The Peltier doesn't have a high enough dT to make it worth while. I would make the HP. I have a friend who made a whole house drainwater HP 25 years ago and it worked well for many years in his low energy home. Taking heat out of the 10C water works well too. Lots of energy there but unfortunately, you have to design a system to work with poo, haha (I'm not fond of that part)
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