Quote:
Originally Posted by mrd
I consider the main distinction being that a fluid, typically water, is used to transfer the heat to and from the system. A typical 'split system' uses refrigerant. Hence all the benefits I described above.
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OK, I get it... I would describe it as an air source heat pump with a refrigerant-to-water heat exchanger located in the outdoor unit.
Yeah, this is just what Acuario has built.
There is a Japanese/European designed unit that is paralyzingly expensive that fits this description called the
Daikin Altherma (monobloc configuration).
I even went to a product introduction seminar and learned all about it. They have done their homework on these units. But when the entry-level price is about $18,000, only the wealthy can afford to save money.
Quote:
Originally Posted by mrd
From the perspective of a hacker or DIY-er, it doesn't much matter as one can build any kind of system they please...
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Yeah, hacking/DIY is what this forum is all about, and that is why I am here.
In fact, I have come to realize that when I think and speak about various heat pump and air conditioning machines, I tend to think in structural terms rather than in product terms or commercial terms, since it better assists me in understanding so that I can rip apart and re-structure these assemblies to suit my purposes.
Product loyalty bad, re-purposing good!
I am very intrigued by the possibility of getting an inverter mini-split outdoor unit and hacking it so that it goes refrigerant-to-water. This would allow you to use it in a radiant floor configuration. There has been a lot of development in mini-splits and their efficiency is very high now... getting close to GSHP standards. The inverter technology seems to be key. It would be ever so useful if someone could 'break the code' on inverter technology to the point that an ordinary hacker could re-purpose one of these babies for use in low-temperature hydronic heating.
This would be a very favorable combination of technologies, as low-temperature hydronic heating would lower the 'temperature lift' requirements on an already very efficient heat pump and increase its efficiency even further. ASHPs lose efficiency as they heat higher. R-22 units had a tough time getting above 120F, R-410a goes a bit higher... but the lower you go in required temp, the higher the efficiency, and a few degrees lower in temperature, means a large increase in efficiency over time.
In fact, it was in anticipation of and to accommodate such a development that I started the "Air Source Heat Pump (ASHP) Hacks & Mods" thread. This was before Acuario posted his work... so, because of his posts we are part way there, but we have a way to go yet.
I recently acquired (yesterday) a 2 Ton ASHP, not a mini-split like I would like to work with, but a COP 2 R-22 York, for $75. It has never been put into use, still has the un-brazed refrigerant fittings, and is reputed to have a full charge of refrigerant inside.
My thinking is to run the refrigerant lines just inside the house and make the refrigerant-to-water exchange happen there. This would keep the water part of the circuit safe from freezing, and easily get me into hydronic heating.
So, do I have a reverse cycle chiller? I don't know, but I certainly have a hell of a project on my hands!
-AC_Hacker