My geothermal cooling loop seems to work

[NateHanson]

Not if they two legs of the U were separated by enough soil. I have no idea what "enough" is though.


Matt, why do you think a deep well would be better than 4 feet underground? Won't the temperature essentially remain at 54 degrees regardless of whether you're 4 feet or 400 feet underground?

 

[Matt L.]

Not if they two legs of the U were separated by enough soil. I have no idea what "enough" is though.

Neither do I

Matt, why do you think a deep well would be better than 4 feet underground? Won't the temperature essentially remain at 54 degrees regardless of whether you're 4 feet or 400 feet underground?

Because of the energy you could save on pumping.

You could power a very large cooling well with a very small pump; there's no change in static head and no real head loss.

If I want 1200gph through such a well, then there's really no reason why I couldn't use a MJ1200, even if the well were very large!

Matt

 

[Greg Hiller]

>Because of the energy you could save on pumping<

If the tubing is all filled with water it shouldn't make any difference whether it runs horizontal, or vertical. Drigging a trench is a lot easier than digging to China. I was thinking the reason you wanted to dig deep was that the ground would be wetter and therefore the heat exchange through the soil would be better.

 

[Matt L.]

I was thinking the reason you wanted to dig deep was that the ground would be wetter and therefore the heat exchange through the soil would be better.

That too. I still think the best efficiency is to be had with saturated soil well below the frost line.

Matt

 

[reefsmurf]

Is there any way to plumb a line through the freezer of your fridge?

 

[Scuba_Dave]

Is there any way to plumb a line through the freezer of your fridge?

Sure, just avoid the freon lines.
They areally aren't made to run for extended periods
People have tried this with mini-fridges

They are made to chill or freeze items, then maintain that temp
They aren't made to work on an ongoing basis

 

[marco67]

Well I sunk my 6 loops yesterday;
I ended up using the 1/2" Toro blue stripe tube ...it's a plastic/ poly tubing with a very thin wall.
Each loop is 100' and 7' below grade. I laid a sheet of poly down first to help keep the soil (sand) moist longer and used stakes to help keep all the tubing seperate. In order to further seperate the loops we laid 3 loops then back filled ~1 foot then did the next 3.
The thing that sucks is now it will be at least 2-3 months before I can try it.

 

[~Flighty~]

Toro blue stripe is the black stuff for watering systems? I use that to run wast water out to the garden. I may have to try dropping a few 100 feet of it into our shallow well and seeing what it does.

 

[marco67]

Yea that's the stuff ....I went with it because of the super thin wall, "should" = good heat transfer. the down side is how easily it kinks you have to be very careful working with it I had to use 2 stakes for every turn and wide radius...but once buried and back filled it should be all set.

If your going to drop it into the well you will need to use some type of strain relief, it will not support it's own weight (maybe like put the whole coil in a laundry basket and lower it with nylon rope?)

 

[~Flighty~]

Did you test a coil of it in a cold water bath before you burried it?

Hmmmm, If I can figure out something to use as a pump I could do that now...

Edit for thinking outloud: I wonder if anyone is taking advantage of the cold water from their well that is used to make rodi. I could potentially kill two birds with one stone and have both cooling liquid for the tank and warmer input water for the rodi...

 

[marco67]

Did you test a coil of it in a cold water bath before you burried it?

No why ? what are you thinking?

 

[~Flighty~]

just wondering how fast it would cool the water in the loop and how much it would cool it at different flow rates and line length.

 

[marco67]

Ahhh, nope no testing
I loosely based the size and length on calculations here and in an RC thread http://reefcentral.com/forums/showthread.php?s=&threadid=817756&perpage=25&pagenumber=1
In the end I'm just a down and dirty type, you can draw pictures and bang on a calculator all day but in the end you just never know until you go for it.
so that's what I did ..I tried to choose a size and material that would give me the most options moving forward then ...got dirty!
once I find out what type of pull down I need I'll play with pump sizing etc ...If I have to I have the option open to twin the 100s in parallel or series also.

 

[Scuba_Dave]

Why 2-3 months to test? It's going to be in the 80's next week
Or are you still setting up the system it will be connected to?

 

[Greg Hiller]

>In the end I'm just a down and dirty type, you can draw pictures and bang on a calculator all day but in the end you just never know until you go for it.<

Yup! IMO, the biggest problem with all the calculations is knowing how well the heat can move away from the area of the ground you heat, and that in the end really takes some experiments.

>I wonder if anyone is taking advantage of the cold water from their well that is used to make rodi.<

Yup! Actually I was thinking about this again today. I had originally planned running a line of the water through my sump Before it went into the RO/DI system, but that would mean it would be under high pressure, and if it needed to be a long length of line I'd be nervous about a fitting leaking and putting tap water into my tank. Then I realized I'll get almost the same cooling effect with the water on the way out of the RO/DI system, I'll just need to run both the 'clean' and 'dirty' water though the sump. This way it will not be under much pressure.

To give you an idea how much cooling effect this will give you:

I have a 50 GPD RO/DI system, which probably uses about 200 GPD total while running. If you assume water (this time of the year anyhow) is coming in at 55 F (I don't know if that's accurate), and is warming to 78 before it leaves a loop of tubing in your sump, then you are removing about 1600 BTU/hr from your system, which is equivalent to a small chiller, and a little more than the calculations on my loop suggest I'm removing with my loop.

 

[marco67]

Why 2-3 months to test? It's going to be in the 80's next week
Or are you still setting up the system it will be connected to?

Um well ....I still have not built the building that I will set up the systems in that it will be connected to.

 

[Scuba_Dave]

I like the RO/DI idea
Sounds like win - win - warm the water up for the RO/DI unit & cool the tank some

Still waiting to have my foundation put in. I need to finalize a plan - or multiple plans before then

 

[Yaktop]

to do it all over again greg, what would you do different?

 

[Greg Hiller]

Ed,

>to do it all over again greg, what would you do different?<

Good question. I checked my loop again last night. There is still a 2 F temp difference between the water coming out of the ground, and that going in. So....if I were to do it again, I'd probably use 12 to maybe 16 of these aluminum tubes (instead of 4), all plumbed in parallel. All spread out over as large a surface area as I could, as deep as possible (within reason). Of course, only time will tell whether the tubes will last in the ground.

Marc's method might also be a very good one as long as the tubing does not spring a leak anywhere.

 

[Yaktop]

wondering how long those thin aluminum tubes will last. I guess depends on how acidic your ground is I guess. If those tubes did last a decent length of time I would use them. So in your sump you use plastic tubing or something else? sounds like my next project once I get comfortable on which types of exchanges to use both in the ground and in the sump. my chiller is running as we speak