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Posted: 1/23/2021 1:12:52 AM EDT
So tell me how heating (and cooling) works w/ a geothermal system here in the States if you don't have a volcano handy.
This video is making points and I'm not understanding how it all works in the 1st place:  Debunking 3 Geothermal Myths |
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Posted: 1/23/2021 1:18:20 AM EDT
[#1]
The ground supplies a constant temperature heat sink cool enough to dump energy into when cooling the house and warm enough to pull energy from when warming the house via a heat pump. Same as an open air heat pump but doesn't stop working when it gets below freezing outside.
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Posted: 1/23/2021 1:18:22 AM EDT
[#2]
A couple hundred feet down, and it'll keep your house in the 60s, heat pump takes over as needed
Next door neighbor did it, needed a gas furnace to make up the difference for really low - but if it was over about 20f outside, the water kept the house comfortable. Depends on your locale, call drillers to figure out cost and temp. Higher the temp, longer the payback. |
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Posted: 1/23/2021 1:28:25 AM EDT
[#3]
Quote HistoryQuoted: The ground supplies a constant temperature heat sink cool enough to dump energy into when cooling the house and warm enough to pull energy from when warming the house via a heat pump. Same as an open air heat pump but doesn't stop working when it gets below freezing outside. This |
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Posted: 1/23/2021 1:29:02 AM EDT
[#4]
Ok, not like Iceland where you get free heat out of the ground to heat your house. It's just a heat pump that uses underground water instead of air. Makes some sense.
Probably not going to be cost effective down here where we need 1 compressor per floor to keep the house cool in the summer, gas heat is cheap, and winters aren't very cold. |
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Posted: 1/23/2021 1:32:17 AM EDT
[#5]
As they said. Far enough down and the ground is an ambient 50-60 degrees f.
You run a coolant line down and let the coolant get to 50f then compress the shit out of it to raise the temp. Blow air across it to heat your house. Decompress and repeat. OR, Reverse the flow. Compress the shit out of it to raise the temp. Run it underground to cool to 50f. Decompress to drop the temp. Blow air across it to cool your house. Easy peasy, lemon squeezy. |
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Posted: 1/23/2021 1:34:15 AM EDT
[#6]
Quote HistoryQuoted: Ok, not like Iceland where you get free heat out of the ground to heat your house. It's just a heat pump that uses underground water instead of air. Makes some sense. Probably not going to be cost effective down here where we need 1 compressor per floor to keep the house cool in the summer, gas heat is cheap, and winters aren't very cold. If the ground is 60°F, a simple water pump and fan is all you need to cool the house. Even if not enough, cooling is going to be a lot cheaper dumping heat into 70 or 80°F ground compared to 105°F air. The ROI may be the bitch though. |
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Posted: 1/23/2021 1:37:44 AM EDT
[#7]
Friend in Oregon has geothermal. He says the primary downside is there are not many qualified technicians to maintain and service the system. Only guy in his area is well past retirement age
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Posted: 1/23/2021 1:41:57 AM EDT
[#8]
You're basically using the earth's natural temperature as a heat exchanger.
Other than that, it works kind of like a regular HVAC system....kinda. It uses and environmentally friendly (because you'll have a fuck ton of pipe at least 8 feet underground...lengths from half a mile to more than a mile depending on tonnage your home requires) refridgerant. In the summer months, the refrigerant will take the heat from the home and dump it into the earth, thus cooling the refrigerant, thus cooling your home. In the winter months...kind of basically the same thing...but reverse (better explained above) 8+ feet down...its around a constant 65 degrees. Geothermal costs about the same as a conventional HVAC system, and very very efficient. A lot of SEER for your buck. What makes it twice or more expensive is the operating costs of digging or drilling for your lines. I tried to keep it basic....If your home is decently efficient (tight and well insulated), the whole geothermal system will pay for itself in ~7-15 years (depending) |
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Posted: 1/23/2021 1:45:18 AM EDT
[#9]
Geothermal has a high enough temperature difference to have a thermal cycle that produces net work output.
What's being shown in the OP is probably a ground-sink heat pump system. The ground has a more constant temperature and can be a more efficient heat sink than atmospheric air, which can have significant variance in temperature during the course of the year. The hotter the sink temperature the summer, the less efficient the cycle. The colder the the air sink temperature is in the winter, the less efficient the cycle; and if it's cold enough, the cycle isn't possible at all, not in any pragmatic sense. The ground-sink "geothermal" concept doesn't produce net work output, but it allows for more efficient operation of cycles that use net work input. |
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Posted: 1/23/2021 1:50:19 AM EDT
[#10]
That video sucks. I made it 2 1/2 minutes in. I'm going back to listening to some Grateful Dead.
The biggest myth of US residential geothermal is that we call it geothermal. It's simply a conventional vapor cycle heat pump that uses the ground as a sink instead of the outside air. |
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Posted: 1/23/2021 1:52:53 AM EDT
[#11]
Quote HistoryQuoted: 8+ feet down...its around a constant 65 degrees.  |
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Posted: 1/23/2021 2:09:12 AM EDT
[#12]
Quote HistoryQuoted: A couple hundred feet down, and it'll keep your house in the 60s, heat pump takes over as needed Next door neighbor did it, needed a gas furnace to make up the difference for really low - but if it was over about 20f outside, the water kept the house comfortable. Depends on your locale, call drillers to figure out cost and temp. Higher the temp, longer the payback. There's some crazy stuff out there. Some of it is wtf and some of it is wtf that's pretty cool. |
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Posted: 1/23/2021 2:33:19 AM EDT
[#13]
There's a off grid cabin here with a geothermal for power production. Pretty cool. It is old enough that I am sure solar wasn't cost effective.
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Posted: 1/23/2021 3:00:10 AM EDT
[#14]
There are two types of Geothermal heat exchanger loops: open and closed. Everybody in this thread is talking about the closed loop system where the heat exchanger piping is either laid out flat in a yard (horizontal), buried a few feet underground; or drilled down deep into the ground (vertical). In closed loop systems, antifreeze is circulated thru the heat exchanger loop piping to transfer heat between the ground and geo unit.
My geo system uses the open loop setup. Basically it taps into my house water (well) and uses 8 gal/min of well water while its running. Discharge is in my back yard, and it flows into a pond. My geo unit pulls heat out of the well water in the winter and dumps heat into it in the summer. Well water temp is a consistent 58 deg F year round here. More efficient than a heat pump that exchanges heat with the outside air. Basically the most efficient setup you can get with only having electric as a utility. |
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Posted: 1/23/2021 3:28:47 AM EDT
[#15]
Geothermal is one of the most promising non-nuclear 'carbon free' energy sources.
The new style of Enhanced Geothermal Systems (EGS) use Fracking technology to create artificial hot water resevoirs. This allows a massive expansion of where Geothermal can be used. Previously, it had only been available in the rare areas of the globe where there were natural underground hot springs (like Iceland.) With fracking, anywhere the earths crust is over 200 degrees celsius (most of the US West/ Southwest) can have a an artificial resevoir created.  |
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Posted: 1/23/2021 4:50:05 AM EDT
[#16]
I think the OP is technically correct about the term geothermal when the proper terms are ground loop xxxxx or geoexchange or some other terms.
Geothermal has become the catch all word , like Qtip or Kleenex, for the industry that uses the constant temperature of the earth for utilities. |
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Posted: 1/23/2021 5:32:11 AM EDT
[#17]
Quote HistoryQuoted: There are two types of Geothermal heat exchanger loops: open and closed. Everybody in this thread is talking about the closed loop system where the heat exchanger piping is either laid out flat in a yard (horizontal), buried a few feet underground; or drilled down deep into the ground (vertical). In closed loop systems, antifreeze is circulated thru the heat exchanger loop piping to transfer heat between the ground and geo unit. My geo system uses the open loop setup. Basically it taps into my house water (well) and uses 8 gal/min of well water while its running. Discharge is in my back yard, and it flows into a pond. My geo unit pulls heat out of the well water in the winter and dumps heat into it in the summer. Well water temp is a consistent 58 deg F year round here. More efficient than a heat pump that exchanges heat with the outside air. Basically the most efficient setup you can get with only having electric as a utility. In the video, the installer claims that the open loop systems are less-preferred now, because by using a "clean" water/glycol working fluid in a closed system, you can protect your mechanical systems from debris/fouling. Just thought I would comment here since you're the first person to raise that distinction for residential systems. Can you tell us how long ago yours was installed, and has sediment/debris been an issue for you? Any comments on cost? I would really be interested to hear from someone about the cost and capability trade-offs between vertical wells and horizontal loops. It seems drastically easier to me to just drill, unless you were already doing a crazy amount of site work otherwise. |
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Posted: 1/23/2021 5:42:43 AM EDT
[#18]
my parents have geothermal heat in the thumb of Michigan. It is nothing more then a heat pump that uses the earth as its heat source. its a 2200sqft house with 5 slinky loops about 6-7 ft down. They have a waterfurnace envison series heatpump. It's been in for about 10 years they love it. It was our cottage before they retired and leaving it at 65 for the winter before they lived there it was about $60 a month electric bill getting 1/2 price electric from the electrical coop on their interruptible plan which they never have done in the winter summer yes winter no.
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Posted: 1/23/2021 6:22:03 AM EDT
[#19]
My buddy Steve was in that business for a long time working for a company that made arguably the best grout in existence for deep well type heat exchange in closed loop systems. The demand went way down a couple of years ago and the industry is in crisis.
I hope it make a resurgence as it is very efficient. |
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Posted: 1/23/2021 7:06:49 AM EDT
[#20]
Installed in 2008.
SE PA. 3,000 sq ft two story colonial. 3x 250’ wells. $10k drilling $25k system install. Total energy bill now averages $200 a month and it we get hot summers and cold winters. Used to burn 1,000 gallons of oil a year and average $1,000 a year elec. Pulled the trigger when oil hit $4.29 |
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Posted: 1/23/2021 7:22:29 AM EDT
[#21]
Quoted: So tell me how heating (and cooling) works w/ a geothermal system here in the States if you don't have a volcano handy. This video is making points and I'm not understanding how it all works in the 1st place:  https://www.youtube.com/watch?v=GiLns7OFpiYInstead of using a liquid to air condenser coil outside, it circulates liquid down into the ground to pull heat out of the compressed refrigerant. It’s more efficient using the more temp stable subsurface instead of the ambient air, especially in summer. So you can use a smaller system that uses less power for the same size house |
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Posted: 1/23/2021 7:39:44 AM EDT
[#22]
I love my geothermal in the summer. Very cheap to keep the house cold. Plus, it's tied into the water heater. In the winter, it struggles and gets a little expensive. Might just be my unit. I now supplement by using our fireplace more often.
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Posted: 1/23/2021 7:52:21 AM EDT
[#23]
New air to air inverter systems are going to make it rough on geothermal. Seer in the low 20s and heat down to 5 or lower.
Geothermal has a SEER now days of around 40, so they claim. To save, you have to use it a lot. The extra $$ on a new build are probably better spent on a quality foam insulation and an inverter heat pump. |
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Posted: 1/23/2021 8:13:15 AM EDT
[#24]
Quote HistoryQuoted: Friend in Oregon has geothermal. He says the primary downside is there are not many qualified technicians to maintain and service the system. Only guy in his area is well past retirement age A sign of the times. Techs in the trades don't know what the fuck they are doing. There is no difference between air to air heat exchange or water to air, except for the heat exchanger and some different formulas to use. Could really throw these "techs" a curve ball and have them look at a water cooled chiller. For fucks sake what is this world coming to when an HVAC tech can't maintain a simple water to air system |
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Posted: 1/23/2021 9:37:37 AM EDT
[#25]
Quote HistoryQuoted: I think the OP is technically correct about the term geothermal when the proper terms are ground loop xxxxx or geoexchange or some other terms. Geothermal has become the catch all word , like Qtip or Kleenex, for the industry that uses the constant temperature of the earth for utilities. Ah, thanks. Cheers to all for the explanation. |
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Posted: 1/23/2021 9:43:53 AM EDT
[#26]
When people ask me how mine works i just say its magic
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Posted: 1/23/2021 9:59:16 AM EDT
[#27]
I don't think I'd have room for all the equipment...
 Attached File Attached File Attached File Attached FileThese are interior shots from the Svartsengi power station in Iceland on the Reykjanes Peninsula . One of its "waste" products is the famous Blue Lagoon. |
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Posted: 1/23/2021 10:01:41 AM EDT
[#28]
Drilling and grouting vertical systems is pretty expensive.
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Posted: 1/23/2021 10:01:51 AM EDT
[#29]
Quote HistoryQuoted: I don't think I'd have room for all the equipment... https://www.ar15.com/media/mediaFiles/2262/20150826_164901_jpg-1792693.JPG https://www.ar15.com/media/mediaFiles/2262/20150826_165201_jpg-1792694.JPG https://www.ar15.com/media/mediaFiles/2262/20150826_165233_001_jpg-1792695.JPG https://www.ar15.com/media/mediaFiles/2262/20150826_165335_001_1_jpg-1792696.JPG These are interior shots from the Svartsengi power station in Iceland on the Reykjanes Peninsula . One of its "waste" products is the famous Blue Lagoon. The Blue Lagoon is a brilliant piece of marketing. Who'd have thought you could entice tourists to soak in your power plant waste effluent ponds for $60 and then sell them shitty over priced drinks for $15 each. |
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Posted: 1/23/2021 10:05:01 AM EDT
[#30]
ASHPs (air source heat pumps) have become increasingly efficient and with their lower initial cost may be more cost effective over the expected lifespan of the equipment than geothermal. Especially in Texas.
If you're looking at decreasing your energy cost, you may also want to consider a heat pump water heater. As a positive,(especially in Texas) they'll cool and dehumidify the space they are in. I have natural gas and use a Bosch tankless water heater paired with one of their air handlers to heat the house. I also have a heat pump water heater with a tank to buffer everything and as a backup source of heat. This is a picture I found of a similar setups (without the tank) by Rheem and Bosch:  Attached File Attached File |
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Posted: 1/23/2021 10:05:30 AM EDT
[#31]
Several of the homes I'm looking at are geothermal.
It's a pretty cheap method of heating and cooling. The homes typically have a second method of heating and cooling like propane or a wood burning boiler. |
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Posted: 1/23/2021 10:08:23 AM EDT
[#32]
Saw one get installed on a job we did two years ago, it looked very expensive, so the payoff was probably long term.
They dug down 8 feet in horizontal runs, ran loops (pex I think) with sand around them. It was a shit load of tube for a 4000 sq ft house. Inside was a circulation pump and heat pump. The general idea is that in the summer you move heat from inside the house into the ground outside, and in the winter you move heat from the ground into the house. The heat pump handles the difference. Seemed reasonable I guess with the whole house and basement set up to have in floor heat, but I bet the electric cost is substantial in addition to the installation cost. |
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Posted: 1/23/2021 10:18:05 AM EDT
[#33]
Quote HistoryQuoted: Geothermal is one of the most promising non-nuclear 'carbon free' energy sources. The new style of Enhanced Geothermal Systems (EGS) use Fracking technology to create artificial hot water resevoirs. This allows a massive expansion of where Geothermal can be used. Previously, it had only been available in the rare areas of the globe where there were natural underground hot springs (like Iceland.) With fracking, anywhere the earths crust is over 200 degrees celsius (most of the US West/ Southwest) can have a an artificial resevoir created. https://www.greenfireenergy.com/wp-content/uploads/2020/06/GreenFire-EGS-Graph.png I worked in geothermal power for a few years. The above plant would probably have a hard time ever being built. They did something similar at the geysers in Northern California. So after using more geothermal fluid then the resource could handle they started dumping down waste water from Santa Rosa but it cause a shit load of seismic activity. While a cool idea I have a hard time seeing it work. You would need a shitload of makeup water and makeup water is something that is generally impossible to find where geothermal heat is. Related to the OP a couple of the old ranch houses by one plant I worked at pump 130 degree water out of the ground into the house and ran it through old school steam radiators in the house. It worked insanely well. You could make the house 100 degrees when it was arctic outside. Now that I think about it I’m not even sure if they had to pump it since there was such high pressure there. |
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Posted: 1/23/2021 10:25:03 AM EDT
[#34]
Quote HistoryQuoted: Haven't come across a geo/gas system yet. There's some crazy stuff out there. Some of it is wtf and some of it is wtf that's pretty cool. This was 20 years ago, but it was geo/heat pump/gas. About a 4ksf house built in the 1880s, on the line between USDA zone 5 and zone 6. He said the gas only ran about 1-2 weeks a year, but it was the $1,000 gas bill that made him look into geothermal to begin with. |
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Posted: 1/23/2021 10:26:54 AM EDT
[#35]
Quote HistoryQuoted: As they said. Far enough down and the ground is an ambient 50-60 degrees f. You run a coolant line down and let the coolant get to 50f then compress the shit out of it to raise the temp. Blow air across it to heat your house. Decompress and repeat. OR, Reverse the flow. Compress the shit out of it to raise the temp. Run it underground to cool to 50f. Decompress to drop the temp. Blow air across it to cool your house. Easy peasy, lemon squeezy. I thought they pumped the water up to the heat exchanger, then discharged it down a different well? |
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Posted: 1/23/2021 10:32:36 AM EDT
[#36]
My system had coils 6' down. I'm in La.
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Posted: 1/23/2021 10:42:13 AM EDT
[#37]
Quote HistoryQuoted: I think the OP is technically correct about the term geothermal when the proper terms are ground loop xxxxx or geoexchange or some other terms. Geothermal has become the catch all word , like Qtip or Kleenex, for the industry that uses the constant temperature of the earth for utilities. |
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Posted: 1/23/2021 10:50:21 AM EDT
[#38]
Quote HistoryQuoted: Drilling and grouting vertical systems is pretty expensive. This is what I don't get. Why not just have one well with adequate supply and pump the cold water up to a surface heat exchanger and dump the water out from there? They are using wells as heat exchangers when they could simply use an insulated pipe to bring that cool water up to a heat exchanger and save most of the cost of drilling. |
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Posted: 1/23/2021 11:06:29 AM EDT
[#39]
Liberals will find a way to hate it.
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Posted: 1/23/2021 11:13:12 AM EDT
[#40]
My house is geothermal closed loop, it works great, but when I last replaced it the cost was around 12K, if my loop ever goes bad I'm screwed, and if you figure it will need replaced every 15 years or so, I'm not sure how cheap it really is.
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Posted: 1/23/2021 11:13:17 AM EDT
[#41]
Quote HistoryQuoted: This is what I don't get. Why not just have one well with adequate supply and pump the cold water up to a surface heat exchanger and dump the water out from there? They are using wells as heat exchangers when they could simply use an insulated pipe to bring that cool water up to a heat exchanger and save most of the cost of drilling. Most groundwater districts around here only allow ~15 gal a minute to be pumped from a residential well. Discharging that water once used only for HVAC wouldn’t fly too well. Can’t dump it back down the well. Possible aquifer contamination issues. (Though some people do it) Wells around here are also generally pretty deep. 4-500’ on average. |
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Posted: 1/23/2021 11:18:54 AM EDT
[#42]
I have a 4 ton geo unit with 3200’ of horizontal ground loop. I live where natural gas isn’t available or I would have installed a forced air system. A lot of the new systems don’t require ground water. My loop field is 8’ deep where ground temp is always 55 degrees. My loop is filled with an antifreeze type liquid. The system works basically like a solar system and refrigerator using the heat / cold from the ground. It takes the 55 degree liquid and compressed it to make heat in the winter. In the summer it takes heat from the house and dumps into the ground.
Pros- it’s significantly cheaper per month to heat with in the winter than a propane furnace. AC is almost free in the summer. The only real cost is electricity for the circulating pump and the fan to blow it through the house. We turn ours on as soon as it gets warm and it runs 24/7 until we turn it off in Sept. if we get cold we just open doors and windows. It costs about $40 / month to never turn it off. Cons- It’s expensive as fuck. Our unit with installation was a tad over $35,000. When the temp drops quickly it takes the system a day or so to catch up. We offset with a wood stove. |
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Posted: 1/23/2021 11:22:36 AM EDT
[#43]
My in laws in northern Europe have a downhole heat exchanger, it works very well.
I think it is more commonplace in areas with many contractors specialized in drilling and rock removal (my fil is one so he did his own drilling). |
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Posted: 1/23/2021 11:25:15 AM EDT
[#44]
Quote HistoryQuoted: New air to air inverter systems are going to make it rough on geothermal. Seer in the low 20s and heat down to 5 or lower. Geothermal has a SEER now days of around 40, so they claim. To save, you have to use it a lot. The extra $$ on a new build are probably better spent on a quality foam insulation and an inverter heat pump. yea my inverter mini split is pretty neat. Uses some juice to run but still putting out heat when its 15 degrees outside. |
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Posted: 1/23/2021 11:39:23 AM EDT
[#45]
have 3 heat pump jobs on my desk right now. one is replacing 90 furnaces in a nursing home with heat pumps. Luckily all of the indoor geo loop piping for the new units go roughed in before covid really hit, but now it's going to take 2 years to get the job done with the current safety protocols. This particular job has a simple water to water heat exchanger, and we control the pumps to maintain the building loop supply temperature. I think they punched 25 wells for the geo loop.
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Posted: 1/23/2021 11:42:54 AM EDT
[#46]
Old school geothermal before the term was co-opted by marketers meant hot water out of a drilled hole, or a hot spring.
The subsurface temp in southern Missouri is 56F more or less. Enter any wild cave to find out. The temps across the country are available on maps. I am extremely skeptical of heat pumps that rely on low temperatures around ground source loops. See the explanation above in L_JE's post. Forget about air to air heat pumps in cold climates. |
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Posted: 1/23/2021 11:51:44 AM EDT
[#47]
Quote HistoryQuoted: That video sucks. I made it 2 1/2 minutes in. I'm going back to listening to some Grateful Dead. The biggest myth of US residential geothermal is that we call it geothermal. It's simply a conventional vapor cycle heat pump that uses the ground as a sink instead of the outside air.  Grateful Dead - Not Fade Away (Winterland 12/31/78) |
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Posted: 1/23/2021 11:52:24 AM EDT
[#48]
Quote HistoryQuoted: Old school geothermal before the term was co-opted by marketers meant hot water out of a drilled hole, or a hot spring. The subsurface temp in southern Missouri is 56F more or less. Enter any wild cave to find out. The temps across the country are available on maps. I am extremely skeptical of heat pumps that rely on low temperatures around ground source loops. See the explanation above in L_JE's post. Sounds like it works, just very expensive installation. Would significantly lower the solar/battery requirements for an off grid system in the South. |
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Posted: 1/23/2021 11:55:03 AM EDT
[#49]
In Hot Springs Arkansas it comes to you
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Posted: 1/23/2021 12:03:40 PM EDT
[#50]
Quote HistoryQuoted: A sign of the times. Techs in the trades don't know what the fuck they are doing. There is no difference between air to air heat exchange or water to air, except for the heat exchanger and some different formulas to use. Could really throw these "techs" a curve ball and have them look at a water cooled chiller. For fucks sake what is this world coming to when an HVAC tech can't maintain a simple water to air system Licensing |
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