Rinnai RU Vs RUR Vs RSC: What Are The Differences?

Rinnai is the leading tankless water heater manufacturer for more than a century. The company offers highly efficient RU, RUR, and RSC models. These water heaters are similar but have distinct properties, which we have researched for you.

The main difference between these models is their recirculation technology. The RU model uses the Circ-Logic system, the RUR has the Circ-Logic 360, and the RSC uses an upgraded version of the RUR with Smart-Circ technology. 

These models also differ in the following areas:

  • Number of fixtures serviced
  • Power range
  • Uniform energy factor 
  • Water flow

The models, in comparison, are all efficient, but there are slight differences. It is good to know the differences to choose the most appropriate Rinnai water heater for your home. Read further to learn the Rinnai water heater models.

Home electric heating boiler, Rinnai RU Vs RUR Vs RSC: What Are The Differences?

Rinnai Tankless Water Heater Models

Rinnai has been the top tankless water heater company for over 100 years. The brand claims it has two times more lifespan than other traditional tanks. They are highly durable due to the brand's commercial-grade manufacturing.

You will never run out of water with the Rinnai heaters. The heaters have advanced technology and energy-efficient features to provide on-demand hot water. Also, you can remotely program and monitor the heater using the PRO App and control-r WiFi feature.

The Rinnai water heaters can run on natural gas or propane. You also have the option to install the heater anywhere inside or outside while consistently providing several places at home.

If you have a Rinnai heater at home, you can use it for various household applications. You can fit the device in every space because of its compact size. The heaters are energy-efficient because they heat water only when you need it.

Although the production technology is the same for the Rinnai models, they have distinct features. You can find out about the models below.


The RU is one of the two models under the SE+ condensing series. It is an Energy Star-qualified device for energy-efficient use. You can connect the device to WiFi to control and access services. Also, you can install it indoors or outdoors, depending on the RU model.

Aside from connectivity and installation location, RU is SCAQMD Approved, which emits ultra-low NOx.

This model is different from the other models due to the following:

  • Recirculation technology - Circ-Logic
  • Uniform energy factor - ranging from 0.91-0.93
  • Power range - 130,000 to 199,999 BTU
  • Areas provided  - 2 to 6 fixtures (medium to large households)
  • Water flow - 7-11 GPM

The RU is a good choice for new households. The limited warranty for the heat exchanger of SE+ models is 15 years (or 12,000 hours, whichever comes first) for residential use. Only correctly installed units in the United States can avail of the warranty.

Check out this Rinnai RU water heater on Amazon.


The RUR is the other model in the SE+ condensing series. This model is also Energy Star-qualified and WiFi-capable, but there is a slight difference compared to the RU model.

The differences are the following:

  • Recirculation technology - built-in Circ-Logic 360 system
  • Uniform energy factor - ranging from 0.93 (can go as high as 0.95-0.96)
  • Areas provided  - for large, high-demand households
  • Power range - maximum of 199,999 BTU
  • Water flow - from 9 to 11 GPM

In June 2022, the RUR models transitioned to the RSC model.

Buy this Rinnai RUR unit from Amazon.


The RSC model is the new and improved tankless water heater of Rinnai. This model will continue delivering high-quality, efficient hot water for your household needs. The improvement not only gives customers better service but also the ease and cost-effective installation by the PROs.

As an upgrade of the RUR model, it has the same features and capabilities. What makes it different from the other two models is the following:

  • Recirculation technology - Smart-Circ intelligent recirculation

The heater uses the Smart-Circ technology to learn your household's heating, pumping, and recirculation patterns in seven days.

There are two recirculation modes of the Smart-Circ technology, namely:

  • Crossover mode - This mode uses a thermal bypass valve for connections without a dedicated return line.
  • Dedicated mode - You can easily recirculate the water if you have an exclusive return line.

Get this Rinnai RSC tankless water heater indoors on Amazon.

With the new and improved water heating technology, the RSC is more efficient because of the multi-speed DC pump for a higher flow rate and better head pressure. In that case, you can be more flexible with the heater operation.

Compared to the other models, the RSC is easier to install, and serviceability is favorable.

Which Fuel To Use For Rinnai Water Heaters?

Row of gray natural gas meters at an apartment complex

You can use natural gas or propane to heat the water. The water heater models vary with the allowed gas type.

If you want the cheaper option, choose propane. Natural gas is expensive because it burns faster than propane. Hence, you will need twice the amount of natural gas as propane.

You can use natural gas if you have a pipeline to your home. After all, both are cheaper than electricity.

Other than the two energy sources, Rinnai tested the units with Hydrogen-Enriched Natural Gas (HENG), which is a mix of natural gas and hydrogen. The HENG can further lower the carbon intensity of natural gas and is more environment-conscious.

Rinnai is pushing the use of clean energy sources to create a healthier way of living for both humans and the environment. The sources help reduce carbon monoxide and nitrogen oxide emissions while maintaining the heaters' efficiency.

Where To Install Rinnai Water Heater?

Shower and electric water heater in the bathroom

There are many locations where you can install your water heater. You can install the water heater either inside or outside your home.

If you install it indoors, you can place it anywhere because of its compact size. You can install the unit under sinks,  storage areas, pantries, or other small spaces.

Installing the heater outside is also feasible. However, when it is out, you must mount and protect the unit from rain, direct sunlight, insects, and cold temperatures.

When selecting the location, you should evaluate existing plumbing connections, the electrical central panel location, and the proximity of the areas where you need hot water. Also, keep the unit away from areas with combustible materials.

How Do Rinnai Tankless Water Heaters Work?

Rinnai tankless water heaters will provide hot water when and where you need it. Intelligent heaters give you a hassle-free hot water supply without wasting energy. Also, the water stays hot even after using it.

Here is the process of how the Rinnai tankless water heaters work:

  1. The unit detects water flow.
  2. A flame heats the two heat exchangers.
  3. The water preheats to the desired temperature as it passes through the second heat exchanger.
  4. The heater continues heating the water as it passes through the primary heat exchanger.
  5. Then, you release the hot water from the fixture where you need it.
  6. The flame output maintains the water temperature while in use.
  7. After using the water heater, the flame turns off, and the water flow stops.

You get unlimited hot water without waiting for it to reheat. The recirculation technology maintains the hot water temperature for the subsequent use.

The models mentioned in the post belong to the condensing series. The units have a second heat exchanger, wherein the heat exhausted loops back to the system to provide hot water efficiently. With this feature, you must drain the condensation at the bottom of the heater.

Furthermore, the Rinnai heaters have WiFi capabilities. With a smartphone or voice-activated device, you can control, monitor, and program the heaters using the control-r module.

Instantaneous gas hot water heater on the side of a house

Why Choose Rinnai Tankless Water Heaters?

Water Heater on white bathroom wall

Rinnai offers a wide range of durable and efficient tankless water heaters. The SE+ condensing series is the best among Rinnai's water heater lineup. With advanced technology, the units can provide hassle-free and on-demand hot water from anywhere in the household.

Rinnai is one of the best water heaters in the market. There are numerous benefits you can enjoy when installed correctly. You also get quality after-service by contacting their PROs.

In Summary

Home electric heating boiler

Rinnai has three tankless water heater models in the SE+ condensing series. These are the RU, RUR, and RSC. The models have similar functions and characteristics, but they have some differences. The main difference among the models is the recirculation technology.

Regardless of which Rinnai heater model you choose, your household will benefit from the hassle-free and on-demand hot water.

You might like to read these other related posts:

Rinnai Tankless Water Heater Beeping—What’s Wrong?

Rheem vs. Rinnai Tankless Water Heater – Which To Choose?

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