by Tim Fulton on September 8, 2009
With a capable drilling rig, AC Hacker turned to selecting parts for the rest of the system. Specifically, we’ll be looking at selecting the tubing that must be laid in the ground.
PVC and CPVC are not a good choice. They both get brittle eventually and will crack under pressure. Pex would be a good material. However, with the way it is made, it is not possible to weld it together. Copper would also work well, but it is very expensive.
So, that left AC Hacker with what he had read about many small residential systems using, HDPE (high density polyethylene). Its that black water tubing you’ve probably seen at the home improvement store. AC Hacker found that HDPE comes in two schedule ratings, 40 and 60. The 40 was too thin to think about using as he feared it might be crushed by the weight of the soil on it. But, the schedule 60 looked like it would be up to the job.
The next hurdle is that HDPE needs to be welded together. AC Hacker looked into what kind of tools would be needed for this. He found McElroy makes a tool called the MiniMc that is made specifically for welding plastic pipe. The bad thing is it costs $2000. He also found that even renting it was very expensive.
Since that would blow the budget for this project out of the water, AC Hacker decided to look into how hard it is to weld the tube without this tool. He picked up a teflon skillet from the local junk store and heated it up on his stove at home. He placed a couple short pieces of HDPE on the skillet and monitored the skillet’s temperature with an IR thermometer. At about 300°F (149°C) he noticed a bead forming around the tube. He picked two pieces up and pushed them together. The above was his first result. So, plastic welding is indeed possible without the very expensive tool.
For more details about the tools or project check out AC Hacker’s forum thread that tracks all of his progress.
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by Tim Fulton on September 1, 2009
To make his life a bit easier, AC Hacker decided to build an electric drilling rig. He did dig a few holes with the manual drilling rig and it worked fine. However, he calculated that he needed around 200 feet of borehole and decided to make something better.
The frame of the drilling rig is made mostly out of square tubing with some plate here and there.
The head for the drilling rig consists of another close fitting square tube that slides over the frame tube. This allows the head to be moved up and down with the red wench you can see in the last picture. Attached to the head is a 1/4 horsepower 25:1 gear motor.
Attached to the gear motor is a home made flexible coupling. This dampens shock loads and allows for some misalignment in the system. The coupling is made from two flanges, a rubber disk, some bolts with nyloc nuts, and rubber and regular washers. This coupling has gone through a few design changes and this is the one AC Hacker has settled on (for now at least).
The last piece we have here is a fancy water connection. The drill shaft must rotate, but you don’t want your water hose to rotate with it. So, AC Hacker constructed this swivel adapter. It is made from a PVC compression T, two sealed bearings and a piece of pipe. Construction details of the swivel can be found here.
In addition to the drilling rig, AC Hacker made a few other hand made tools. The pointed tool works well for chipping through clay and the bladed tool works well for cutting through roots. He also made the shop vacuum extensions shown above that works well for removing dirt and even rocks from the holes. These tools have allowed him to drill 11 of the 16 holes that are necessary for his heat pump system.
For more details about the tools or project check out AC Hacker’s forum thread that tracks all of his progress.
by Tim Fulton on August 26, 2009
In our first article, we gave a very brief overview of AC Hacker’s heat pump system and the testing he had done. Now, we will dive deeper into the process he is taking to make up the system.
For the heat pump system, AC Hacker decided to go with a water to water design. This worked best for him because it requires less length of tube to be put into the ground. More tubing in the ground obviously increases cost, and even putting tubing in the ground is a major problem for DIY heat pump projects.
In order to get the tubing into the ground, boreholes need to be drilled. The average person doesn’t have any well drilling equipment handy so something must be made. The first version of AC Hacker’s drilling rig is show above. It is comprised mostly of pipe and a few fittings.
The top of the drill is a 4 way fitting with three pipes connected to it. Two of the pipes are for handles to turn it. The long pipe goes to the drilling tip, and the top goes to a swivel fitting that connects up to a garden hose.
The business end of the drill is just the end of a pipe with some steel plate welded to it. The water from the garden hose blasts out the tip of the pipe and flushes out the debris from drilling, assists with drilling, and also stops the hole from caving in when drilling through sandy soil.
With this drilling rig, AC Hacker was able to drill down 13 feet in about 35 minutes. Not bad for a hand tool. However, at 13 feet, he started hitting hardpan. Hardpan is clay mixed with gravel. This is not fun or easy to drill through. However, it also keeps the water level up which can increase the efficiency of heat pump systems.
In our next article, we’ll talk about AC Hacker’s improved electric drilling rig he made. If you don’t want to wait, check out his forum thread.
by Tim Fulton on August 18, 2009
For a while now, one of our forum members, AC Hacker has been working on a DIY solution for a ground source heat pump, or what he likes to call his Homemade Heat Pump Manifesto. Yes, a DIY solution for those incredibly efficient and incredibly pricey heating and cooling systems. He has been making some great progress, so I thought it would be a good thing to share with our blog readers that don’t always make it over to the forums.
AC Hacker started out making the smaller prototype unit (pictured above) to see if it was all possible. This small unit actually turned out to be pretty efficient. The initial calculations showed the prototype running over 400%. Heat pumps are capable of exceeding 100% efficiency since you aren’t creating heat, you are simply moving it from one place to another.
With the prototype being a success, he started planning for a full size system for his house. He believes he can put an entire system together for under $2000! Commercially installed systems start at $15,000 and go up from there.
There is a lot to this project, and we’ll be covering it as progress is made. If you really want to jump into it you can check out AC Hacker’s forum thread here.
