DIY Geothermal?

curiouscarbon

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In my opinion (building for homes for 34 years) make the house airtight, insulate insulate insulate and then you can heat your house with 2 light bubs and a fart....
lol! what's the cost ratio of fart to electricity? 🤔 thank you for your insights. very interesting about the frequency tuning of slab insulation. rad. and angled outwards boreholes for increased thermal transfer. cheers!

have you used vacuum insulated panels in any installations?

they have more succeptibility to damage (puncture) but have R22-30 per inch.. have seen it used in alaska
 

Partimewages

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Anyone interested?
YES!
I installed my first geothermal system in 1990. I'm from Ohio and geothermal was advertised in the farm magazines in the state. I'm sure it was else where also. Worked on all types of water source heat pump systems. Believe me there are all different designs. In 1992 we decided to try and become a 100% geo HVAC dealer with the goal of 5 years to do that. Granted we were small but to restrict ourselves to one type is a little scary when it's feeding you. By 93 we were only installing and servicing geo. Hundreds of installations in my background. I'm sure I haven't seen it all but pretty close. There's quite a bit of engineering that goes in to the system.
I will help this thread as I can. Be warned sometimes I can seem like I have strong opinions but I mean no disrespect to anyone. Due to health it's been a couple of years since I personally installed anything but the phone still rings regularly for consult. Some things have changed over the years but the engineering is the same.
There are basically two types of systems.

1. Pump and dump. Use ground water to fuel the system. Don't go to green on me here it has its place. If interested we can discuss further.

2. Closed loop water source. This is what most of the market is. Drilling holes, laying pipe, loops in a pond.

3. Commercially there's a third. Boiler tower loop. Used in schools office buildings and the like. This is not geothermal. It is moving heat around the building. Adding and rejecting heat from a source other than the ground.

Sorry for the long post but this is one of my favorite topics to talk about!
 

curiouscarbon

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Sorry for the long post but this is one of my favorite topics to talk about!
Thank you for sharing your experience in this field (ha ha get it geothermal fields) 🤪 definitely please share more if you want!

The core of the earth is giving off trillions of BTU free, just waiting for us to pump pump pump it up!

Geothermal is fricking neat!
 

Bob B

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@Mike 604 .... appreciate your input.
I think we all agree that the best bang for the buck is to do as much as possible to make a house tight and well insulated.
We don't all have the luxury of building a new house that is designed from the ground up to be energy efficient, however.

My experience with geothermal is from commercial applications where water source heat pumps were installed in conjunction with a geothermal field. One of those buildings was a new building and others were a retrofit to an existing building.
Both of the systems I worked with worked very well and were saving a TON of money over traditional commercial HVAC.

I'm a little confused over the term "ground source". Does that indicate that the well is actually drilled to get down to ground water? Seems like the term for heat pumps indicating ground source and water source may be used interchangeably ..... are they actually are the same thing?
Or maybe ground source is just another term for geothermal?

Most mini splits like to advertise their seer rating .... but the EER rating will be a lot lower. A mini split that has a SEER rating of 24 will probably only have an EER of around 14.

I have seen some of the water source heat pumps advertising an EER rating of over 40 which is a huge improvement for cooling efficiency over an air cooled mini split.

Here's an article about the difference between EER and SEER. https://www.pickhvac.com/faq/seer-vs-eer/
 

Mike 604

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I can only provide feedback on the new home builds that I have done. Not an expert by any means.
The short term cost of doing an airtight home build is higher than a traditional house, agree.
But here in the Pacific North West it is required by our jurisdictions having authority on all new builds and on mayor renovations to build air tight to a certain air tight ness level. New build here needs to achieve a level of 1.6 , our homes test are at or below .8.
Here just North of Seattle the utility bills for a 3000 sq ft is typically $180 a month.
Air tight house that we did was $34, so if we check the cost over a 15 year period we have a cost diff of 25k.
The cost to make the house air tight, add blanket of 2 "exterior insulation cost was around 15k.
Client felt it is worth while, as the client is more comfortable in the house, it is quieter and long term cheaper to own.

Seattle and Vancouver are now stating that natural gas will be phased out of a new build in the next 5 years.
No cooking, heating, bbq or patio heaters with gas. The days are numbered.

Forgot to mention that all new home builds have to have an HRV or an ERV installed in order
to remove excess moisture and control the RH of the house. HRV and ERV provide fresh air into the 24/7.

Have not used the evacuated vacuum tubes for hotwater but have a job where this has been specified by the client and mechanical
engineer. House will be net zero build.

Ground source vs water source sorry for not being clear.
Ground source I mean by either having bore holes into the ground, avg hole depth has been 275 ft.
The other ground source is a horizontal loop field, (slinky pulled sideways) we excavted 6 ft deep x 60' x 45' if my memory serves me correctly .
The water source which were not allowed to do was to be set into the ocean.

Will read the link on the heat pumps when I get home., Thanks for the link Bob B

Always time to learn.
 
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toms

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Forgot to mention that all new home builds have to have an HRV or an ERV installed in order
to remove excess moisture and control the RH of the house. HRV and ERV provide fresh air into the 24/7.

I would rate this as essential in any house i’m going to be living in.
 

Bob B

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In commercial buildings, there was always a requirement for a certain amount of outdoor air. Sometimes that was specified as a % and sometimes there was an actual CFM of outdoor air required .... sometimes the amount of outdoor air was determined by the CO2 levels in the area being served.

Almost all the new stuff had some sort of heat / desiccant wheel ... which sometimes had some pretty complex control requirements for the speed of the wheel, etc. On a large commercial building, there used to be a gazillion exhaust fans .... in an energy retrofit, those would be replaced with more sophisticated devices that transferred heat as well as humidity. In different seasons, the transfer may be the opposite from others.

Energy engineering can result in a very complex overall system ... but there were getting to be some pretty standard "tools" in the box.
 

Partimewages

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Geothermal is energy/heat from the ground. Many call ground source heat pumps geothermal but that is not really where the energy comes from. Drilled loops or horizontal loops are considered ground source closed loop systems. The heat they recover or transfer is from the sun.
True geothermal is only available in certain areas where the crust is thin. I read an article some years ago about Iceland or Greenland having true geothermal piped around to houses for heat. That's real geothermal!
I agree that the tighter you build the better the efficientcy of the house is. The HRV/ERV system is critical for the health of the occupants and should be a requirement. But requirements is a whole other topic.
 

Bob B

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Geothermal is energy/heat from the ground. Many call ground source heat pumps geothermal but that is not really where the energy comes from. Drilled loops or horizontal loops are considered ground source closed loop systems. The heat they recover or transfer is from the sun.
True geothermal is only available in certain areas where the crust is thin. I read an article some years ago about Iceland or Greenland having true geothermal piped around to houses for heat. That's real geothermal!
I agree that the tighter you build the better the efficientcy of the house is. The HRV/ERV system is critical for the health of the occupants and should be a requirement. But requirements is a whole other topic.

Maybe I've a been mis-using the term geothermal ..... I was under the impression that using the constant cool temperature of the ground was geothermal .... but maybe true geothermal is just tapping into the hot core of the earth.

Guess I should change the title of the thread.
 

Bob B

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Hmmm .... this article uses the term both ways .... which is more like I was thinking about it .... I'm confused.


But, who trusts the government to get it right?
 

Partimewages

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None of what I said needs to be interpreted to any great extent. The ground I walk on is central Ohio. At a 5' depth in late January it's about 40 degrees late July it's about 70. Even 50' deep there's a difference from the affect of the top side weather. Go further north it's slightly cooler further south warmer. This is why I disagree with someone about just putting pipe in the ground and circulating water for heat and cool. The amount you need to have to actually maintain temperature is great and likely unaffordable. There's all kinds of engineering that can be used to figure out how many BTU's you need to transfer to make it work.
I'm enjoying talking about geothermal, ground source, water source heat pump systems!
 

newbostonconst

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I have done 2 Geo houses myself in lower Michigan. First one's field was a horizontal loop of 5000 ft of pex four feet deep. Had 2 units, one was water to water and other a standard forced air geo unit. The house also had heated floors so could be heated by geo or natural gas water heater. Heating the house with natural gas was 80% of the geo running cost. Water to Water unit only lasted 4 years before needing repeated repairs so we just stayed with NG heating of the floors. That was back in the early 2000's and many geo units were junk, lots of cost for units that didn't last.

Second house built in the last 4 years and is similar but doing pump and dump. Again 2 units, a water to water and forced air....and again the NG heating cost to run was 80% of the geo cost. So in winter we use NG but in summer we do some crazy stuff. Hot water is heated with the geo water to water unit and the cold side cools the heated floors. The forced air unit is ran as a pump and dump but first the 50 degree well water is ran through the floors to get to almost 70 degrees and then goes to the forced air geo unit and is heated to almost 110 degrees before being sent to the sprinkler system to water the grass. If it is hot out the grass needs to be watered so it is "green" ;)

This new house is R40 walls and R80 roof, about 5600 sqft of exposed sqft and 7000 sqft total floor area... ACH was .78 for the whole house. We have 10k solar and have yep to pay an electric bill. NG in winter is under $100 a month, usually cost $40 month to just heat water for showers with NG....have 5 to 9 people daily living in the house.

For the first 2 years tried just running the sprinkler water through the floors to cool the house but the runtime was long (like 20 hours a day) and in the end used a lot of water so switched to the current loop this year and have been very happy.
 

acdoctor

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Years ago I built and used a passive geo unit in my home. I ran 40 ft to the well and with very insulated pex to the water line then 50 feet down into the water and 50 ft back up in the water with copper. I used a inverter fan used in walk in freezers. A taco pump 60 watts. It cooled the air well but didn’t dehumidify. Here in Arkansas that is important. Most dehumidifiers are not very energy efficient. I can run a mini split for less than a dehumidifier. I used it for a couple of years.
 

curiouscarbon

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Years ago I built and used a passive geo unit in my home. I ran 40 ft to the well and with very insulated pex to the water line then 50 feet down into the water and 50 ft back up in the water with copper. I used a inverter fan used in walk in freezers. A taco pump 60 watts. It cooled the air well but didn’t dehumidify. Here in Arkansas that is important. Most dehumidifiers are not very energy efficient. I can run a mini split for less than a dehumidifier. I used it for a couple of years.
thanks for sharing your experience!

that’s a pretty neat sounding solution for efficient comfort🛠👍
 

Bob B

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Yes .... all experiences are welcome on this thread .... doesn't matter if it was a fail or a dream come true.

Thanks to all for the input.
 

redalertdt

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I did a DIY geothermal for a small house in Maryland. In my opinion with equipment available for residential geothermal etc. you really have to take a good look at a new minisplit heatpump (eg. mitsuibishi) that can heat to -24F (not sure the COP/curve maybe 3-4 COP?). Also in my experience they don't include most pumps etc. in the efficiency numbers for the Geothermal units. Horizontal loop is very diy friendly, but with the innovations in tech that the newer air-air heat pumps have in them it is really hard to justify geothermal in most climates in the USA. I think commercial buildings probably use chilling towers and run separate hot/cold lines throughout the building for different uses. I imagine they would be setup a lot different than a house (eg. fridge is working against ac).

The more interesting thing to me would be to do air to water with separate storage tanks for hot/cold and multiple uses in the house. The only one I have seen was the chiltrix, but it seems like it is very finicky and faulty.
 

Bob B

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I had a kinda crazy idea once to build a very large insulated storage tank with coils in the bottom of it.

When it gets very cold in the winter ... take the top off and blow the cold air down inside and add a new layer of water that turns to ice every day til its filled up with ice.

Don't know how big that tank would have to be to provide cooling for the summer.
 

Partimewages

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I had a kinda crazy idea once to build a very large insulated storage tank with coils in the bottom of it.

When it gets very cold in the winter ... take the top off and blow the cold air down inside and add a new layer of water that turns to ice every day til its filled up with ice.

Don't know how big that tank would have to be to provide cooling for the summer.
Really big! 1 btu changes 1 pound of water 1 degree. How big is your AC unit? 2 ton is 24000 btu per hour. 1 gallon of water is approximately 8.33 pounds.
When water goes through the phase change it gains or loses 144 BTU's so there is a tremendous amount of heat transfer in that process. If your 2 ton AC runs 10 hours in a day it would move 240000 BTU's. If you changed the water temp by 10 degrees say 40 degrees up to 50 degrees. Cooling the house or adding heat to the tank. You would need about 3000 gallons of water to keep your house cool.
The farmer I did my first system with built a in ground tank under his two car garage that would hold about 30000 gallons. He used rain water into the tank to help with the transfer of the loop for heating and cooling. Worked okay if you could keep the leaves out of it.
Many commercial and industrial customers have ice building storage tanks. They make ice in off peak times and then use it during the day to save on peak rates.
 
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