How many of you have used them on projects? Did you use horizontal or vertical pipe layouts? What are your thoughts on the system?
Wood Guy
Jun 27, 23 3:30 pm
I have not used them but have looked into them many times at client request. For residential projects in cold climates, at least here in the northeast US where soil depth to bedrock is shallow and sites are too small for horizontal loops, they almost never make financial sense compared to an air source heat pump system.
The last time I looked into it was for an excavator's house on a large lot with deep soil; they could do horizontal loops for material cost only. Yet air-source heat pumps were a better value.
Ground-source systems also risk contaminating the groundwater due to the glycol mix often used; there are pressurized systems that use potable water but they are rare and even more expensive than typical systems.
I had one client on a lake who wanted to use the lake as the heat sink, which might have penciled out but would have required excessive permitting and more importantly was at high risk (in my opinion) of contaminating the lake water.
From what I have heard, ground-source systems could make sense for larger projects. I'm not exactly sure why, and I haven't researched it since I only design relatively modest homes.
A pet peeve: they are ground-source heat pumps. Geothermal is when the earth provides the heat, common in Iceland. A ground source heat pump uses the earth as a heat sink. "Geothermal" sounds more interesting though.
Chad Miller
Jun 27, 23 3:36 pm
In this particular situation the system would be used for heating and cooling. I've only ever done horizontal loop systems.
Non Sequitur
Jun 27, 23 3:59 pm
WG, using lakes/rivers is prohibited in my area because of the very serious risk of causing permafrost.
Chad Miller
Jun 27, 23 4:47 pm
I thought you used maple syrup for the fluid though?
Richard Balkins
Jun 27, 23 4:53 pm
If you have fairly shallow earth to solid bedrock, I'd probably say you are likely have to use horizontal but it will usually require more ground area. There's good books on this. One such book I have which is more technical and engineering oriented is: Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide (Geothermal Installer Manuals). There's others out there as well.
Chad Miller
Jun 27, 23 5:30 pm
Thanks Rick. I'm also looking for peoples experiences with Ground Source Heat Pumps / Geothermal on past / current projects.
Non Sequitur
Jun 27, 23 5:38 pm
Chad, unfortunately, unlike glycol, maple syrup is prone to freezing. Sorry.
Chad Miller
Jun 27, 23 5:41 pm
I thought GOOD maple syrup was resistant to freezing. I guess you don't have good maple syrup.
::ducks to avoid hockey puck::
Just kidding!
Richard Balkins
Jun 27, 23 7:07 pm
I do work with it on occassion within my local area. However, I apologize for not having a more detailed response for your particular project in your local environment and conditions. Add to it being a little busy..
Richard Balkins
Jun 27, 23 7:14 pm
Geothermal Heating & Cooling for heating and cooling buildings is ground source heat pump (heat exchanger) system. The type of heating wood guy refers to are generally reserved for "Geothermal power" applications. Those would be far more cost-prohibitive and excessive for heating homes and most buildings on an individual building/property level. Technically, the earth doesn't generate its heat. It's just absorbed solar energy that gets captured deeper in the earth.
More for basic primer for others on the forum who may just be learning about "geothermal".
midlander
Jun 28, 23 3:16 am
nitpicking, but this is incorrect: the earth's internal heat (which true geothermal taps) is thought to be leftover from the gravitational compression that formed earth, plus radioactive decay. the earth's interior will generate heat long after the sun burns out. google it.
Wood Guy
Jun 28, 23 11:12 am
Non, it might be prohibited here as well to use lakes for heat sink/source, I didn't get far into it.
Richard Balkins
Jun 28, 23 3:17 pm
Even that, midlander is driven by the energy of the sun. There is a lot of solar energy that penetrates deep into the core of the earth. The sun's x-rays and gamma does penetrate. It's also part of the reason the mantle layer and core is still, well... hot. Otherwise, it would have cooled down and solidified a bit and the core being colder... closer to that of Mars. There's latent absorbed solar energy. Billions of years worth that penetrated. In the early days of Earth, Earth was a bit closer to the sun and that heat most certainly is still contained like a hot coal. Yes, I agree that gravitational compression and some radioactive decay slowed down cooling but Earth's still continue to absorb solar energy from the sun. The deep penetrating x-ray and gamma is transformed into heat. Solar gravitational energy, (another solar energy) is also inducing energy into the Earth. The sun, essentially, animates the solar system. The sun even induced energy into the very material Earth is made of, even that which is radioactively emitting (releasing). A large part came from the sun and some from other stars throughout the galaxy and all. There is some residual energy from the Big Bang. When I am talking about solar energy, I'm not just talking IR emission from the sun. Ultimately, all energy of the universe can be said to trace back to the singularity (current main theory among other theories) at the beginning of this universe. All the planets of the solar system are effected by the gravitational forces (energy) of the sun. I'm pretty sure that energy is also part of what's keeping the core warm and not cooled off. Will it continue for awhile, yes. After you heat coal with fire, for example, does the coal suddenly become cold after it has been made glowing hot? Likewise, it would cool off slowly but once the sun and even its gravitational energy ends, Earth will cool off.
Chad Miller
Jun 28, 23 3:23 pm
We're not going to argue about the sun / earth aspect of this topic. This is the ONLY warning I will give on this.
Richard Balkins
Jun 28, 23 4:32 pm
Fair enough. No arguments needed. The aspect that matters for ground-source heat pumps is in fact the solar energy contained in the underlying soil on the property and the heat exchange process. However, I think you are clear about the fundamental principles, here.
Richard Balkins
Jun 28, 23 4:38 pm
Wood Guy,
Natural lakes would likely be prohibited but might not be for some artificial bodies of water.... like on a large property, one might make a sizable pond that can be used that way. As long as you are properly mitigating environmental impact.
Non Sequitur
Jun 28, 23 5:08 pm
Ricky, we had a recent project disappear but we had a team looking into tapping the heat of the sewer pipes as part of the building systems. I guess you do anything when there is nearly 2 billion dollars at play. COVID killed the project tho.
Richard Balkins
Jun 28, 23 7:49 pm
Yep. $2 Billion to play. COVID f---ed a number of projects.
Non Sequitur
Jun 28, 23 8:04 pm
about 1.8 billion loonies was about what our proposal came in. Not sure what that comes out to in freedom dollars, but the point was that there was a real goal of "wrapping" large municipal sewers and heating/cooling the project.
Richard Balkins
Jun 28, 23 8:37 pm
I can see the value of the project proposal. Perhaps I should have put the C in front as in C$ or CA$ to reference Canadian dollars. In U.S., that's maybe $1.25 to $1.5 Billion USD. Don't recall the exact exchange rate from a few years back but they seemed to be around $0.70 to $0.80 USD (most of the time about $0.75) for every $1.00 CA$.
Nam Henderson
Aug 27, 23 11:56 pm
The "new" National Western Center and Colorado State University Spur utilizes sewage-to-energy exchange.
Chad Miller
Jun 27, 23 5:43 pm
On a related topic:
What are people finding the testing for a ground source heat pump are costing in your area? Our area (western CO) is $50k for drilling once vertical test.
Wood Guy
Jun 28, 23 11:16 am
I don't have specific numbers but I'm surprised it's that expensive. Drilling wells for potable water here starts at $5500 the last I checked; that's for 20' of casing, a 400' well and a submersible pump. It's been a few years so probably more like $7K now. Additional casing, fracking etc. all cost more. I'm not sure how they do the grouting, maybe like a chimney liner, using a long balloon as an inner form?
Chad Miller
Jun 28, 23 11:33 am
My understanding is they basically install a vertical loop system and then test it. It's a 3/4" plastic pipe loop that will go 250 feet down and then up. There is a 8" - 12" dia steel pipe around the plastic pipe that is then filled solid with grout. If the test is good then that is the loop system you use for the ground source heat pump.
natematt
Jun 27, 23 7:13 pm
I've never used them, but I had two projects I knew about that did them, both vertical, both had issues with them not performing as desired....
justavisual
Jun 28, 23 6:47 am
We've used them in Europe. Vertical systems to 116m depth - 5 or 6 of them looped. There's no rock here so that makes it easier. They're closed systems so there is no groundwater contamination.
Chad Miller
Jun 28, 23 10:55 am
It's supposed to be a closed loop. It's still just a 3/4" dia pipe that's 200 feet long encased in grout. Leaks are possible.
Wood Guy
Jun 28, 23 11:19 am
There are also of "pump-and-dump" systems, which cost less than closed-loop systems.
Chad Miller
Jun 28, 23 11:32 am
I've never heard of those systems. Thanks WG!
justavisual
Jun 28, 23 8:28 am
The horizontal ones can be bad news for gardens - heard some stories of plants dying bc of the ground getting colder than usual. Also they limit where you can put trees etc.
JLC-1
Jun 29, 23 12:29 pm
We used it in one house about 6 years ago, as a mitigation resource for snowmelt (in lieu of fees, the system is supposed to pay for itself in a number of years). The one problem we had was the drill tapping an aquifer and a water leak that lasted about a year, it was complicated because the state got involved since it's underground water, not easy to plug. In the end I think it's working fine, this is at 8500 ft with 6 months of snow on the ground. PS the owner of the geothermal company was a pedant, a know-it all type of guy , and he had to eat a lot of his words with the leak and the plugging.
JLC-1
Jun 29, 23 12:37 pm
just looked at the contract, it was 700k for 48 loops 300' deep plus all the piping inside and pumps. Only one test bore though, "Driller will bore one test hole to verify site conditions match Colo DWR Historical Drilling Logs".
JLC-1
Jun 29, 23 12:37 pm
but there was 350k in tax credits.
Chad Miller
Aug 28, 23 9:07 am
So an update on this process.
The project is located in a mountain town in western Colorado, climate zone 7.
To provide geothermal ground source heat pump that provides heating and cooling to two buildings totaling around 28,000 sf will cost $1.7 million. This will require 40 wells.
To provide heating and cooling for the buildings and add 3,200 sf snow melt in the exterior slabs is $4.7 million. This is because it's an unbalanced system with only heat being provided to the concrete slabs. This would require about 160 wells.
Non Sequitur
Aug 28, 23 9:49 am
I don't know if that's a lot or not....
JLC-1
Aug 28, 23 11:29 am
$170 sq/ft with a system that will pay for itself in 10 years, not bad.
Chad Miller
Aug 28, 23 3:22 pm
Non - it's not a bad price for the buildings. It's incredibly expensive for the snow melt in the slabs.
JCL-1 - it's just shy of double the price of a VRF system with backup heat.
JLC-1
Aug 29, 23 5:57 pm
is that with the applicable tax credits?
Chad Miller
Aug 29, 23 7:19 pm
No. It's the cost of the system without any grants or tax credits. The tax credits don't reduce the owners up front cost though - especially since this is fire department and they're already tax exempt.
Wood Guy
Sep 1, 23 8:18 am
For anyone with GBA membership, or willing to do a free trial, this is an interesting article about ground source heat pumps: https://www.greenbuildingadvis....
The title says it all.
How many of you have used them on projects? Did you use horizontal or vertical pipe layouts? What are your thoughts on the system?
I have not used them but have looked into them many times at client request. For residential projects in cold climates, at least here in the northeast US where soil depth to bedrock is shallow and sites are too small for horizontal loops, they almost never make financial sense compared to an air source heat pump system.
The last time I looked into it was for an excavator's house on a large lot with deep soil; they could do horizontal loops for material cost only. Yet air-source heat pumps were a better value.
Ground-source systems also risk contaminating the groundwater due to the glycol mix often used; there are pressurized systems that use potable water but they are rare and even more expensive than typical systems.
I had one client on a lake who wanted to use the lake as the heat sink, which might have penciled out but would have required excessive permitting and more importantly was at high risk (in my opinion) of contaminating the lake water.
From what I have heard, ground-source systems could make sense for larger projects. I'm not exactly sure why, and I haven't researched it since I only design relatively modest homes.
A pet peeve: they are ground-source heat pumps. Geothermal is when the earth provides the heat, common in Iceland. A ground source heat pump uses the earth as a heat sink. "Geothermal" sounds more interesting though.
In this particular situation the system would be used for heating and cooling. I've only ever done horizontal loop systems.
WG, using lakes/rivers is prohibited in my area because of the very serious risk of causing permafrost.
I thought you used maple syrup for the fluid though?
If you have fairly shallow earth to solid bedrock, I'd probably say you are likely have to use horizontal but it will usually require more ground area. There's good books on this. One such book I have which is more technical and engineering oriented is: Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide (Geothermal Installer Manuals). There's others out there as well.
Thanks Rick. I'm also looking for peoples experiences with Ground Source Heat Pumps / Geothermal on past / current projects.
Chad, unfortunately, unlike glycol, maple syrup is prone to freezing. Sorry.
I thought GOOD maple syrup was resistant to freezing. I guess you don't have good maple syrup.
::ducks to avoid hockey puck::
Just kidding!
I do work with it on occassion within my local area. However, I apologize for not having a more detailed response for your particular project in your local environment and conditions. Add to it being a little busy..
Geothermal Heating & Cooling for heating and cooling buildings is ground source heat pump (heat exchanger) system. The type of heating wood guy refers to are generally reserved for "Geothermal power" applications. Those would be far more cost-prohibitive and excessive for heating homes and most buildings on an individual building/property level. Technically, the earth doesn't generate its heat. It's just absorbed solar energy that gets captured deeper in the earth.
More for basic primer for others on the forum who may just be learning about "geothermal".
nitpicking, but this is incorrect: the earth's internal heat (which true geothermal taps) is thought to be leftover from the gravitational compression that formed earth, plus radioactive decay. the earth's interior will generate heat long after the sun burns out. google it.
Non, it might be prohibited here as well to use lakes for heat sink/source, I didn't get far into it.
Even that, midlander is driven by the energy of the sun. There is a lot of solar energy that penetrates deep into the core of the earth. The sun's x-rays and gamma does penetrate. It's also part of the reason the mantle layer and core is still, well... hot. Otherwise, it would have cooled down and solidified a bit and the core being colder... closer to that of Mars. There's latent absorbed solar energy. Billions of years worth that penetrated. In the early days of Earth, Earth was a bit closer to the sun and that heat most certainly is still contained like a hot coal. Yes, I agree that gravitational compression and some radioactive decay slowed down cooling but Earth's still continue to absorb solar energy from the sun. The deep penetrating x-ray and gamma is transformed into heat. Solar gravitational energy, (another solar energy) is also inducing energy into the Earth. The sun, essentially, animates the solar system. The sun even induced energy into the very material Earth is made of, even that which is radioactively emitting (releasing). A large part came from the sun and some from other stars throughout the galaxy and all. There is some residual energy from the Big Bang. When I am talking about solar energy, I'm not just talking IR emission from the sun. Ultimately, all energy of the universe can be said to trace back to the singularity (current main theory among other theories) at the beginning of this universe. All the planets of the solar system are effected by the gravitational forces (energy) of the sun. I'm pretty sure that energy is also part of what's keeping the core warm and not cooled off. Will it continue for awhile, yes. After you heat coal with fire, for example, does the coal suddenly become cold after it has been made glowing hot? Likewise, it would cool off slowly but once the sun and even its gravitational energy ends, Earth will cool off.
We're not going to argue about the sun / earth aspect of this topic. This is the ONLY warning I will give on this.
Fair enough. No arguments needed. The aspect that matters for ground-source heat pumps is in fact the solar energy contained in the underlying soil on the property and the heat exchange process. However, I think you are clear about the fundamental principles, here.
Wood Guy,
Natural lakes would likely be prohibited but might not be for some artificial bodies of water.... like on a large property, one might make a sizable pond that can be used that way. As long as you are properly mitigating environmental impact.
Ricky, we had a recent project disappear but we had a team looking into tapping the heat of the sewer pipes as part of the building systems. I guess you do anything when there is nearly 2 billion dollars at play. COVID killed the project tho.
Yep. $2 Billion to play. COVID f---ed a number of projects.
about 1.8 billion loonies was about what our proposal came in. Not sure what that comes out to in freedom dollars, but the point was that there was a real goal of "wrapping" large municipal sewers and heating/cooling the project.
I can see the value of the project proposal. Perhaps I should have put the C in front as in C$ or CA$ to reference Canadian dollars. In U.S., that's maybe $1.25 to $1.5 Billion USD. Don't recall the exact exchange rate from a few years back but they seemed to be around $0.70 to $0.80 USD (most of the time about $0.75) for every $1.00 CA$.
The "new" National Western Center and Colorado State University Spur utilizes sewage-to-energy exchange.
On a related topic:
What are people finding the testing for a ground source heat pump are costing in your area? Our area (western CO) is $50k for drilling once vertical test.
I don't have specific numbers but I'm surprised it's that expensive. Drilling wells for potable water here starts at $5500 the last I checked; that's for 20' of casing, a 400' well and a submersible pump. It's been a few years so probably more like $7K now. Additional casing, fracking etc. all cost more. I'm not sure how they do the grouting, maybe like a chimney liner, using a long balloon as an inner form?
My understanding is they basically install a vertical loop system and then test it. It's a 3/4" plastic pipe loop that will go 250 feet down and then up. There is a 8" - 12" dia steel pipe around the plastic pipe that is then filled solid with grout. If the test is good then that is the loop system you use for the ground source heat pump.
I've never used them, but I had two projects I knew about that did them, both vertical, both had issues with them not performing as desired....
We've used them in Europe. Vertical systems to 116m depth - 5 or 6 of them looped. There's no rock here so that makes it easier. They're closed systems so there is no groundwater contamination.
It's supposed to be a closed loop. It's still just a 3/4" dia pipe that's 200 feet long encased in grout. Leaks are possible.
There are also of "pump-and-dump" systems, which cost less than closed-loop systems.
I've never heard of those systems. Thanks WG!
The horizontal ones can be bad news for gardens - heard some stories of plants dying bc of the ground getting colder than usual. Also they limit where you can put trees etc.
We used it in one house about 6 years ago, as a mitigation resource for snowmelt (in lieu of fees, the system is supposed to pay for itself in a number of years). The one problem we had was the drill tapping an aquifer and a water leak that lasted about a year, it was complicated because the state got involved since it's underground water, not easy to plug. In the end I think it's working fine, this is at 8500 ft with 6 months of snow on the ground. PS the owner of the geothermal company was a pedant, a know-it all type of guy , and he had to eat a lot of his words with the leak and the plugging.
just looked at the contract, it was 700k for 48 loops 300' deep plus all the piping inside and pumps. Only one test bore though, "Driller will bore one test hole to verify site conditions match Colo DWR Historical Drilling Logs".
but there was 350k in tax credits.
So an update on this process.
The project is located in a mountain town in western Colorado, climate zone 7.
To provide geothermal ground source heat pump that provides heating and cooling to two buildings totaling around 28,000 sf will cost $1.7 million. This will require 40 wells.
To provide heating and cooling for the buildings and add 3,200 sf snow melt in the exterior slabs is $4.7 million. This is because it's an unbalanced system with only heat being provided to the concrete slabs. This would require about 160 wells.
I don't know if that's a lot or not....
$170 sq/ft with a system that will pay for itself in 10 years, not bad.
Non - it's not a bad price for the buildings. It's incredibly expensive for the snow melt in the slabs.
JCL-1 - it's just shy of double the price of a VRF system with backup heat.
is that with the applicable tax credits?
No. It's the cost of the system without any grants or tax credits. The tax credits don't reduce the owners up front cost though - especially since this is fire department and they're already tax exempt.
For anyone with GBA membership, or willing to do a free trial, this is an interesting article about ground source heat pumps: https://www.greenbuildingadvis....