Ground temp cooling revisited...

[greg273]

  I am once again looking into building a cooling system, based on the underground pipe setup.  I know some of you here have done this, specifically Gordy, if you are still around, how is your system working?

 At first, I considered the air based system, but issues of condesation have steered me towards the water filled pipe variant.  I am envisioning 1" buried water line, being pumped into a radiator with a fan behind it.  The concept appears sound, but I am having trouble finding the formulas for how much pipe is going to be neccessary to cool a well insulated 900sq.ft home...

 

[shagy]

cant help with formulas for how mutch pie but i can tell you that geo thermal heat and cooling is becoming the most comon sorce of heat in new construction hear in pa.

they say that a $20,000 heat system will pay back in energy savings in about 8 to 10 years, they being the company who makes the system.

     shagy

[Countryboy]

Hi Greg,

  You haven't provided enough information.  The square footage of the house is unimportant.  You need to look at the volume of the house.  (Do you have 7 foot ceilings, or 16 foot cathedral ceilings, or a cabin with a loft?)

  How much temperature change do you want?  How cool do you want your house?  Are you cooling a 100 degree house down to 65 degrees, or are you cooling an 85 degree house down to 75?

  How much heat is produced inside your house?  Do you have 3 deep freezes, 2 refrigerators, and tons of electric appliances?

  How deep are you planning on burying this pipe, and what is the average soil temperature at that depth?

  What type of water line do you intend to use?  A plastic line won't cool down the water as fast as a metal pipe will, but the metal pipe will corrode over time.

So how much pipe do you need?

Um, about that much.

[finnsawyer]

If you are talking about a heat pump, then be careful.  I've had experience with two different manufacturers.  The first was a dog, and was pushed by the power company.  I had the compressor go while it was still in warranty.  It went a second time for the guy that bought my house, out of warranty.  The one I have now seems to be very robust and reliable.  It seems that the compressors need a crankcase heater.  If that fails refrigerant will enter the crankcase and destroy the compressor.  Get one that shuts the unit down if the heater fails.

[Tritium]

Always try to request a Scroll Type compressor when you buy a new system or condensing unit or even a compressor. They are immune to damage from liquid slugging.

Thurmond

[GaryGary]

Hi,

I don't know much about this, so take these comments with a grain of salt.

I did try to assemble all of the actual design and build information I could find on earth tube cooling, and I put it here:

http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm#Other

This stuff deals mostly with air tubes, but some of the data might still be helpful to you.

My tentative conclusions after looking through this material are in the last link in the section.

Some things to think about:

- The Hait book states that the ground temperature is nearly constant year round at an average depth of 20 ft.  Above that it varies some with season -- the closer to the ground the more it varies.  

He further says that this 20 ft down temperature is about equal to the year round average temperature of the air in the same location.  So, 1) the ground temp in FL is going to be considerably warmer than the ground temp in MT, and 2) you are going to need to go down a ways to find some worthwhile coolth.

- I think you are right to be concerned a humidity.  With the scheme you mention, you won't have to worry about condensation in the tubes, but you still may need dehumidification to make the air comfortable after running it through the radiator?

This is just my prejudice, but I wonder if you would not be better off putting the earth tube budget into other things that would tend to keep the house cool?  Some of the links above seem to indicate that peoples expectations for earth tube cooling are not usually met.  You have already taken a good step by keeping the square footage of the house down.  I'd think about good insulation, good windows, good overhangs to shade the windows, good passive solar design, white metal roof, ...  and, a really efficient and slightly undersized AC for when you really need it.

A good article on optimizing a house for hot/humid climates:

http://www.builditsolar.com/Projects/SolarHomes/crumearticle.htm

Again, just my 2 cents

Gary

[wooferhound]

Here are a Bunch of other ways to get cooling in the summer . . .

http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm

http://techref.massmind.org/techref/other/spac.htm

[greg273]

 

   Thanks for the comments/advice and links.   Countryboy, here is a little more detail on what i am trying to accomplish...

 The house, being  approx 900sq ft, with 8ft ceilings works out to 7200 cubic feet of space.  I was envisioning a ten degree temperature drop, at a minimum, to make this a worthwhile idea.  Daytime highs here in Illinois are in the mid to upper 90's quite often, with moderately high humidity.  I was also hoping the cooled air would drop some of its moisture onto the radiator, where I could collect it in a bucket or something.

 I just scrounged some 1" waterline, I am going to check the volume of water it holds.

 By the way, this is an off-grid situation, so even a small Air Conditioner is going to be too much of a power hog for my limited PV budget.

 

[offgirdonhydro]

I did look into using water to cool my home.  I came up with using 4 2000 gallon tanks that would need the top of them at 20' or below to be able to cool my home to 75*.  It's about 14400 or so square feet.

The big thing you need to look at is how deep you will need to go and how slow you will need to push the water through the line.  I have not been able to figure it out with out using at least 2 tanks.  The tanks would need to be in series so the water would mix in to cooler water in each tank.  This would also give you the needed mass to make it work right.  I have gotten the figures with out using the tanks but then it comes down to the resistance of the piping.

The plastic septic tank is what I looked into and using 2" polyethylene pipe between tanks and the house.

How deep is you water table?  

Can you find any info on ground temps around you?

[Gary D]

 Old F. had a link to several air or water tube systems. I did a search and found the links. The link to the amount of 4" pvc piping is at the bottom of the page (for water they say add 20%). I haven't tried this yet (budget won't allow). If nothing else, it's a good read.... Gary D.

http://mb-soft.com/solar/alternwa.htm

[framistan]

The picture is me installing the 10ft radiator pipe in the 20ft hole. If you live in WESTERN illinois, I thinkyou may be lucky. I hear the groundwater there is only  a couple feet deep! Your underground cooling might work real good there.  I live in st louis county. I hear our groundwater is about 30 feet deep.  I drilled down 20 feet with a TEE-HANDLED drill and installed a thinwalled plastic pipe. (watchout for overhead powerlines when lifting the drill!!) I put temperature probes at 10ft and 20ft depth.  All summer the 20ft depth stayed 58 to 60 degrees.  But at the 10ft depth, it got up to 65 degrees towards end of summer. I found temperature goes up about 2degrees for each foot closer to the surface you are.  So... dig at least 10ft deep for most of us.  I also suggest drilling at some ANGLE... not straight down.  The reason for this is because HEAT RISES in air and water. (mud is water plusdirt).  You dont want your heat rising up alongside your cooling pipe, right?  I have been thinking of building this type of system for more than 10 years.  It takes a lot of planning because when you start construction, you must put MONEY on the line PLUS your reputation!  My wife's new hobby is HORSELAUGHING me about this idea, but I know it will work!  She looked at my note here and said, "OH, you've found another NUTTYBAR have you."  "yes" i said. She said... "how long will this nuttyness continue?"  I said, "Untill I SUCCEED!"  Now i am designing the in-house radiator.  I found the best place for the WATERPUMP is at the top of the radiator. This allows an unsealed open-ended system that will not get pressurized when water heats up. Also it allows any waterbubbles to escape easily. and it allows a TINY waterpump to work.  I plan on using a SMALL 66 gallon per hour fivedollar pump that only uses 4 watts of electricity (Water is easy to CIRCULATE because we are not lifting water out of ground like in a WELL... it is just CIRCULATING). Another important tip is to be sure to send your heated water to the TOP of the underground radiator!  Colder water will come out the BOTTOM, because HOT WATER RISES!. I have done YEARS of thinking, experimenting, and information hunting for this project.  I have solved MANY of the problems and am 75 percent done building a prototype system.   Anyone out there who is thinking HEATPUMPS you just don't understand!  The system i am trying to build would have no freon, no compressor, no complex systems, and require almost no electricity!  I wrote a 10 page outline of the system (too much info to type here) and will send to you or anyone who pays for my postage. Hopefully others can add to my knowledge and we will get a WORKING SYSTEM eventually.  my email is framistan@sbcglobal.net

[framistan]

UPDATE from FRAMISTAN.... In my earlier reply, i said if

anyone wants further info on my underground cooling idea

to email me and send a couple bucks for postage.  CANCEL

THAT because i later realized I could UPLOAD all the info

for EVERYONE for FREE just by using the DIARY section

of this website.  so check it out, and sorry I didn't

think of it earlier. Im a new user.

[freeEnergy4me]

I'm anxious to see it work.  I was thinking of just getting a 100ft sump pump hose, putting it in my basement and adding a PC fan to it, then just sucking the air out of my cool basement.

I really need to insulate my home though. A lot of the heating and cooling projects are worthless if your walls and windows defeat your efforts!