Think it depends a lot on how large your system is. As I noted back in the early posts in this thread, I had arranged for Wann to build a heat/cool exchanger for my nominally 1,000 gallon system. Although my heating cost aren’t terrible (since my main display is 1” acrylic) I was quite keen to dispense with the 3/4 HP chiller. Unfortunately what I got from AE never worked properly. After months of waiting, and lots of ‘promises’, I got the heat exchanger but not the control board. A couple more months and the control board finally showed up. Had all sorts of quality control issue with the latter, but the bigger problem is that the exchanger appears to be undersized. Unlike the one you showed from Facebook, mine has just two long loops of titanium, not the packed coils. Simply not enough to be able to get adequate heat exchange with the cold water. Wann said he’d build me a larger replacement, even going as far as it would ship next week .... that was October.
Heating works, but only saves you money if it’s a lower cost fuel. Buddy of mine did a HW loop, but his house heater is electric, so hard to see how that makes sense . If you are on a well, cooling can work if you have a properly sized heat exchanger and aren’t bothered by wasting water .... though I suppose it ends up back in the aquifer eventually. Means cycling the well pump more often, which means more wear and tear.
I think for most moderately sized systems 300 gallons or less, standard stick heaters and a reasonable chiller probably is the best approach.
