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Tankless Water Heaters

Rinnai Tankless Solutions Give You the Power to Live Better

An endless supply of hot water, whenever you need it—even for multiple tasks at the same time. Tankless Water Heaters revolutionize comfort, energy efficiency and convenience.

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Condensing Tankless Technology

The Rinnai Ultra Series


Delivering our most energy-efficient performance, the Ultra Series features a condensing design with two heat exchangers to maximize hot water output. RUR Models featuring ThermaCirc360 include built-in recirculation pumps to offer faster hot water.


  • ENERGY STAR® qualified - Energy Factor of up to .96
  • RUR Models featuring ThermaCirc360 offer faster hot water with an integrated recirculation pump and internal bypass line - with or without a dedicated return line
  • Available in five sizes: 130,000,152,000, 160,000, 180,000 and 199,000 BTU
  • Allows for either Concentric Polypropylene or dual-pipePVC/CPVC venting, providing the most venting flexibility in a single application of any manufacture
  • Easy maintenance is achieved with isolation valves *
  • *Isolation valves included on select models.

ThermaCirc360 (RUR Models)

RUR Ultra Series Tankless Water Heater

Rinnai introduces the first and only tankless water heater in the industry to offer both concentric and PVC/CPVC venting and integrated recirculation on the same model.

Imagine turning on a shower and getting hot water almost immediately. Considering the average family loses precious time and numerous gallons a day waiting for water to heat up, that would be an invaluable change in routine. If you’re tired of standing idly by while time and water go down the drain, Rinnai has five words that are sure to inspire you: Faster Hot Water Is Here!

Bringing Faster Hot Water Home.

Our focus on enhancing homeowners’ lives by changing the way water is heated has created an exciting breakthrough in recirculation that puts faster hot water a turn of the knob away.

Rinnai’s ThermaCirc360 (RUR Models) use thermal bypass technology that includes an integrated recirculation pump, an internal bypass line inside the model and a thermal bypass valve, and MC-195T 24-Hour Digital Controller provided inside the box to send unlimited hot water wherever and whenever it’s needed, all in one comprehensive solution. By keeping a steady supply of heated water in the supply line during active circulation periods, the RUR's ThermaCirc360 makes hot water rapidly available in showers, sinks and appliances such as washing machines and dishwashers.

Wait Less, Waste Less.

Getting hot water faster creates significant benefits above and beyond the convenience of saving time. Recirculation means less water and money down the drain, saving on natural resources and the utility costs related to gas and water usage. And you can save even more energy by programming the 24-hour digital controller that’s included in the box. It enables the scheduling of multiple recirculation events throughout the day to align with usage patterns and ensure hot water is available at the fixtures during peak demand times such as early morning before work and school.

With the typical U.S. home wasting potentially thousands of gallons of water annually waiting for hot water, the RUR’s fast-track delivery system pays off at the faucet and in the budget. And the convenience and comfort of hot water recirculation is an attractive feature that adds resale value to a home.

Adaptable to plumbing systems with or without a dedicated recirculation line, the RUR Models with ThermaCirc360 are the only tankless water heaters to feature both Concentric and PVC/CPVC venting options on the same model, offering the ultimate flexibility.

The pleasure of faster hot water is truly at hand. And big water and gas savings are on tap, too. Thanks to Rinnai’s smart recirculation technology, there is less waiting and less waste.

Rinnai Tankless Water Heaters deliver trusted quality and proven reliability you can count on. From efficient, durable products to experienced support, there is simply no better choice than Rinnai.

  • Wide range of quality product offerings
  • Easy, safe ventilation options
  • 24/7 technical support for professionals
  • Engineering application support for commercial customers
  • Industry-leading recirculation capabilities
  • More venting solutions on the same model

Saving Time, Water and Money with Smart Recirculation.

Recirculation in action…How the RUR with ThermaCirc360 works.

Dedicated Return Line

Rinnai is the only manufacturer to offer a tankless model, the RUR with ThermaCirc360, which is easily adaptable to plumbing systems with or without a dedicated recirculation return line right out of the box.

In the Dedicated Recirculation Line mode, the integrated pump circulates water from the tankless water heater through the hot water supply line and back to the tankless water heater via the dedicated return line. A temperature thermistor installed in the RUR’s inlet pipe is utilized to control the on/off sequence of the integrated pump.

In homes with a dedicated return line, the RUR with ThermaCirc360 also provides for additional control of the integrated pump through Rinnai’s time and temperature-based Comfort or Economy mode. In the Comfort mode, the pump on/off intervals can vary from 9 to 31 minutes depending on the temperature setting. When the return water reaches the temperature called for at the tankless water heater, the pump will turn off. In the Economy mode, the pump on/off intervals are less frequent and vary from 18 to 62 minutes depending on the temperature setting, providing additional energy and cost savings.

MC-195T 24-Hour Digital Controller

Both indoor and outdoor RUR models include a MC-195T 24-Hour Digital Controller, allowing you to adjust the timing and duration of the circulation system operation for maximum energy savings. Rinnai Circ-Logic technology built into the water heater operates the pump during active circulation periods.

Crossover Valve

In applications where a dedicated recirculation line is not available or difficult to install, the RUR Tankless Water Heater utilizes the Crossover mode of hot water recirculation. The RUR’s integrated recirculation pump, internal bypass line and thermal bypass valve, which is included as standard with every RUR model, make the Crossover mode of recirculation possible. The valve is installed between the hot and cold supply lines on the furthest fixture in the plumbing line from the tankless water heater. The cold water line is then used temporarily as the return portion of the circulation loop.

In the Crossover mode, the integrated pump circulates water from the tankless water heater through the hot water supply line, through the thermal bypass valve, and back to the tankless water heater via the cold water line. When hot water is detected at the valve, the water flow through the thermal bypass valve reduces down to barely a trickle, continuing to sense water temperature in the line. The pump will continue to operate and recirculate inside the water heater only until the end of the time interval and will restart at the beginning of the next interval. Installation of the bypass filter that’s included in the box is used in the Crossover mode to allow the internal circulation of water through the water heater after the thermal bypass valve has closed.

In Crossover mode, the RUR again provides for additional control of the integrated pump through time-only based Comfort or Economy mode settings. In Comfort mode, the typical pump on/off intervals will vary depending on the length of recirculation loop used. For a short loop, the pump will be on for 8 minutes, off for 4; long loop, on for 16 minutes off for 4. In Economy mode, again the typical pump on/off intervals will vary depending on the length of recirculation loop used. For a short loop, the pump will be on for 8 minutes, off for 10; long loop, on for 16 minutes, off for 10, providing additional energy and cost savings.

Regardless of the hot water recirculation method used, the end result is the same: During active circulation periods, hot water is always available as it circulates from the hot water line back to the Rinnai RUR Tankless Water Heater.