Geothermal Heat Transfer Excavation Costs?

[Caterpillar Cowboy]

Anybody who'se done it have a quick roundabout number for the cost of materials and install labor and the cost of the excavation it'sself? I've been wondering as I've heard it's expensive to put in, but I do plan on doing the excavation for it myself...

 

[kd3pc]

$15-20K

vertical or horizontal.?....our wells were fairly expensive, but they were drilled.

local area will impact costs, bare rental of equipment, operator salary, engineering, etc.

Not really enough info to give you an idea, but if you are doing it yourself, why would it matter.

 

[Milton Shaw]

Each ton of cooling will require a well 240 foot deep, then a loop and filled with grout. That's for a vertical system. A horizontal system needs to be buried about 4 feet or more deep and the length is dependent upon the average ground temp in your area. Either way is expensive and in the range of 15-20K as suggested above. These loops are heat welded pipe and should be engineered by HVAC company according to site/zoning/code restrictions. Cheaper to run over the years but expensive to install. If you have a lake/pond it can possible be used for the heat exchanger. Open system is if you use a water well for supply and then recharge the ground water down another well on the property. This well water must be drinkable, good water to prevent problems with scale build up in heat exchanger.

 

[ratdoggy]

I looked into while my house was being built. Luckily for me I have gas available at my house and it costs me $68 per month to heat, cook,dry clothes and run a fireplace. I didn't do it as the cost was way too high and there would not be a ROI at all.

 

[kd3pc]

If you have a lake/pond it can possible be used for the heat exchanger.

The lake or pond has to be of a certain size, depth, ownership and such. Many states (VA, NC and MD, that I know of) will not risk permitting their use, as the EPA has not approved the use of plastics, like the loops are made of, as they may "leach" or cause issues; or the "installation and intrusion upon wetlands". The feds have gotten pretty invasive in things that may or may not affect water, wetlands and such...

Not a chance of using shoreline of navigable waters, either - too many alphabet cabinets all claiming jurisdiction. Again, Virginia "waters" are owned by the state of MD and their is no process to get MD to approve anything that tethers to VA property.

best of luck.

 

[Zick]

Each ton of cooling will require a well 240 foot deep, then a loop and filled with grout. That's for a vertical system. A horizontal system needs to be buried about 4 feet or more deep and the length is dependent upon the average ground temp in your area. Either way is expensive and in the range of 15-20K as suggested above. These loops are heat welded pipe and should be engineered by HVAC company according to site/zoning/code restrictions. Cheaper to run over the years but expensive to install. If you have a lake/pond it can possible be used for the heat exchanger. Open system is if you use a water well for supply and then recharge the ground water down another well on the property. This well water must be drinkable, good water to prevent problems with scale build up in heat exchanger.

Not to disagree but we had a vertical Geo system installed 5 yrs ago and only needed 150' wells per ton and it works great.
It costs us about $10K for the vertical wells so it's definitely not cheap.

 

[volleyball]

Depth for a vertical depends on what you have down there. Also if you go deeper, you have less need for aux. heat. So it does pay over time.
But I am assuming the OP is talking about a loop as he is going to be excavating and not many of us have access to a well machine.
I would think $5k for a loop and $15k for wells.

 

[sms1974]

Depends greatly on your ground conditions, temps, soil type and composition... In northern ohio vertical bores ( wells ) average 135-150 feet per ton, horizontal loops can be 300-600 feet again depending... The pipping, HDPE, is relativity cheap per foot but requires specialized tools to fuse it properly, along with skills...

The cost is in the labor and equipment... The last 4 ton horizontal loop we had done was $6200 installed, the 4 ton geothermal unit and duct system was $16k

So figure $23k
total minus 30% back -$6900.
So $16,100. Total

Typical furnace and AC in a new house runs around 10-12

If your in an area where natural gas is not available geothermal really is the best way to go...

 

[theoldwizard1]

Each ton of cooling will require a well 240 foot deep, then a loop and filled with grout.

... we had a vertical Geo system installed 5 yrs ago and only needed 150' wells per ton and it works great.

WOW ! Big difference !!

If the well is grouted, that would mean any failure would result in abandoning the well and drilling another. Correct ?

I assume the pipes contain water or non-toxic antifreeze. That is brought back to the house and run through a refrigerant-to-water heat exchanger. Correct ?

Hopefully that exchanger is stainless steel.

 

[sms1974]

WOW ! Big difference !!

If the well is grouted, that would mean any failure would result in abandoning the well and drilling another. Correct ?

I assume the pipes contain water or non-toxic antifreeze. That is brought back to the house and run through a refrigerant-to-water heat exchanger. Correct ?

Hopefully that exchanger is stainless steel.

Geography and geology will greatly affect the bore /well depth...

Any problems with a ground loop after installation will mean abandoning the loop and starting over. More work to find and repair the problem then putting in a new one.

Loop fluid is water and antifreeze, methanol is the most common used in my area but there are other products. When we finish a loop it's fluid is basically 50 proof vodka in it. no you don't want to drink it...

Lastly the heat exchanger is called a coax and is either copper or cupronickel.

Scotty

 

[volleyball]

Why would you abandon the well? grout is easier to drill than solid rock. And most of it is plastic pipe. Now if you hit a aquifer.

 

[theoldwizard1]

Lastly the heat exchanger is called a coax and is either copper or cupronickel.

I guess SS would be too expensive.

Which of those 2 is more durable ? Significant cost differences ?

 

[86turbodsl]

Our loop is horizontal, 300 ft long trenches, 2 trenches, 2 loops per trench, set at 6' depth. Cost in 09' was 1600 / ton. Total ground loop cost was 6400. This in southern Michigan.

 

[ChrisCrane]

I did it my myself and i have a little under 2000 dollars in the 4200 ft (7-600ft loops horizontal) of pipe and the 7 circuit manifold and probably several hundred gallons of diesel fuel for the dozer and backhoe

 

[walrus]

I know a local professor who buried a loop or 2 of black plastic for research here in central Maine, he had the ground frozen by december Not sure of all the details but it sure wasn't enough pipe in the ground in Maine.

 

[sms1974]

Why would you abandon the well? grout is easier to drill than solid rock. And most of it is plastic pipe. Now if you hit a aquifer.

It's just common practice to drill new bores rather than try to clean the existing one out. I will tell you in 25 years I've never had loop fail that wasn't due to someone's negligence, ie dug up or I've one that they shot a post hole in to...

As for coax material it's typically copper if you have a closed loop. Meaning the water is contained. Cupronickel is used of your using an open loop, ground source water that is untreated like a true well you pull water from the ground then dump it back in the ground at a different location.

An open loop is more energy efficient as the water will be closer to ground temperatures, 45/55 degrees. Where as a closed loop can have temperatures down in the 20's by the end of winter.