Rinnai R75LSi Indoor Tankless Water Heater (Discontinued)

The Rinnai R75LSi is a 180,000 BTU indoor non-condensing tankless water heater, now superseded in Rinnai's current catalog by the RL75iN Sensei platform. The R75LSi remains widely available through wholesale and used markets, with parts support committed by Rinnai through 2030. It is positioned as a discontinued model still in service in many residences manufactured 2010 through approximately 2020.

Specs: 180,000 BTU natural gas input (LP variant available as R75LSiP), UEF 0.82 (non-condensing), 7.5 GPM at a 35°F rise, copper heat exchanger with stainless secondary, 4" Category III stainless steel B-vent. 12-year warranty on the heat exchanger from original install date, 5-year on parts. For a unit purchased new, the warranty has typically lapsed if the unit is now in service longer than 12 years; for a unit purchased used, warranty does not transfer.

The R75LSi is a unit that buyers encounter in one of two scenarios: replacing an existing R75LSi that has finally failed, or buying used through marketplace channels. For the first scenario, the more common upgrade today is the current RL75iN, which carries the same install footprint and venting requirements with iterative improvements to the control board and the user interface. For the second scenario, used R75LSi units should be priced at no more than 30% of the new RL75iN price given the lack of warranty transfer and the unknown service history.

Service: Rinnai's dealer network supports the R75LSi for parts and repair through 2030. Common service items are the flow sensor, the igniter, the flame rod (cleaning, not replacement), and the inlet water filter. For units with consistent fault codes around year 12, the typical repair-vs-replace decision favors replacement with the current RL75iN platform.