Rinnai Condensing
Water Heaters

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Review of Rinnai condensing water heaters RU80 (old RC80) and RU98 (old RC98). Rinnai condensing RU80 and RU98 models are coming from the "Ultra" series and are the most energy efficient models from all Rinnai tankless water heaters.

Rinnai condensing tankless water heaters have the same modern and stylish look as other tankless models. These units can be installed almost anywhere; outside or inside your home, where will compliment the look of your kitchen with other stainless steel appliances.

Condensing Difference

Rinnai condensing water heaters kept the same advantages and benefits of the tankless technology; heat the water on demand, endless hot water delivery, continuous supply of hot water at a preset temperature, simultaneous hot water delivery to multiple appliances without temperature fluctuation and space saving design.

Rinnai condensing technology utilizes two heat exchangers; copper heat exchanger gets the heat energy from the gas burner while the other, stainless steel one gets the heat from the exhaust flue gases. The secondary exchanger is actually used to pre-heat the incoming cold ground water.

The result of this condensing technology is the higher efficiency; EF of 0.82 found on standard tankless units increases to incredible 0.96 found on RU80, and the lower temperature of the flue gases. These models can also be used for home heating, if combined with the hydronic furnace.

Capability to operate with lower temperatures allows Rinnai RU80 and RU98 to use one concentric venting, where the inside pipe is made of PP material. This way of venting makes the installation faster, cost lower and with the zero clearance from combustible still safe.


Video about features and benefits of Rinnai condensing units


Models Review

There are two groups of Rinnai condensing water heaters, designed for middle and large size homes, or homes with up to five bathrooms or applications.

  • Rinnai RU80

  • Rinnai RU98

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Rinnai RU80

rinnai condensing water heaters RU80 indoor model

Rinnai RU80 series is consisted of the two condensing models. Rinnai RU80i is the indoor water heater while the model RU80e is for the outdoor installation, for residential and commercial use.

They are factory set to use natural gas, but can be converted to propane gas.

Both models are EnergyStar qualified as they are designed with the maximum Energy Factor of 0.96. Built as the Ultra-Efficient devices they are able to produce maximum of 152,000 Btus per hour.

Lower minimum water flow rate of 0.4 GPM is great in a situation when you need low flow for shaving or hand-washing, so less energy and water is wasted. On the other side maximum hot water capacity is 8 gallons per minute, which is sufficient for two to three appliances working at the same time. Every Rinnai tankless model may adjust the water flow to maintain the temperature setting, while the outgoing hot water is monitored all the time.

The factory built-in digital temperature controller is very helpfull and convenient to use - it allows you to set, adjust and monitor the temperature of hot water, and check the error code if there is a problem with the unit.

In order to buy Rinnai RU80, it will cost you between $1000 and $1300, which depends on the fuel type (natural gas or propane) and location (outdoor or indoor unit). You can check the prices here on Amazon.com.

Rinnai RU98

Rinnai RU98 outdoor condensing water heater

Rinnai RU98 series is also consisted of two models. RU98i is condensing water heater for indoor installation and RU98e for the outdoor installation (see the picture).

RU98 series offers lower EF than RU80 series, which is 0.95 for both models, but it can heat more as the maximum heat power is up to 199,000 Btus per hour.

It also delivers more hot water than the previous models - maximum hot water capacity is up to 9.8 GPM.

Both models are EnergyStar and therefore, eligible for government tax credit, and rebates from utility companies (where applicable).

As other Rinnai tankless models, Rinnai condensing heaters are built with the green technology in mind, so they will produce much less greenhouse gases, such as NOx and CO2.

Rinnai condensing water heaters are durable and reliable; they can run for over 20 years with no problem. Even if something happens to its elements, they are replaceable, no need to get rid of the whole unit. They are backed up with the 12-year limited warranty on the heat exchanger and 5-year on labor and parts, when used in residential applications.

You can buy Rinnai RU98, either outdoor or indoor type, also natural gas or propane gas unit for approximately $1300 to $1400. All units have great customer reviews which is between 4 and 5 stars.

Safety features

Safety features from below can be found on all Rinnai condensing water heaters.

  • If there is an excessive temperature increase inside the water heater, an Overheat feature will turn the unit OFF.

  • If the burner flame goes out for any reason, Flame Failure will turn the unit OFF.

  • Power Failure will cut the gas OFF if the unit loses the electrical power.

  • Overcurrent protection.

  • Fusible link will break and shut the unit down if the overheat feature does not react when the temperature rises above the maximum allowable.

  • Automatic freeze protection.

  • Rinnai RU80i and RU98i condensing water heaters are already equipped with a condensate trap and condensate drain line.

Every Rinnai condensing model comes with the built-in MC-91 temperature controller, which can set the temperature within a specific range and show the error codes - great for troubleshooting the problems.

For high demand homes, you can connect two Rinnai tankless water heaters with the EZConnect cable to work as one, or up to five water heaters by using the MSA-2M and MSA-2S sets.


Why should you buy one of Rinnai condensing water heaters?

Rinnai tankless water heater was awarded the "Best" in the industry... "...chosen by home builders in Builder Magazine".

Rinnai condensing technology brings the optimum heating and ultra high performance as it utilizes the heat from the flue gases and pre-heats the incoming ground water. The result is an incredible Energy Factor of 0.96.



(Photo credit to Rinnai)

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