According to a press release by Rinnai, a leading manufacturer of gas applicances, two new products are being introduced to their Condensing Tankless Ultra Series. Known as the “RUR” models, the RUR98e and RUR98i are both 199,000 BTU/hr input. The “e” designates outdoor installations, the “i” for indoor installations. The biggest features that Rinnai is showcasing are an internal recirculation pump, bypass line, and thermal bypass valve.
Tankless heaters only fire when a fixture opens, or in other words, when flow is detected. A continuously operating recirculation pump on the return line voids the warranty for most brands and defeats the purpose of the energy savings that an “on-demand” tankless heater provides. This has been a longstanding problem with tankless. Since there is no recirculation pump on the return line, it becomes imperative to locate the heater close to the fixtures so that it does not take a long time for hot water to reach the end user. This unfortunately is not always practical.
Rinnai states that with the RUR, no dedicated return line is needed because the use of “cross over” technology. The RUR control has a timer that allows the user to schedule recirculation throughout the day. Although still limited to certain distances, this is a much needed solution for tankless market share growth. Other manufacturers boast varying technologies with the same purpose of addressing the recirculation problem. For example, Navien’s CounterFlow technology incorporates an internal pump with a buffer tank. As tankless continues to increase in popularity, there will be more than one way to solve recirculation. The RUR will be available in January 2015 so there is little technical information available now. I look forward to reading more on how it works.
Photo Courtesy of Rinnai