Plumber installed tankless Navien heater - Don't have model # handy right now. Replaced an AO Smith cyclone unit that could not keep up on busy days. This unit feeds all my solution mixing stations and Ts into a cold water line so water at the stations is warm, not hot and I adjust it for outside temp. Warmer in winter not as warm in summer. Bottom line was at 100+ CPH the AO smith could not keep up and this one does. The AO Smith replacement would have been about $6000 . This unit costs about $1500.00 . Planned plumbing in case I might need 2. But I don't.