Here is a simple way to decide:
– Do you have a pump start relay? If so, you should choose AC-powered version, as DC-powered version is known to not work with certain pump start relays.
– Do you need to power the controller off-grid, like using solar power? If so, choose DC-powered version.
Otherwise you can go with either. the AC-powered version is more expensive if you also buy 24VAC power adapter from us. The DC-powered version is cheaper as the price includes DC power adapter already.