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Old 12-14-12, 02:36 PM   #244
Piwoslaw
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Quote:
Originally Posted by Student 07 View Post
I have some concerns about combining the HRV with a HP (which would be a hacked dehumidifier or AC unit): most HRV are rated at 150-350CFM while an Air Source Heat pump requires a lot of air. My 4 1/2 ton unit flows about 3500CFM.
This is a small heat pump, it doesn't need a 16kW compressor! Since you'll have relatively slow airflow, then make the HP's heat exchangers large. Also, you won't be moving a terribly large amount of heat, plus the temperature difference is small, so you could probably get away with a compressor from a fridge or freezer. OK, not a 30W tiny fridge compressor, but a 150-250W compressor from a larger unit might suffice.

Going slightly off topic, in that drawing of mine I suggested that the intake path start with an underground heat exchanger to preheat the fresh incoming air, which should also lower the temperature differential between the two airstreams coming out of the recuperator.
Since building an underground HX isn't always possible, how about a solar collector instead? Imagine that the recuperator's fresh air enters through a vent in the wall. Now place a solar box in front of the vent (south facing insulated box with glass on top). If the sun is shining, then the intake air gets free heat, else it is the same as without the solar box. Similar to a solar air warmer for ASHP I once proposed.
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