Rheem's under the sink, on-demand recirculating pump kit provides instantaneous hot water where you want it and when you need it. As a bonus, this kit helps save up to 12,000 Gal. of water per year by reducing the amount of water running down the drain while waiting for hot water. This under the sink option is a perfect solution for adding instant hot water to an existing water piping application. Application - This model is perfect for retrofits and new construction. Engineered for use with all Rheem Tankless and Tank Type water heaters.