LO3
Honorable
- Sep 19, 2013
- 4
- 0
- 10,510
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Your buried copper idea I had also been seriously considering myself, but in South Carolina I would have had to go down 10' to get a constant temperature to rely on, and I had invested too much work getting grass to grow in my back yard to dig a hole to accomplish it.
Plus my wife already thinks I'm nuts anyway!
I could just imagine me telling her I was going to dig down 10' in the back yard to lay copper tubing in the ground to cool my computer? :lol:[/quotemsg]
I understand your wife's concern! Fortunately mine is an engineer, we both work in the energy efficiency industry so she not only understands the mechanical 'beauty' of some of the things I build but also sees the practical benefits they can provide to the environment and economy.
I wish I could find the pictures of the subterranean heat sink I built but they seem to have vanished so I'll have to give a try at explaining the design so you don't think you need to dig up your backyard. I used a roto hammer to remove a section of the basement floor slightly larger than the opening of a 5 gallon bucket. Once this circular section of concrete was removed I then took a 5 gallon bucket with the end cut off, stuffed it into the hole and started excavating the dirt in the center of the bucket - the deeper I dug the deeper I pushed the bucket to make sure the dirt did not collapse into the hole and undercut my foundation.
I used this method to go down about 3.5 to 4' under the foundation using a shop vac to remove the sand and dirt as I went. Once the the depth was right I used a 4' piece of PVC pipe and the vacuum to drill the 4 probes at an outward angle to the bottom of the hole. These probes are important because they get deeper into the ground and give access to a much larger thermal mass. Inside of each of the probe holes I set a 5' long 3/4 diameter piece of copper pipe filled with water and capped. These 4 pipes protrude into the cavity about a foot, after they were set I poured concrete into the probe holes being sure to keep the copper pipe centered in the shaft. The PVC was pulled out afterward leaving the concrete and copper free to transfer heat to the earth without the insulating properties of the PVC.
Once the 4 probes were set I coiled the 100' of 1/2 copper tubing so it was about 2" from the inside edge of the bucket and made a second coil loop a foot in diameter that coils up from the bottom of the hole about 2 inches from the outer coil. I run hot water down the center of the loop and back up the outer coil to the top.
I wired the coils, which fit right over the 3/4 probe tubing in the center of the chamber, together at a few points to keep them from moving when the concrete was poured. The chamber was slowly filled with concrete, the bucket pulled out and leveled even with the floor. I brazed a couple quick connects to the 1/2" coil and filled it with distilled water
My thinking is the hotter water going down the center fills the concrete mass with energy, the cooler water coming up the outside loses heat more readily to the larger exterior surface. I thought I'd try reversing the flow at some point but it is just so cool there has never been a need. The 4 probes transfer more heat down their length because they are thermally tied to the larger mass and loop coil; they protrude into the center of the loop so the heat can move through the concrete and copper down their length... no need to dig a 6 or 10' hole to lay the loop at that depth.
I put the whole thing under the house because the foundation insulates the earth under it from the sun and keeps its temperature lower. This way I can go down vertically with the heat instead of digging deep trenches in the yard and running more water in the loop to dissipate the heat because the earth is being warmed by the solar heat gain from above. In essence the earth under the house has a much more stable thermal mass regardless of season because the house keeps it insulated. Another plus, the computer sits above the heat exchanger so there is far less head pressure to overcome as well as better pumping efficiencies.
If you ever decide to give it a try I'd suggest using PEX instead of copper for the loop, that would be sooo much cheaper. You would loose a little thermal efficiency but there is plenty of 'cool' under your house so I doubt you would even notice.
And... don't tell your wife!
LO3
Your buried copper idea I had also been seriously considering myself, but in South Carolina I would have had to go down 10' to get a constant temperature to rely on, and I had invested too much work getting grass to grow in my back yard to dig a hole to accomplish it.
Plus my wife already thinks I'm nuts anyway!
I could just imagine me telling her I was going to dig down 10' in the back yard to lay copper tubing in the ground to cool my computer? :lol:[/quotemsg]
I understand your wife's concern! Fortunately mine is an engineer, we both work in the energy efficiency industry so she not only understands the mechanical 'beauty' of some of the things I build but also sees the practical benefits they can provide to the environment and economy.
I wish I could find the pictures of the subterranean heat sink I built but they seem to have vanished so I'll have to give a try at explaining the design so you don't think you need to dig up your backyard. I used a roto hammer to remove a section of the basement floor slightly larger than the opening of a 5 gallon bucket. Once this circular section of concrete was removed I then took a 5 gallon bucket with the end cut off, stuffed it into the hole and started excavating the dirt in the center of the bucket - the deeper I dug the deeper I pushed the bucket to make sure the dirt did not collapse into the hole and undercut my foundation.
I used this method to go down about 3.5 to 4' under the foundation using a shop vac to remove the sand and dirt as I went. Once the the depth was right I used a 4' piece of PVC pipe and the vacuum to drill the 4 probes at an outward angle to the bottom of the hole. These probes are important because they get deeper into the ground and give access to a much larger thermal mass. Inside of each of the probe holes I set a 5' long 3/4 diameter piece of copper pipe filled with water and capped. These 4 pipes protrude into the cavity about a foot, after they were set I poured concrete into the probe holes being sure to keep the copper pipe centered in the shaft. The PVC was pulled out afterward leaving the concrete and copper free to transfer heat to the earth without the insulating properties of the PVC.
Once the 4 probes were set I coiled the 100' of 1/2 copper tubing so it was about 2" from the inside edge of the bucket and made a second coil loop a foot in diameter that coils up from the bottom of the hole about 2 inches from the outer coil. I run hot water down the center of the loop and back up the outer coil to the top.
I wired the coils, which fit right over the 3/4 probe tubing in the center of the chamber, together at a few points to keep them from moving when the concrete was poured. The chamber was slowly filled with concrete, the bucket pulled out and leveled even with the floor. I brazed a couple quick connects to the 1/2" coil and filled it with distilled water
My thinking is the hotter water going down the center fills the concrete mass with energy, the cooler water coming up the outside loses heat more readily to the larger exterior surface. I thought I'd try reversing the flow at some point but it is just so cool there has never been a need. The 4 probes transfer more heat down their length because they are thermally tied to the larger mass and loop coil; they protrude into the center of the loop so the heat can move through the concrete and copper down their length... no need to dig a 6 or 10' hole to lay the loop at that depth.
I put the whole thing under the house because the foundation insulates the earth under it from the sun and keeps its temperature lower. This way I can go down vertically with the heat instead of digging deep trenches in the yard and running more water in the loop to dissipate the heat because the earth is being warmed by the solar heat gain from above. In essence the earth under the house has a much more stable thermal mass regardless of season because the house keeps it insulated. Another plus, the computer sits above the heat exchanger so there is far less head pressure to overcome as well as better pumping efficiencies.
If you ever decide to give it a try I'd suggest using PEX instead of copper for the loop, that would be sooo much cheaper. You would loose a little thermal efficiency but there is plenty of 'cool' under your house so I doubt you would even notice.
And... don't tell your wife!
LO3
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