DIY Geothermal Ductless Mini Split (Ground Source Heat Pump)

This is a DIY video demonstrating how I modified an air source ductless mini-split to be a ground source heat pump (geothermal) mini-split.

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Heating Degree Days

[TNorin]

Heating our 70, 000 gal pool is very expensive. If I could also add cooling to the house- win/win. This is mainly a Summer thing, but could get some thru the Winter.

[hexadcml]

I hadn't thought of the excellent framing of COP as fraction from electric/fraction from source/sink.

[nickflynn]

Great that you managed to calculate the COP and prove that its a workable system even with less than ideal heat exchanger. One thought is that you'd save electricity overall by heating thoughout the day and have smaller setback temperature at night. Naturally it depends on the heatloss of your house and how much insulation you have. I'm in the UK and we are taught that you should always leave heatpumps on as much as possible with a small setback temperature at night for comfort if necessary because the cop gain will save more electricity overall despite the higher housing heatloss. This is unlike gas boilers where people often use 'stop-go' heating to save money. But we mostly use air to water heatpumps here so maybe that wouldn't apply to your setup. Such a heating schedule might also fix your reverse flow noise issue as the heatexchanger won't get so cold if it's working less hard over a longer period?

[paulboucher]

Really nice project

If you do not want your pump to run on reverse you could make something out of a bicycle rear gearset, they only run in one direction...

Im in the process of modyfing a mini split I got off marketplace for 100$, I want to heat my domestic hot water.

First test results show a cop of 3.12

[ug]

i ´m always thinkink about a sandbattery powered by 12v solar to heat up the air sucked in ...

[theinfernalcraftsman]

Nicely done. I looked at doing a GSHP years ago but it doesn't work well where I am. Soil issues and it's just not cold enough without going very deep and I'm in a cooling dominated area. My 100' irrigation well water temp is 70*. Drilled wells are the only effective method here and it's cost prohibitive. I did allot of research back then and I find that now allot of the information I used to be able to find easily is very hard to find now. In the end they can be done where I am but only worth the cost if you have a large pond or live on a lake and can do a water loop. Our summer temps are at or above 100* from around 11am until 6pm and the low is 80* and it will still be in the mid 90s at midnight. (TX)

For your fan motor it may be going into reverse during a timed defrost when it hasn't done one in a long time and overrides the temp sensor data. But to fix the issue you could look at adding a sprag clutch so the pump will freewheel when it goes into reverse.

I hope you get more views but sadly in depth tech info doesn't do well on YT. Neither does detailed instruction on stuff. People want simple and fast but mostly entertaining. Not many want to learn anymore.

Oh and forgot... The issue with the pipe you wanted for the ground loops... Well as of last year it's illegal in most states. Sadly there is no replacement product for irrigation use at a similar price anyway so you have to go to a state that sells it and smuggle it in across the border. In fact Menards has it on their site that they won't ship to those states now.

[tvpi-zv]

Any chance you could show us a graph of total system power Watts for one day.

[georgetaylor]

What is your address? Not obvious where you are - or did I miss that?
You have a lot of land … and making all those deep trenches would destroy a garden. I guess you have a lot of grass.
Writing from the UK