"The Stiebel Eltron Tempra 29 Plus Tankless Water Heater features exclusive Advanced Flow Control German patented technology invented by Stiebel Eltron to automatically maintain water temperature for constant comfort. It’ll reduce flow slightly if hot water demand exceeds capacity to ensure that hot showers will never be interrupted. Tempra 29 Plus will typically use 15-20% less energy compared to conventional electric tank water heaters. Although, it’s possible to save significantly more energy depending on personal home usage habits. The difference is that conventional tank water heaters continually store hot water, and as a result, lose 15%-20% of the total energy consumed to the environment around them. This is called standby heat loss. Tank water heaters that use gas or oil are even less efficient, because they also lose heat through their vents to the outdoors. Our tankless water heaters do not need venting, and will not store hot water, waiting for you to use it. They operate on-demand to provide continuous and endless hot water when you need it, and not waste energy when you don’t. CERTIFICATIONS INCLUDE - ANSI/UL Std. 499, CSA Std. C22.2 No. 88, ISO 9001, WQA tested & certified against NSF/ANSI 372 for lead free compliance. TECHNICAL SPECIFICATIONS - Single Phase 50/60 Hz; Voltage: 240 V/208 V; Wattage: 28.8 KW/21.6 KW; Min. recommended household electric service 200 A; Amperage draw: 3 x 40 A 3 x 35 A; Number and min. recommended size of circuit breakers: 3 x 35 A (DP); Number of runs and min. recommended wire size (copper): 3 x 8/2 AWG; Max. temperature rises: 92 F/92 F at 1.50 GPM, 87 F/66 F at 2.25 GPM, 66 F/49 F at 3.00 GPM, 44 F/ 33 F at 4.50 GPM, Min. water flow to activate unit: 0.77 GPM/2.9l/min; Weight: 19.0 lb/8.6 kg; Nominal water volume: 0.39 gal/1.5 l; Max. inlet water temperature: 131 F/55 C; Working pressure: 150 PSI/10 BAR; Tested to pressure: 300 PSI / 20 BAR; Water connections: 3/4"" NPT."