(* Thankfully we can get pack to the purpose of this thread *)
Quote:
Originally Posted by jeff5may
Ok, so to answer DonT's questions directly:
1. A 11KBtu compressor feeding a hydronic HX would probably not heat his barn-home during frigid weather, even at 130 degF supply water temperatures.
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I agree with you jeff5may.
I looked up the degree days for January, and his chart looks like this:
Clearly, his big heat requirement was during Jan 16, 17, 18.
I used his numbers, and calculated his BTU/hr output for Jan 17 (worst day). It came out to 18113 BTU/hr.
And the compressor he has can deliver an ideal maximum of 11,000 BTU/hr.
His compressor would also be subject to HX losses, etc.
Quote:
Originally Posted by jeff5may
2. A GSHP would probably not be highly efficient running against a 175 degF water-heater-turned-boiler. It may save some electricity in the long run, but would have a relatively short lifespan.
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Efficiency is the ratio of energy out divided by energy in. So the compressor would almost certainly be more efficient. But the one he has will not able to produce the amount of heat he needs. The red line in the diagram is what his compressor could deliver. I suppose his compressor could be used to supplement his other heat sources.
But then there is that darn delta-T issue. His BTUs will be at a lower temperature as you said.
Quote:
Originally Posted by jeff5may
3. The staple-up (or similar) hydronic heating loop would be much less efficient running at 130 degF than 175 degF, and would seriously reduce heating capacity of the system as a whole. MMT and BBP have discussed this at length in the DIY hydronic heating thread.
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Yes, terribly inefficient. All radiant structures for heat pumps need to be way more efficient that those used for fossil fuel, if you want to gain the full benefit of GSHP.
-AC