Quote:
Originally Posted by jeff5may
Old school ODU from post # 27 is back, this time only $90!
Heat Pump
For $90, this unit is worth it even if the compressor is bad. Needs at least an indoor unit. |
Indeed! This would be a really good starting point.
On this vintage (pre-minisplit), they didn't really have an "indoor unit".
Rather, they have an air handler that is inserted into the forced air system, and a properly sized set of evaporator coils is inside the air handler. Then a thermostat completes the setup.
It wouldn't be a huge challenge to substitute a large brazed plate HX for the evaporator coils in a forced air system (TXV instead of cap tubes), and use such a rig to heat a concrete slab (rigorously insulated on the underside, of course).
Quiet, efficient, thrifty (they're essentially giving it away), readily obtainable parts...
I wouldn't be surprised if that unit still had a full charge of R22 already inside of it.
With a properly built slab, the temperature of the water-in could be pretty low (still gotta consider the overall heat load, of course).
I messed about with the Carnot efficiency theorem, and when you are able to lower the feed temp to the slab a little, the efficiency of the heat pump goes up a lot.
-AC