Are you proposing that we capture heat this way to warm houses (in which case it's a terribly ineffective and inefficient system) or to actually raise the outsi

Are you proposing that we capture heat this way to warm houses (in which case it's a terribly ineffective and inefficient system) or to actually raise the outside temperature? If you're proposing the latter, there's just no way. Water might store 400 times as much heat per unit as air, but there's an absurd amount of air hovering around a town and an enormous area that air mixes with constantly.