In this thread:
In western VA (below West Virginia) I can't find an HVAC/Mechanical contractor willing to take the leap and be first with A2W monobloc heat pumps. As a retired mechanical engineer with enough expertise to run PEX, install heat spreaders, baseboards, fan coils, etc., I'm a bit frustrated. This may have to be a modified DIY job with help from skilled friends IF I can get my hands on equipment and controls at a reasonable cost. (I have Manual J loads and a recent energy audit with blower door to address envelope issues and sizing for this 1965 leaky ranch house over basement.). Basically, contractors say "you want what??" and when they understand more say "we don't want to take the risk with what we don't already know. There isn't a lot of hydronic work/skill in this area anymore. Note: for several reasons, I don't want mini/multi-split systems.
Any suggestions on buying A2W HP equipment directly or through a third party and taking on the risk myself?
we talked a lot about how the output and COP of various heat pumps declines as the outside temperature drops. None of the air-to-water heat pumps do as good a job of retaining their capacity as state-of-the-art air-to-air units with vapor injection. The performance is determined entirely by the construction of the compressor, which got me thinking that wouldn't it be nice if you could somehow use one of those compressors to get heated water as your output. That got me thinking, imagine if you had a multi-head minisplit, and one of the heads had a water output.
That isn't by itself a crazy idea, that's exactly what the LG HydroSplit is, a head that goes on a multi-head system usually used for air-to-air. Of course the issue with the HydroSplit is that it doesn't seem to be actually available for sale.
So the crazy idea is, what if I built my own head? In heating mode, the heads for a heat pump are really simple: hot, pressurized refrigerant is run through a coil and heat is extracted. I've read about people doing it with just a coil of copper tubing. To produce hot water, you'd probably want to use a flat plate heat exchanger, with a circulator pump to move water through and take the heat away. You'd need some sort of controller, which would assess how much heat is needed, send a signal to the compressor to generate that much heat, and modulate the circulator to remove that much heat. I know a lot about programming microprocessors so the hardest part would probably be figuring out how to communicate with the compressor.
Thoughts?
