Diy, Green, Home Improvements

Quite recently, AC Hacker finished digging all the bore holes necessary for his heat pump system. So, the next step in the digging process was to dig the trenches that will connect the bore holes to each other.

To do this job, AC Hacker decided to visit the local power tool rental shop. He ended up selecting the machine above because it looked somewhat more maneuverable than the other types he saw there. As he later found out, this was not the case.

Even though the trencher was very hard to move around, once it was in place, the hydraulic controls took over and the machine did its job well.

During the digging, great care was taken when the machine neared the tubing that was already in the ground.

With the trenches dug, AC Hacker comments on how he never wants to see a shovel again and happily moves on. The next step was to start connecting up the bore holes. This is currently still in progress, but he says half the field is done.

AC Hacker also mentioned he thought he would have to use barbed fittings in some places in the system. However, when he tested them he was not happy. He commented that welding is not only cheaper, but it is also easier, more durable, faster, and more likely to yield a leak free connection. So, he is welding where ever possible.

For more details about the tools and project check out AC Hacker’s forum thread that tracks all of his progress.

{ 0 comments }

Now that AC Hacker has his home made plastic welder all put together, he could start doing some welding.  But, how was he to know if his welds were all sealed perfectly tight?  They certainly need to be, otherwise the system will leak.  Well, another tool and some testing told him what he needed to know.

First off, he had to weld up all the loop ends that go at the bottom of the bore holes.  These pieces each consist of five total welds once in place.  Three of the welds are at the ends to form the loop.  Two more welds connect the loop ends to the rest of the tubing.

Here is the pressure tester that AC Hacker used to test his welds.  It consists of a barbed fitting to connect to the tubing, a pressure gauge to ensure that the tube is pressurized, a tire valve to fill the tubing up with air, and a plug for the other end of the tubing.  All he has to do is connect the the tubing up to the two barbed fittings, tighten the hose clamps, and pressurize it.

The pressure gauge alone would show leaks, but it would take some time to show up as the pressure slowly drops.  To speed up the testing process, AC Hacker decided to put the tubing into a bucket of water.  The escaping air bubbles would be quite visible.  The picture above shows a good solid weld.

As you can see, a leak is very visible once in the water.

All in all, with AC Hacker’s home made welder, he only found two bad welds in the 90 he had to make.  Not bad at all!  However, he emphasized that testing every single weld is absolutely necessary since one leak will kill the entire system.

For more details about the tools and project check out AC Hacker’s forum thread that tracks all of his progress.

{ 0 comments }

In part 4 of our series, AC Hacker had just found out he could weld plastic without too much trouble. He used a skillet on a stove, heated up two short pieces of tubing, and pushed them together forming what you see above. He noticed that the plastic started to melt right around 300°F (149°C). So, he figured he could think of some way to create an inexpensive and more portable tool to do the same thing.

Not being too sure of the quality of the weld, AC Hacker took the piece he had welded up to the local machinist. There, they tried to tear the pipe apart. What they found out was that it tore everywhere else but the weld. So, the weld was in fact strong enough.  After tossing ideas around with the machinist, AC Hacker decided to take the skillet to the band saw creating two rectangle pieces for his would be tool.

On his way home, AC Hacker stopped by the local Goodwill store to look for electric heating elements.  This is an idea the machininst had offered.  He found a nice small one in a mini-sandwhich maker.  This small set of heaters would prove perfect for his tool.

With the heaters in hand, AC Hacker made a return trip to the machinist.  Previously, the machinist had offered to mill slots in the skilletplates for the heater.  So, that is exactly what he did.

To add temperature control to the new tool, AC Hacker used an electric skillet temperature control.  This allows him to dial in whatever temperature he finds to work best for welding the plastic tubing.

The last step for the tool was to add some electrical insulation to prevent getting shocked while using it, and to adjust the temperature for the actual welding.  Once the temperature was set, AC Hacker taped up the temperature dial so it would not accidently get changed.

With the tool done, he needed a way to hold the pipes square to get a solid weld.  The above is the welding jig that he came up with.  After making it, he noted that such a nice setup is not absolutely needed and that one could easily make something out of wood that would work just as well.

With these new tools in hand, AC Hacker is setup to create the welds needed for the heat pump system.

For more details about the tools and project check out AC Hacker’s forum thread that tracks all of his progress.

{ 0 comments }

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.

{ 8 comments }