DIY Ground Source Heat Pump – Part 6: Testing Plastic Welds

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.