{"items": [{"author": "Bob", "source_link": "https://www.facebook.com/jefftk/posts/10100132902244672?comment_id=10100132905782582", "anchor": "fb-10100132905782582", "service": "fb", "text": "this kind of problem is interesting because it has several degrees of freedom and results of experimentation are often independent of what one expects in reasoning from first principles. i have a system with a gas furnace and outdoor heatpump/ac, and the crossover point was set to 25f, ie, above 25 the heatpump would function. i found in winter that the heatpump was ineffective below 40 (the system would blow cold air), and in a recent service call learned that there was a tiny logic part which controlled directionality of the coolant loop buried deep within it that had malfunctioned, so it was trying to heat & cool at the same time. unfortunately, it would cost $2500 to dismantle the heatpump, drain and recycle and replace the coolant, replace the cheap part, and reassemble. so i raised the crossover point to 40f 2 months ago and am anxiously awaiting new data, which unfortunately only come via my gas bill, with a latency of over a month...", "timestamp": "1579459729"}]}