That geoheat.oit.edu paper is about 15 years old and GSHP installs are a lot more expensive these days..
The tech that I hired was working as a temp in the HVAC dept. at a local college facility.
He said when times are good, he runs his own AC repair company.
I got my unit from these guys..
24KHS72
No problems, but it takes a long time for units to get here from China..
When I ordered mine, I knew it was out-of-stock.
Their tech guy is always available to answer questions.
He has done a lot of mini-split installs and knows his stuff.
I didn't have any problem at all with Sanyo tech support, getting their paperwork going for the replacement unit.
The parts warranty was still good, it's just the labor they don't cover.
I think the defect was a very tiny pinhole in the copper tube where they
brazed on a short piece of tube to hold a heat sensor. (clip-on)
Not even a connection, just something to transfer the heat to the sensor.
I think it's likely that it was a little low on R410A when it was shipped, but since it ran so well, the problem wasn't noticeable.
But after 45(?) days, it just got to the bottom and the compressor cut-off kicked in..
From what I can tell by looking at the workmanship inside the outdoor unit,
the units are well designed and look like they should last for decades..
I'm hoping to get a perfect specimen this time.. I plan to run the heck out it this summer..
Cheers,
Rich