Geothermal loop

[grouper therapy]

Im late to the party here. but a pump to push through 200lf of pipe, plus the 1hp heat exchanger. youve replaced the radiator and fan found in most chillers, but is that saving money? Im not so sure...

might have made the exchanger more efficient giving it a better heatsink than an ambient temp radiator of 73 inside and 90+ outside. not sure how much efficiency this is adding vs the cost to run the water pump? I guess some, but it would still be far from free.

f

 

[grouper therapy]

ares;492159 wrote: Im late to the party here. but a pump to push through 200lf of pipe, plus the 1hp heat exchanger. youve replaced the radiator and fan found in most chillers, but is that saving money? Im not so sure...

might have made the exchanger more efficient giving it a better heatsink than an ambient temp radiator of 73 inside and 90+ outside. not sure how much efficiency this is adding vs the cost to run the water pump? I guess some, but it would still be far from free.

free (or as close to it as it gets) would be to pump straight salty tank water through the ground loop with no powered exchanger. but that would not be as effective, trying to cool 80 degree water to 55 degree earth, and no heating ability without the exchanger.

Not sure what you are talking about but the pump that runs the closed loop draws 5o watts max so that equates to $5.58 per month if it ran 24 hours a day . It only ran 8 hrs a day last summer which would cost $1.86. The tank water supply is in the return loop so there is no additional cost there either since it did not require an additional pump. Running the tank water through the loop would be a more efficient means of heat transfer but then you have the issue of stagnant water creating hydrogen sulfide in the loop when it is not running plus a better chance of contamination. I prefer to take my chance at the titanium heat exchanger. The 1hp chiller had a locked compressor so it was basically free . After the initial cost it cost the $1.86 to run the pump and whatever the digital temp controller burns. I am guessing $1.00 a year. So not it is not free but I burned more watts posting this than i did cooling my tank today with 1500
+ watts of light on it.

 

[grouper therapy]

Skriz;491994 wrote: It's starting to get warm..any updates?

So far it has maintained the tank at 80 which is the same as it did last summer. I still will add 200 lf of pipe to the loop this spring summer sometime. I would like to pull it down a couple more degrees.

 

[enderg60]

He took a 1hp chiller that did not work and cut out the titanium coil(heat exchanger) and used that for the ground loop and trashed the rest of the chiller.

Now rather then being cooled by freon(and a big compressor that tanks crap loads of power to run), it uses cold water from the ground loop.

 

[eric b]

Dave,
Let me know when you are ready to install the rest of the loop. I had offered to help and it is still on just need to know when...

 

[fetch]

So, you didn't run into any issues with using PVC pipe in the ground to transfer heat? PVC is a good thermal insulator, compared to copper or iron.

 

[grouper therapy]

Fetch;496549 wrote: So, you didn't run into any issues with using PVC pipe in the ground to transfer heat? PVC is a good thermal insulator, compared to copper or iron.

I used thin wall PVC which is like schedule 20 I believe .You are correct about it's heat transfer properties versus copper. But the difference in it is not enough to justify the price difference. I could purchase 10x the thin wall pvc pipe for the price of the copper. I think it is a poly type tubing that is used in the vertical geo loops that are installed for HVAC units now. From my research the pvc would efficiently transfer the max heat in the loop since only a certain amount will transfer in any pipe.

 

[weaglereefer]

Would the schedule 20 be more prone to cracking? And is there a "plan" of any sort to replace if/when pipe does start cracking?

 

[grouper therapy]

I'm not sure why it would crack but yea the thinner it is itwould be easier crushed . I can't figure how it would be crushed 5 feet under ground in my backyard but I guess anything is possible.I'll let the next generation worry about the replacement and if it doesn't last I can rent the mini excavator for a day$200 and 40 bucks worth of pipe and replace it. There is no pressure on the system since it is a closed loop so that should not be an issue either.

 

[fetch]

a PVC pipe buried underground will last 50 years, easy.

 

[enderg60]

yup if you do a geothermal loop for your house, it will be run with a flexible PVC type pipe. Copper would only be a good idea if you were doing a burried concrete heat sink.

 

[morganatlanta]

Grouper-
Any update on this now that you've been through a summer? Did you ever add the extra 200 ft? I'm seriously considering something similar.

 

[grouper therapy]

MorganAtlanta;578070 wrote: Grouper-
Any update on this now that you've been through a summer? Did you ever add the extra 200 ft? I'm seriously considering something similar.

never did add the extra 200 lf. The temp maintained 80 all summer.

 

[toph]

Great idea...I like these sort of projects.

 

[eagle9252]

any updates? and you still using it?

 

[rdnelson]

Didn't have the time to dedicate to read the whole thread but here is what I learned in the early 80s from Mother Earth News. Planned on using it on a house I wanted to build in AZ.

To get the constant temp, you need to be at least 6'down. I agree a heat exchanger is the way to go. If you put a glycol mix (basically anit-freeze) you get a better heat heat transfer. Metal pipe would be much more efficient but as you mention, cost would be prohibative. Last, circulate the loop water slowly to allow for more heat transfer.

 

[eagle9252]

About 6 yrs ago I had planned to do a loop off the water heater for a slab but still have never poured it yet.

But for the most part tank is 77.4* now but in the afternoon it will go up some or depending on if the window units are on or not it's been @ 81*. About a week ago I made a simple heat exchanger that loops SW from the sump through ¼’ tube in front of a fan and back into the sump.

I have 2 fans on the sump and 1 on the canopy that are on 24/7 and I still have the 2 that are on a thermostat when the LEDs are on. They don’t come on when the lights first come on but do later and never turn off until the lights turn off. LQQKs like I need to up the size of those fans.

 

[grouper therapy]

i still have it installed but do not use it as my big tank has been taken down. I may need it on the cube not sure yet. Metal pipe doesn't make much of a difference since you are limited on the heat transfer anyway.Actually water transfersr the heat quicker than glycol, it just rust and will freeze quicker. So far as depth that can very from region to region and the actual location such as shade etc. I am at 5 feet with mine.