From what I have been able to gather, heat exchangers cost you about 10% in efficiency. I think this is one of the ideas behind HX systems... get rid of a HX and gain 10%.
I don't understand why no one is using DX floor heating, and cutting out that 10% loss also.
Seems to me that with copper tubing in the floor and all on the same level, the lubricant loss issue would not be so bad.
-AC_Hacker
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