Jeff, I don't believe the fan or the sensors are too much trouble. The temperature variation here as air vs water is not much in mild winters ( actually in mild winters Danube is a little bit colder than the air sometimes). I'm planning to use the actual fan controls to power up a brushless dc water pump, from my initial investigation, voltage and rpm wise it seems to match, although I would rather have a faster pump to avoid freezing up the hx.
The trick is to control hx freezing or even to use the current controls to heat up a very cold HX, and again I don't think this is too tricky, maybe I'm ignorant. What I can be sure is that the unit will think the hx is frozen more often in an WSHP config, but I have seen people tweaking the temp sensor for allowing colder temps in the hx without going into defrost mode. It seems the unit does defrost in 2 ways, first it reverses flow of refrig., secondly there is a heat strip in the pan to clear ice from the pan. I can use the heat strip strapped to a hx to heat it up. Also - defrost only seems to happen when frost reaches the top sensors on the hx - you can see it in the photo. Tweaking the defrost seems doable to me.
Question: does anyone see a problem with using a very large suction line HX as the actual outdoor water to refrig. HX? The problem I see is refrigerant flow minimum speed to be reached to carry oil back. Anything else ?
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