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paramax55 · 10-19-15, 08:32 AM

I have seen more and more posts with the idea of using mini splits. They are probably not the best choice for a DIY ground source heat pump. They are incredibly efficient and the off-brand ones are a fraction of the brand-name units. Yet they are not found all over the place and I figured there had to be a reason why. I asked a commercial AC guy (big company - high dollar) and my suspicions were confirmed. He said that they are noisy (I already knew that). While they can be reliable and last a long time, they can be troublesome when you first install them. When they break, there is also a shortage of people who can troubleshoot them and fix them. They are computer controlled and usually you have to find the bad board and replace the whole thing.

As far as hacking goes, it's all three phase motors. What you would need to do is rip out all of the electronics and install your own three phase motor controllers - similar to the idea of hopping up a modern sports car with twin turbos or something and controlling your engine with a "stand alone" engine management system.

The computer has algorythms to figure out how hard it needs to work to maintain a temperature in a room and then only runs at that level. It can balance the compressor for cooling (or heat) level, then balance the condenser fan for subcooling and evaporator fan for superheat. You would need to control these three variables for the level of heat transfer that you want.

This could be done if someone wanted to do it - anything is possible - but it's probably not good to jump in to that on the first try. There is so much more to a GSHP project that it probably makes sense to learn to crawl before learning to run. A hacked-up AC can be done so easily and cheaply that you wouldn't loose anything if you later switched to a mini-split and threw your initial project away after a year. But you would never do that.

The GSHP will be so much more efficient than other forms of heat transfer, you'll probably see no reason to go through the trouble of hacking a mini-split.

10-19-15, 08:32 AM	#1768
paramax55 Lurking Renovator Join Date: Sep 2015 Location: Florida Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	I have seen more and more posts with the idea of using mini splits. They are probably not the best choice for a DIY ground source heat pump. They are incredibly efficient and the off-brand ones are a fraction of the brand-name units. Yet they are not found all over the place and I figured there had to be a reason why. I asked a commercial AC guy (big company - high dollar) and my suspicions were confirmed. He said that they are noisy (I already knew that). While they can be reliable and last a long time, they can be troublesome when you first install them. When they break, there is also a shortage of people who can troubleshoot them and fix them. They are computer controlled and usually you have to find the bad board and replace the whole thing. As far as hacking goes, it's all three phase motors. What you would need to do is rip out all of the electronics and install your own three phase motor controllers - similar to the idea of hopping up a modern sports car with twin turbos or something and controlling your engine with a "stand alone" engine management system. The computer has algorythms to figure out how hard it needs to work to maintain a temperature in a room and then only runs at that level. It can balance the compressor for cooling (or heat) level, then balance the condenser fan for subcooling and evaporator fan for superheat. You would need to control these three variables for the level of heat transfer that you want. This could be done if someone wanted to do it - anything is possible - but it's probably not good to jump in to that on the first try. There is so much more to a GSHP project that it probably makes sense to learn to crawl before learning to run. A hacked-up AC can be done so easily and cheaply that you wouldn't loose anything if you later switched to a mini-split and threw your initial project away after a year. But you would never do that. The GSHP will be so much more efficient than other forms of heat transfer, you'll probably see no reason to go through the trouble of hacking a mini-split.