> For economical home use, the best solution to the chiller overhead would seem to be in altering the commercial design by refrigerating the pressure vessel. This should be possible by separating the pressure vessel from the rest of the carbonation unit and installing the vessel in the household refrigerator. The unit could then be operated at lower CO2 pressures. This would require adapting the liquid and gas plumbing on the unit, and the electrical controls, to make them longer and to pass them through the walls of the refrigerator.
I ended up doing something similar - I found a large commercial kegerator cheap on Craigslist and stuck a McCann carbonator entirely inside it. Then I just had to run power and water to it, which is simpler than splitting the carbonator itself into two components. It works surprisingly well (after replacing a bad check valve on my eBay-sourced model).
I sourced a post-mix bar gun from eBay to dispense it, which also lives entirely in the fridge with the carbonator. After learning about how soda systems work, it was also easy to add a bag-in-box soda system. The pumps are cheap used and are powered by CO2, so you need an extra regulator per syrup you want to add, and then run a line for it to the bar gun. The syrup box lives in the fridge with everything else, so it all stays cold (and the fridge is large enough that we use it for extra fridge space and for beer kegs).
The only downsides are that it’s loud (both the fridge compressor and the carbonator) so it lives on the back porch, and the fridge uses more electricity than I’d like (because it’s commercial). If you were willing to spend more money on a similar set up though, you could fix those issues.