Keep in mind that I would have the same problem with a tank water heater. That is, it takes a long time to get water at the fixture.

Space in the box is a concern.

I'm thinking more along the lines of a thermostatically controlled pump, perhaps in conjunction with a timer so that it only circulates at certain times of day. These are available.

The ones I've looked at require 240V which would be a bigger deal. And would only fix the problem in one fixture.

Good points. The selling point on tankless for us was the unlimited supply of hot water more than the idea of not reheating water we weren't using.

I see your point about wasting hot water when we want cold. It's kind of the opposite of what we have now--wasting cold to get hot. Maybe that's a vote for dedicated loop if I decide to recirculate.

Thanks.