How Rinnai’s ThermaCirc360 Hot Water Recirculation Works



Rinnai uses the cold water line as a recirculating loop to save the cost of adding more plumbing


We’ve all been frustrated waiting for hot water to actually get hot. In colder climates—and if the water has a long way to go to your water heater—you may wait more than for a minute or two for hot water to actually reach your sink or your shower. 

This results in a lot of wasted water and money right down the drain. The good news Rinnai has the solution called recirculation, and here's how it works. 

An internal or an external pump allows your Rinnai tankless water heater to push warm water through your plumbing lines at scheduled intervals or on demand, by pushing a button or using motion sensors at the faucet. 

In the video, recirculation is accomplished with a dedicated return line.

That’s great if your home has one but many homes don’t have a built in return line. Adding one can be really pricey and time consuming. But Rinnai has a unique and effective solution for this varied problem. 

Rinnai’s ThermaCirc 360™ technology and its SE+ Series is equipped with a thermal bypass valve, allowing water already in the system to recirculate. 

It flows through the install valve and recirculates back to the tankless water heater through the cold water line. 

ThermaCirc 360 gets you faster hot water at your faucet regardless of your plumbing configuration. 

How cool is that?

—This video is provided by Rinnai, one of ProTradeCraft's advertisers. Rinnai is one of the world’s largest gas appliance manufacturers, specializing in high-efficiency residential and commercial tankless water heaters and home heating solutions. View all of Rinnai's content.



Can this valve be installed on sinks and showers and tubs in the entire house?

Can the Therma 360 be added to an existing Rinnai?

can therma circ 360 be installed to RL94e Rinnai tankless ?


No, ThermaCirc360 is the ability to provide faster hot water through recirculation, regardless of the plumbing configuration.   This is featured in our RUR models and includes a built in pump and the ability to utilize a crossover valve to recirculate if there is not an dedicated return line.  You can achieve recirculation in the RL94e, however it does require a dedicated return line. I hope this information helps.

What happens when someone turns on cold water while the line is being used to recirculate?

Good question and something you rarely see mentioned.

The cold water line has hot water in it - it will come out warm if not hot at first but will get to cold, faster than waiting for hot to travel from your hot water heater without recirc.

Still wastes water but not as inconvenient as the other way around. 

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