Replacement parts for Rinnai gas water heaters can be purchased online from home improvement supply retailers such as Houseneeds, National Builder Supply and Build.com. Internet auction sites such as eBay also frequently contain listings for new and used Rinnai gas water heater replacement parts.
Users searching the Build.com site for Rinnai water heater replacement parts can sort results based on price range and the type of part needed. Each part's listing contains a picture or rendering of the part, a description of its purpose and function, its price minus any site-applied discounts and a section of user reviews. Each review consists of a quantitative satisfaction ranking, in the form of one to five stars, and a qualitative written account of the user's experience with the part. As of March 2015, Houseneeds and National Builder Supply do not feature customer ratings in their listings.
Auction sites such as eBay also do not contain user ratings of products because there is no standard way to catalogue the items being sold on the site. However, eBay does allow its users to rate sellers. Once a user has initiated a purchase with a seller, she has the option to provide positive or negative feedback based on the transaction.