A Better Tankless Water Heater? Navien Tankless Water Heater – A Product Review

Navien tankless water heaters have a couple of great features that make it an outstanding choice for many homeowners. It appears they have solved several of the problems most tankless water heaters are saddled with.

Tankless water heaters a becoming quite popular, largely to due the perception that tankless water heaters are green and save energy. However, since tankless heaters require longer wait times to get hot water to the fixture, they can end up wasting water. Another problem with them is obtaining a small stream of warm water is very difficult.

Tankless units require a minimum flow rate to turn on, typically requiring ½ gallons per minute to ¾ gallons per minute. To get warm water you end up needing to mix cold water with the hot water and thus you can end up with a minimum flow of over a gallon a minute.

Navien has tankless water heaters with a built-in buffer tank and circulating pump. According to the Navien literature this feature allows you to use as little as .1 to .2 gallons per minute and the water heater will keep putting out hot water. With these models your hot water will reach your fixture more quickly since there is water already hot waiting to be sent to the fixture as soon as you turn on the hot water faucet.

This system also eliminates what is known as the “cold water sandwich” which is a common problem with tankless water heaters.

These tankless heaters can circulate the water internally between the heat exchanger and the buffer tank, or you can even connect them to a traditional dedicated return line and the internal pump will circulate hot water so you have instant hot water at your fixtures.

There are three “A” models, the NR-180A, the NR-210A, and the NR-240A offering a good range of flows for just about any residential application.


From the Navien website it sounds like the heater is well constructed. It has stainless steel heat exchangers and boasts a 98% efficiency, the highest in the industry. The exhaust temperature is low enough to use PVC for the venting, up to 100 feet long.

The three Navien water heaters that have these features are as follows:

NR-240A
Input 17,000~199,000 BTU/h
Thermal Efficiency 98%
Energy Factor 0.95
Flow Rate At 35˚F Rise : 11 GPM
At 45˚F Rise : 8.6 GPM
At 77˚F Rise : 5.1 GPM

NR-210A
Input 17,000~180,000 BTU/h
Thermal Efficiency 98%
Energy Factor 0.94
Flow Rate At 35˚F Rise : 10.0 GPM
At 45˚F Rise : 7.7 GPM
At 77˚F Rise : 4.6 GPM

NR-180A
Input 15,000~150,000 BTU/h
Thermal Efficiency 98%
Energy Factor 0.94
Flow Rate At 35˚F Rise : 8.3 GPM
At 45˚F Rise : 6.5 GPM
At 77˚F Rise : 3.8 GPM



Navien claims its condensing technology uses less gas than standard storage tank type water heaters and that it results in lower CO2 Emissions than other brands.

It’s further disclosed that the Navien heaters dramatically reduce NOx emissions, giving it the lowest emission level in the industry. Interestingly Navien states that its Condensing 98% tankless water heater has become more eco-friendly by dissolving NOx in condensed water to neutralize the alkaline sewage in your house, improving water quality. Interesting concept, but is it anything significant? I don’t know the answer to that.

All Navien heaters will work great with hot water demand systems, and with the A models the low required turn on flow will probably allow it to work with just about any of the hot water circulating systems and demand type systems on the market.

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