2021 Rinnai Tankless Series & Models Rinnai organizes its tankless water heaters by efficiency (Uniform Energy Factor or UEF) and features: SENSEI RX Series (Condensing) • RXP Models (RXP199iN, RXP160iN): Features a 0.98 UEF rating with a built-in recirculation pump and Smart-Circ technology. • RX Models (RX199iN, RX180iN, RX160iN, RX130iN): High-efficiency units with a 0.98 UEF rating, Smart Sense gas valve (natural gas or propane convertible), and a Quick Flush feature. • RUS Models (RUS75eN/eP, RUS65eN/eP): Outdoor condensing units with a 0.90 UEF rating. • RUCS Models (RUCS75iN/iP, RUCS65iN/iP): Compact indoor condensing options with a 0.85 UEF rating. RE Series (Non-Condensing) • RE & REP Models (including RE199, RE180, RE160, RE140): Traditional non-condensing indoor (i) and outdoor (e) variants with UEF ratings around 0.81 to 0.82, suited for small-to-mid-sized hot water demands.