Rinnai RU199iN Tankless Water Heater vs Rinnai Sensei RX199iN Tankless Water Heater

Both are 199,000 BTU condensing Rinnai Sensei units that deliver continuous hot water for large homes. The RX199iN is the newer Pro Build platform: it runs on natural gas or propane without a conversion kit, reaches a higher 0.98 UEF, and can be mounted outdoors with the Versa Vent cap. The RU199iN is the older indoor-only Sensei with a 0.93 UEF and a slightly lower rated flow. Buy the RX199iN unless you find the RU199iN at a clear advantage and only need indoor natural gas.

• Choose the RU199iN if you need an indoor natural gas unit only and want the established Sensei model that installers know well.
• Choose the RX199iN if you want the higher efficiency, propane flexibility, or the option to vent outdoors later.