The Best Tankless Hot Water Heater

Tankless water heaters have risen in terms of popularity over the years. The reason for this is because these devices deliver hot water nearly instantaneously. It has a considerably longer service life than the traditional tank style counterpart. You also get the its ability to fit into tight spaces which is a very good plus. Furthermore, it has a certain environmental appeal. That’s why these tankless systems are a smart choice for many home owners. So if you are looking for the best tankless hot water heater, we recommend you get the Rinnai RUC98iN Ultra Series Natural Gas water heater. You want to know why? Keep reading this article.

Main Characteristics

The hot water heater is an indoor gas tankless water heater that is suited for both residential and commercial applications. It uses propane or natural gas (depending on which type you choose) and has multiple venting options. Rinnai has equipped the RUC98iN with two venting options, the concentric-PVC and twin-pipe. You can choose any of the two options depending on which you find easy to install. If you live in a large house or have a big family, you can rest assured that this heater can easily supply searing hot water to multiple faucets and showers simultaneously, with no interruption at all. To make it clear, this heater can provide hot water at a flow rate as high as 9.8GPM. The flow rate stems from the natural gas intake which varies from 15,200 to 199,000BTU. Aside from that, the heater's hot water flow rate range is also very wide at 0.26 to 9.8 gpm. It has a minimum activation flow rate of only 0.4 gpm. These figures mean that this Rinnai tankless water heater can power multiple faucets and showerheads and still can be used in multi-bathroom households without interruption to hot water flow. Of course this will depend if you can afford to pump it its required gas. That makes this water heater very versatile because it will give you your desired water flow rate.

Pros and Cons


  • Even though it is bulky, it occupies less space than other water heaters
  • Highly energy efficient, with an energy rating of 0.95
  • Provides a huge hot water flow rate
  • Able to provide hot water to multiple faucets and showers simultaneously
  • Very durable
  • Versatile


  • Expensive
  • Difficult to install and a bit bulky


This tankless hot water heater is 26 inches tall, 10 inches thick and weighs 61.7 pounds. It is a bit large for a tankless water heater. Although it is compact and has a sleek design, it is not a lightweight water heater as you can see. It has a gunmetal gray exterior. The controls are located on the lower lip of the front panel. The controls include a power button, water temperature and gas control buttons, and a digital display. Aside from it being able to control the temperature of hot water coming out of the unit, you can also lock the temperature button to prevent unauthorized access.

Special Features

What makes this tankless hot water heater special is it has bigger inlets and outlets than most gas tankless water heaters. It is also bigger and heavier, but provides more powerful. Even though it is very powerful, it just has an energy factor of 0.95 (which is higher than the average for water heaters powered by gas, we admit), it is still an energy efficient water heater. As mentioned above, this tankless water heater can supply enough hot water to multiple showers and faucets in a house with several bathrooms and will not suffer from interruption to the flow of hot water. This is probably its main selling point. This feature is mainly attributed to the fact that this heater has a minimum to maximum gas burn rate varying from 15,200 to 199,000 BTU. This is considered to be a very wide range in terms of tankless gas water heaters.


The Rinnai Standard Limited Warranty will cover any defects in materials or workmanship when the product is installed and operated according to Rinnai written installation instructions, subject to the terms within this Limited Warranty document. Check the document for the exact warranty details.


This why the Rinnai RUC98iN Ultra Series Natural Gas water heater is considered the best tankless hot water heater. With its capability to supply unlimited hot water, savings in the energy and water consumption, great space-saving design, and environmental benefits, it is just hard to say no to this device. So if you’ve got the budget, don’t hesitate to get this unit. It is an excellent investment.

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