll need a lot more information about the compressor and refrigerant. The higher the delta T the higher the heat flux so on a pure "watts transferred" basis you may require your heat pump exhaust to be very cold on a cold day.

http://en.wikipedia.org/wiki/Propylene_glycol

mike os
11-16-2010, 05:32 PM
the temperature gradient on this kind of system is really quite small, basically a fridge run both ways ... hot or cold.

typical efficiency is 250-400+% of the input energy dependant on the system.

Borehole is usually filled/grouted with bentonite to aid thermal contact between ground loop pipe and ground..... pipe is usually very tough & leaks are rare if insalled correctly, so water contamination is not often an issue,

If I could afford it I would install one now.:D

Duffy
11-16-2010, 07:18 PM
My bad! It will almost certainly be propylene glycol for the reasons given. Also, I learned today that the static water level is 8 feet. It only took three bags of grout to seal the well, but it means that the thermal efficiency will be as good as it gets. Of 900feet of pipe, everything below the frost line, 884 feet, is surrounded by water.
This is just good luck, the usual system is dry.