Geothermal heating for House

[theoldwizard1]

We're not yet at the point where we can abandon coal plants. There are too many of them. There is also a tremendous amount of coal still left in the ground (a 100 year supply by some estimates). The holy grail is for scientists to find a way to burn coal as cleanly as natural gas. They are working on it.

NG is killing coal fired plants off one at a time. Much cheaper and cleaner. If you have NG anywhere close to a coal fired plant, its days are numbers.

There are never any absolutes, so yes we will have coal fired plants for a long time.

 

[Dick in Wisconsin]

I am not a pro, but I have never heard of a electric resistance backup for a ground sourced heat pump. If such a thing was ever needed, the system was designed or installed wrong !

We have a WaterFurnace(r) in a house 25 miles NW of Green Bay (WI). The WaterFurnace came standard (I think) with electric resistance backup. Electric resistance backup is inexpensive to install in the unit and is ready anytime you need it. While there is very little you can do if the POCO fails to provide you power, there are a number of things that can go wrong with a GWHP system that makes having the backup a good idea.

We put the system in about 12 years ago to replace a very efficient home made GWHP installed when the house was built in 1955. Access to a dedicated well and an easy way of getting rid of the water when the GWHP was done with made the economics work better. The water comes out of the ground at between 52* and 54* year around. Another key is that the community has a municipal water utility and the electricity costs are low.

I think GWHP make sense when many of the following are present:

1. Easy access to water. Like an existing well with adequate capacity.

2. Easy way to get rid of the water.

3. Low electricity rates.

4. High natural gas, propane, or oil costs.

5. Strong cooling loads.

GWHP provides the ability to heat hot water in the summer "for free". So a restaurant, bar, or supper club in the country on a lake, river, or large pond would be a perfect candidate for a GWHP.

From my experience since 1955 ... a GWHP isn't a cheap date on the front end, but it works and I like it.

 

[theoldwizard1]

We have a WaterFurnace(r) in a house 25 miles NW of Green Bay (WI). The WaterFurnace came standard (I think) with electric resistance backup. Electric resistance backup is inexpensive to install in the unit and is ready anytime you need it. While there is very little you can do if the POCO fails to provide you power, there are a number of things that can go wrong with a GWHP system that makes having the backup a good idea.

So that everyone understands my position, I think a back up for any heat pump system (especially in a cold climate) IS a GOOD IDEA ! I just think electric resistance is nor a good choice because power outage are probably more common than any other failure of a heat pump system, air sourced or ground water sourced.

I think GWHP make sense when many of the following are present:

1. Easy access to water. Like an existing well with adequate capacity.

2. Easy way to get rid of the water.

The vast majority of geothermal heat pumps systems being install today have vertical wells. The heat transfer pipe is a looped at the bottom of the well, so never have to "get rid" of water. You can not share a drinking water well with a geothermal loop, and abandoned wells likely are insufficient diameter (although it might be cheaper to re-drill an existing well).

3. Low electricity rates.

4. High natural gas, propane, or oil costs.

#4 can easily offset the lack of #3 !

5. Strong cooling loads.

Pay off is quicker, for sure. High heat costs (propane or oil and a long heating season) are another factor in going geothermal.

From my experience since 1955 ... a GWHP isn't a cheap date on the front end, but it works and I like it.

Getting cheaper, but far from cheap !

 

[05r50]

I have a 17 year old house with geothermal. House was built that way and is bout 2800 sq ft and all electric.

Other than propane this is my only choice. I don't have wells, I have a closed loop system that cycles out through my yard..

The unit failed in spring of 2014 and had to be replaced.. I looked at switching to propane then but didn't because of the propane cost last year and the fact that my house would need a retrofit for a gas flue..

New unit cost just over $13k, and I got a big tax break for the expense, like $4k. My elec bill averages bout $430/month year round and winter this year has been brutal. I think that is reasonable for all electric home.

Payback? Not sure if it mattered in my case.. Really didn't have much choice.

 

[Dick in Wisconsin]

I have a 17 year old house with geothermal. House was built that way and is bout 2800 sq ft and all electric.

What kind of a system did you have? What did you replace it with?

Where do you live?

 

[05r50]

Mine was a water furnace and I replaced with same. Has the backup heat pump and I also added an upgraded filter box.

The original was never a service problem. It was very reliable. Just had a failure in the compressor and corrosion in the loop coil.

I am in Ohio.

 

[jwvess00]

Hi there!

My house was originally built in 1990 with a geo system. I bought my house in fall 2013. February 2014 I had to have the whole system replaced but kept the existing wells. I wish I had known the system was junk when I bought the house, but that's one of a few things my home inspector missed.

I'm not sure how many wells are in the system or how deep they are. I am in Paris, KY which is 15-20 miles north of Lexington. The installer thought there were probably 3 vertical wells 150'ish deep. It's a closed loop system.

I just checked, and my current loop temperature is 32 entering. 27 leaving. Weather dot com says it's 33 degrees outside, with several inches of snow still on the ground.

I considered replacing it with an air source heat pump, since it would have been cheaper, but the highest-end air source system was not so much cheaper that it made me decide to go that route. Beyond that, having geo is a selling point should I decide to someday sell the house.

I have a 3 ton system in a house where the system is heating about 1600 sq. ft. all on the first floor There is an upstairs in my house (900 sq. ft. finished attic) with its own air source heat pump. I don't use that space for much more than my 11 year old's play area. I usually keep the heat pump turned off upstairs since we almost never go up there except for some time on the weekends.

This winter I've seen the electric auxillary heat come on what seemed like quite a bit, but we've had plenty of single-digit degree days. My electric bill, at $0.10/kWh, was a bit under $300 for my all-electric house for a rather frigid February.

My house sits on a crawl space that needs some work. It was originally insulated by paper-faced fiberglass bat, but the paper was facing the ground (the wrong direction). It was not in good condition, so I removed it all. I have not done anything to re-insulate the crawl space so I know I'm losing a decent amount of heat that way. On the upside, my pipes didn't freeze when it was nearly -20 outside... It's on my list of Things To Do to fix the crawlspace insulation situation somehow.

Still, my electric bill with the new geo system seems to be less than my old house, with its less efficient air source system -- even though my old house was 200 feet smaller, and had an electric provider with cheaper electricity. I'll call that a win.

 

[theoldwizard1]

I have a 17 year old house with geothermal. House was built that way and is bout 2800 sq ft and all electric.

Other than propane this is my only choice. I don't have wells, I have a closed loop system that cycles out through my yard.

I would be very curious to know what your inlet and outlet water temperatures are, especially in winter.

If your inlet temperature is below 50F, your loop was designed or installed incorrectly.

If your outlet temperature is too low that would also be a problem.

Both of these drastically affect performance and cost of operation. If you don't have temp probes, pay a plumber to install them.

 

[theoldwizard1]

I just checked, and my current loop temperature is 32 entering. 27 leaving. Weather dot com says it's 33 degrees outside, with several inches of snow still on the ground.

If those numbers are accurate, you have a serious problem with your well design. Most heat pump start loosing efficiency below about 45F. 32F inlet is ridiculous ! (The temperature of the earth, below 15-20' is a near constant 50-60F. Your wells should be providing you that at your inlet.)

Hire an experienced geothermal company and have them review the entire installing, especially the well(s).

 

[JimL]

I would be very curious to know what your inlet and outlet water temperatures are, especially in winter.

If your inlet temperature is below 50F, your loop was designed or installed incorrectly.

If your outlet temperature is too low that would also be a problem.

Both of these drastically affect performance and cost of operation. If you don't have temp probes, pay a plumber to install them.

I am not sure where you get your info, a loop with glycol or some sort of antifreeze will run down to 15 degrees or so. Water furnace units have a dip switch to change, 30 degree freeze protection or 15 degrees...

 

[toplessHO]

I looked up the median temp for your location and its 57*. Are you sure your loop temps are that low? if so they arent providing the heat exchange thats available to you.Have you had the loop flow tested?

Hi there!

My house was originally built in 1990 with a geo system. I bought my house in fall 2013. February 2014 I had to have the whole system replaced but kept the existing wells. I wish I had known the system was junk when I bought the house, but that's one of a few things my home inspector missed.

I'm not sure how many wells are in the system or how deep they are. I am in Paris, KY which is 15-20 miles north of Lexington. The installer thought there were probably 3 vertical wells 150'ish deep. It's a closed loop system.

I just checked, and my current loop temperature is 32 entering. 27 leaving. Weather dot com says it's 33 degrees outside, with several inches of snow still on the ground.

I considered replacing it with an air source heat pump, since it would have been cheaper, but the highest-end air source system was not so much cheaper that it made me decide to go that route. Beyond that, having geo is a selling point should I decide to someday sell the house.

I have a 3 ton system in a house where the system is heating about 1600 sq. ft. all on the first floor There is an upstairs in my house (900 sq. ft. finished attic) with its own air source heat pump. I don't use that space for much more than my 11 year old's play area. I usually keep the heat pump turned off upstairs since we almost never go up there except for some time on the weekends.

This winter I've seen the electric auxillary heat come on what seemed like quite a bit, but we've had plenty of single-digit degree days. My electric bill, at $0.10/kWh, was a bit under $300 for my all-electric house for a rather frigid February.

My house sits on a crawl space that needs some work. It was originally insulated by paper-faced fiberglass bat, but the paper was facing the ground (the wrong direction). It was not in good condition, so I removed it all. I have not done anything to re-insulate the crawl space so I know I'm losing a decent amount of heat that way. On the upside, my pipes didn't freeze when it was nearly -20 outside... It's on my list of Things To Do to fix the crawlspace insulation situation somehow.

Still, my electric bill with the new geo system seems to be less than my old house, with its less efficient air source system -- even though my old house was 200 feet smaller, and had an electric provider with cheaper electricity. I'll call that a win.

 

[jwvess00]

Hello,

I looked up the median temp for your location and its 57*. Are you sure your loop temps are that low? if so they arent providing the heat exchange thats available to you.Have you had the loop flow tested?

I pulled those loop temperature numbers from the iGate thermostat. Set the system to off, go into the insaller menu, and read the numbers. I assume they're accurate but I'm no HVAC guy so I don't know much about the data it can give. I think it can give flow rate but I'm not sure.

I was concerned about low loop temperature too but the foreman on the job wasn't too concerned. They did a great job on the mechanical installation but I was not impressed with their "master technician". He missed some things I thought he should have caught during installation and startup instead of me finding after the fact. I have a feeling he was more interested in wrapping things up and leaving than he was making sure the system started properly. They did a beautiful job of the mechanical installation but their startup left a lot to be desired.

The system is a ClimateMaster Tranquility 30, and just about exactly1 year old. The wells, as far as I know, were installed in 1990 when the house was built. I wish I knew more about the wells, but I bought the house in 2013 and the previous owners didn't build the house either. I do know they're closed loops. I know who first owned the house and suspect he'd be willing to help if I asked (he's a local real estate agent, and was the selling agent for my house so he profited from my buying the house), but I dobut he'll remember details like that 25 years after the fact.

The system is filled with glycol so sub-32F shouldn't be a problem.

I may email my installer and find out what's expected. I'd hate to have to spend several grand more for new loops but I'd rather the system work right, too.

Thanks for any thoughts and advice. I didn't mean to hijack the thread but I think it's useful information for geo or potential geo owners.

 

[volleyball]

You may want to find out if your wells were grouted or not. That can make a big difference. I think there is a way to determine your wells depth. I cannot remember what it is. One way I do know is that the well driller has to have the information. It gets recorded. Maybe any driller has access to the files.

 

[theoldwizard1]

I am not sure where you get your info, a loop with glycol or some sort of antifreeze will run down to 15 degrees or so.

Sure it will.


And your efficiency will go right down the toilet !

 

[theoldwizard1]

I was concerned about low loop temperature too but the foreman on the job wasn't too concerned.

Of course not ! It didn't leak and heated and cooled when it was requested.

But then again, the foreman is not paying the monthly electric bill !

 

[theoldwizard1]

I looked up the median temp for your location and its 57*. Are you sure your loop temps are that low? if so they arent providing the heat exchange thats available to you.Have you had the loop flow tested?

Exactly the point I am trying to make !

 

[JimL]

Sure it will.


And you efficiency will go right down the toilet !

I don't think you get it. Pump glycol thru your loop for 3 months straight. Your ground started at say 55 degrees, after 3 months of pulling heat out of that ground, how warm do you think its gonna be? You think that running freezing cold water through the ground for months on end isn't going to freeze it, you're nuts!

 

[theoldwizard1]

I don't think you get it. Pump glycol thru your loop for 3 months straight. Your ground started at say 55 degrees, after 3 months of pulling heat out of that ground, how warm do you think its gonna be? You think that running freezing cold water through the ground for months on end isn't going to freeze it, you're nuts!

I disagree ! Go deep enough and the ground temperature will only change a few degrees close to your pipe. 12 months a year.

Read this paper by th American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.

The simple thing to note is that their design goals shown in the graph below indicate the LOWEST inlet water temperature should be about 32F !

Personally, I would want my inlet temp to be around 55F. Increasing your inlet temperature is a matter of burying your loop deep enough and making your loop long enough

 

[pseudorealityx]

That is a very strong opening statement, but I do agree that mini-splits are very cost effective, especially in areas where you do NOT have outside temperature extremes.

Some of the SE states have now mandated that all new public building uses geothermal heat pumps, because the operational costs are so low and they have long cooling seasons).

I've not heard of this. For awhile, many governments were requiring LEED accreditation, but forcing Geothermal is just stupid due to climatic and geological issues.

 

[pseudorealityx]

I don't think you get it. Pump glycol thru your loop for 3 months straight. Your ground started at say 55 degrees, after 3 months of pulling heat out of that ground, how warm do you think its gonna be? You think that running freezing cold water through the ground for months on end isn't going to freeze it, you're nuts!

He's not nuts... if anyone is in this thread, might want to find a mirror. A couple of things...


1) The discharge after the heat pump pulls heat out is (example) ~40 degrees. No matter how much 40 degree glycol you pump through ground, it's never going to make the ground colder than 40 degrees. That's like trying to boil water (212 degrees) using 200 degree hot air as your heat source.

2) If your ground freezes 6-7' underground, which I kinda doubt in Indiana, then your geo field was designed incorrectly if the loops are at that depth. That's why you bury them deeper, or put in vertical wells.

3) Scale is your friend here. 200' down, the temperature IS pretty darn constant. Even pulling heat out of ground for months on end, if the field is sized correctly, you will slowly reduce your delta T's during the winter months, but not enough make your system not operate.

4) My company has done some large scale geothermal. We've got a LEED Certified VA hospital in Virginia that runs 100% geothermal, zero backup heat, no boiler tied into the ground loop, nothing.

 

[Jackfre]

TOW1, my comment about the demise of tax credits and the end for geothermal is, I think, correct for residential. Your comment about the commercial use makes sense but that it because they can control the water temp of a closed loop so much better through the use of cooling towers or boilers to preheat the water or whatever fluid they are running. That is commonly done in big buildings. The real trend in commercial is the VRF mini-splits. High rises are going this way because a building owner can have a floor by floor system. If that floor turns over and is remodeled, a new or reconfigured system can be installed for that floor. Great option for a developer and for the tenant. This has been going on for several years and successfully.

In ground heat transfer is based upon a Reynolds number. It varies by temp and moisture. Back in the 70's, when I was doing the pool systems we also used Solaroll for inground piping. We would take Ditchwitch and dig a deep trench slide the SR panel into the ground and backfill with sand. I would work fine, for a short while, and then poor heat transfer. We then put drip irrigation over it to keep the sand wet and performance improved.

Also, your idea of going deeper with the ground loops is correct, but there is a limit to the cost effectiveness of that too. There are many stories (the true ones) where a geothermal system did in fact freeze the ground.

Given that it only takes about 55* to make these things sing in the heat mode, it is also not the worst idea to pair a system up with a boiler as they do in commercial. Pricey, but it would probably be only for short periods. Heat Transfer Products and Heat Flo make some nice SS tanks with internal HX. If my ground loop proved inadequate that is one way to fix it.

 

[Jackfre]

Hot Rocks! Another anecdote. Out Reno way, there was a direct Geo job called the Hot Rocks. It was a dry but high temp field. What they did there was inject water into the rock bed, heat it and extract it. It worked great for several years and then they cool capped the field and the project was done. There was still plenty of heat down there. The problem was the Reynolds number and in ground heat transfer was so poor that the field could not recharge. That was a long time ago. I do not know if they ever resurrected that or not.

 

[theoldwizard1]

I've not heard of this. For awhile, many governments were requiring LEED accreditation, but forcing Geothermal is just stupid due to climatic and geological issues.

There was a dirty jobs episode about 5-7 years ago where they were boring wells and insert pipe followed by grout for a new public building (school ?). I don't recall if it was SC or NC, but it is a GREAT IDEA given the cooling load they have in that area !


Location, location, location.

 

[theoldwizard1]

3) Scale is your friend here. 200' down, the temperature IS pretty darn constant. Even pulling heat out of ground for months on end, if the field is sized correctly, you will slowly reduce your delta T's during the winter months, but not enough make your system not operate.

Absolutely.

Looking at some charts, north of the 45th parallel, is not recommended for geothermal. My only guess is the ground near the surface (20-40' down?) get so cold that it heat gained from 200' down is lost. also the pipes leading to the heat pump it self would have to be about 7-10'. I guess they could insulate those pipes to try and keep the water temp above 50 before it got the the heat pump heat exchanger.

4) My company has done some large scale geothermal. We've got a LEED Certified VA hospital in Virginia that runs 100% geothermal, zero backup heat, no boiler tied into the ground loop, nothing.

But I bet a hospital has a BIG backup generator !!

 

[theoldwizard1]

Your comment about the commercial use makes sense but that it because they can control the water temp of a closed loop so much better through the use of cooling towers or boilers to preheat the water or whatever fluid they are running.

But that is THE WHOLE POINT ABOUT GEOTHERMAL ! The mass of the earth is so huge, that properly sized heat transfer loops do NOT REQUIRE COOLING TOWERS OR BOILERS !

True, most commercial building built until now use cooling tower and/or ponds for their A/C. Simple, proven technology and I admit, cheaper than geothermal, IF YOU HAVE THE SPACE. Again, it is all about your location.

If I was building a single purpose commercial building in Southern FL, I would demand geothermal wells ! By the end of the summer, cooling tower water and/or ponds are going to be close to 90°. Ground water from 200' down will still be about 55° !

The real trend in commercial is the VRF mini-splits. High rises are going this way because a building owner can have a floor by floor system. If that floor turns over and is remodeled, a new or reconfigured system can be installed for that floor. Great option for a developer and for the tenant. This has been going on for several years and successfully.

Overall efficiency is less, but the flexibility you mentioned is very important for rental purposes.

Also, your idea of going deeper with the ground loops is correct, but there is a limit to the cost effectiveness of that too. There are many stories (the true ones) where a geothermal system did in fact freeze the ground.

Possible, yes. At what depth ? I would also say that (for residential application) if your inlet water is below 32°, then the field was not properly designed/installed.

Given that it only takes about 55* to make these things sing in the heat mode, it is also not the worst idea to pair a system up with a boiler as they do in commercial. Pricey, but it would probably be only for short periods. Heat Transfer Products and Heat Flo make some nice SS tanks with internal HX. If my ground loop proved inadequate that is one way to fix it.

I can not argue with your last statement !

If I was building a house that was going to be heated and cooled by a geothermal heat pump, the heating contractor's contract would have a "performance clause" stating expected inlet water temperature for a 5 year period, with appropriate penalties !!

 

[JimL]

He's not nuts... if anyone is in this thread, might want to find a mirror. A couple of things...


1) The discharge after the heat pump pulls heat out is (example) ~40 degrees. No matter how much 40 degree glycol you pump through ground, it's never going to make the ground colder than 40 degrees. That's like trying to boil water (212 degrees) using 200 degree hot air as your heat source.

2) If your ground freezes 6-7' underground, which I kinda doubt in Indiana, then your geo field was designed incorrectly if the loops are at that depth. That's why you bury them deeper, or put in vertical wells.

3) Scale is your friend here. 200' down, the temperature IS pretty darn constant. Even pulling heat out of ground for months on end, if the field is sized correctly, you will slowly reduce your delta T's during the winter months, but not enough make your system not operate.

4) My company has done some large scale geothermal. We've got a LEED Certified VA hospital in Virginia that runs 100% geothermal, zero backup heat, no boiler tied into the ground loop, nothing.

You're lost as well. You're TAKING HEAT OUT OF THE GROUND AND PUTTING IT IN THE HOUSE. Eventually you're gonna run out of heat in the ground around the loop lines, it will freeze, I know it will, I looked at 3 geo's last week that all had below freezing loop temperatures. All done by different loop companies, only one was one we did and we had the company Water Furnace recommends do the loop. They do hundreds every year.

Say you lose half a degree a day, it don't take long and you're below freezing.


Geo shines in cooling, not so much in heating.


Geo's really don't shine that much in heating, they really perform in cooling.

 

[pseudorealityx]

You're lost as well. You're TAKING HEAT OUT OF THE GROUND AND PUTTING IT IN THE HOUSE. Eventually you're gonna run out of heat in the ground around the loop lines, it will freeze, I know it will, I looked at 3 geo's last week that all had below freezing loop temperatures. All done by different loop companies, only one was one we did and we had the company Water Furnace recommends do the loop. They do hundreds every year.

Say you lose half a degree a day, it don't take long and you're below freezing.


Geo shines in cooling, not so much in heating.


Geo's really don't shine that much in heating, they really perform in cooling.

Nevermind... it's not worth arguing over.


Real quick.... you're NEVER going to run out of heat in the EARTH if you size your loop appropriately for the geological conditions you have. NEVER NEVER NEVER.

 

[JimL]

If you have 8 miles of loop maybe yes..

 

[theoldwizard1]

Nevermind... it's not worth arguing over.


Real quick.... you're NEVER going to run out of heat in the EARTH if you size your loop appropriately for the geological conditions you have. NEVER NEVER NEVER.

TRUE !

If you have 8 miles of loop maybe yes..

Considerably less. Maybe 500-1000 feet 20' below the surface. I all depends on the load.


Maybe you will believe Wikipedia

Depending on latitude, the temperature beneath the upper 6 metres (20 ft) of Earth's surface maintains a nearly constant temperature between 10 and 16 °C (50 and 60 °F), if the temperature is undisturbed by the presence of a heat pump. Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat from the ground. Heat pumps can transfer heat from a cool space to a warm space, against the natural direction of flow, or they can enhance the natural flow of heat from a warm area to a cool one. The core of the heat pump is a loop of refrigerant pumped through a vapor-compression refrigeration cycle that moves heat. Air-source heat pumps are typically more efficient at heating than pure electric heaters, even when extracting heat from cold winter air, although efficiencies begin dropping significantly as outside air temperatures drop below 5 °C (41 °F). A ground source heat pump exchanges heat with the ground. This is much more energy-efficient because underground temperatures are more stable than air temperatures through the year. Seasonal variations drop off with depth and disappear below 7 metres (23 ft) to 12 metres (39 ft) due to thermal inertia. Like a cave, the shallow ground temperature is warmer than the air above during the winter and cooler than the air in the summer. A ground source heat pump extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling).

Geothermal pump systems reach fairly high Coefficient of performance (CoP), 3 to 6, on the coldest of winter nights, compared to 1.75-2.5 for air-source heat pumps on cool days. Ground source heat pumps (GSHPs) are among the most energy efficient technologies for providing HVAC and water heating.

 

[pseudorealityx]

Here's McQuay's Geothermal Design Guide:

http://www.15000inc.com/wp/wp-content/uploads/Geothermal-Heat-Pump-Design-Manual.pdf

It includes sections on long term effects.

 

[JimL]

Thats all fine and dandy, but I guarantee you that you can freeze the ground where your loop is. And once it freezes, you lose even more efficiency, thermal conductivity is gone. Sure if you dig 20 feet down and put the loop in that far it may be better than 6' down. But I sure have never seen anyone dig a loop that deep.

Its really no different than the hacks that sink coils of tubing in a lake with concrete blocks. Ive seen those build enough ice that they float to the surface. You can freeze water in a lake, you can freeze it underground...

 

[volleyball]

Seems like they don't build the right in Indiana. Pro companies or not. Seems the ground there is made up of material that transfers heat poorly. Maybe the homes are poorly insulated and putting a larger than designed load on the system.
For those locations, maybe digging a second well and alternating there use will solve the problem. Not a fault of geo but the location.
I had my wells dug deeper than calculated as you cannot easily expand your holes. A little more upfront cost but I got a deal as the driller was all set up, just had to go further than originally planned.

 

[Jackfre]

Yes it works, but at what cost. Build the house correctly and put it he dollars into the envelope and you can heat the house by rubbing your hands together. Doing an average to average plus build and throwing a geo at it, at its high cost doesn't make sense. Reduce the load and you have a lot of efficient options.

TOW1 when I was speaking of the boiler/ cooling tower applications I was thinking high rise and hotels and such. There are limits in most commercial properties to the space you can access and that limits field size. In fact in many of those buildings they are using the water source hp, with no geothermal component. Compact design and excellent zoning

 

[theoldwizard1]

Thats all fine and dandy, but I guarantee you that you can freeze the ground where your loop is. And once it freezes, you lose even more efficiency, thermal conductivity is gone. Sure if you dig 20 feet down and put the loop in that far it may be better than 6' down. But I sure have never seen anyone dig a loop that deep.

You are correct ! That is why they use wells !!!

Once the loop is sent to the bottom, the well is grouted. The grout handles the heat transfer from the pipe to the earth.

 

[backintheday]

Well I was planning on using geothermal to heat my new shop but now you guys got me rethinking my original plan. I live in a cold climate, we have 5-6 months winters, it's not uncommon to see -30s for a few weeks and I have been told the frost can go go down to 8'. I was thinking of expanding the ground loop but now I'm scared to take the plunge. I can do all the work myself so it won't cost me much. I am using SIPs so the building should be efficient. I might just go with propane and use a wood stove to help keep the propane cost down. I don't want my inlet temps to drop to the point the system doesn't work when we're in month 6 of a long winter.
Thanks for all the info in this thread.

 

[MushCreek]

I briefly considered geo for our new house in SC, but couldn't justify the cost. We wound up using Mitsubishi mini-splits, good to -5 F. Our house is small (1400 sq ft plus a full basement) and very tight and well insulated. The A/C in July added $20 to our total electric bill. In the very coldest months, it adds about $60, but that's only about 2 months out of the year.

 

[volleyball]

Mini splits are a big upgrade over window units but they are basically the same thing. And you need an open floor to use them properly or have a bunch of units.

 

[MushCreek]

Mini splits are a big upgrade over window units but they are basically the same thing. And you need an open floor to use them properly or have a bunch of units.

Sorry, but saying a mini-split is basically the same as a window unit is like saying a Ferrari is basically the same thing as a Fiat.

1) Mini-splits are split systems, unlike a window unit.

2) Quiet- REALLY quiet. You can't hear my indoor units unless you really try. Same for the outdoor unit.

3) 26 SEER, which blows away just about any other system.

4) They can have multiple heads, giving you MORE temperature control in individual rooms than a central system. They also have ducted versions.

5) The heads can be configured to mount in a wall or ceiling, making them indistinguishable from a conventional central system.

6) My interior units can be set to sense the warmest (or coldest) part of a room and direct the air towards it.

7) They have a dehumidify mode, which dehumidifies without having much affect on the room temperature.

Not to start something; I just wanted to set the facts straight. My minis blow away (pun intended) any central system I've ever seen.

 

[pseudorealityx]

If you don't need ventilation of filtration, multi-zone mini-splits are very hard to beat.

I think what volleyball was saying is that the process is the same. Both are direct expansion, air cooled refrigerant based systems. But as you said... Ferrari vs. Fiat.

 

[volleyball]

There has been a lot of Ferrari Fiat collaborations so it seems you agree.

And all the points against it really are what a window unit does, only better at a much more expensive price.
A chevy and a caddy on the same chassis is the same car, one just nicer at a much higher price.
If you hate window units, you dislike splits. It is the only logical progression.
I don't hate window air, don't like them either. Splits are less bad. I see them as predominant units in the Orient but that environment is something I no longer have to deal with.