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Nanien Tankless Water Heater

/Nanien Tankless Water Heater
Nanien Tankless Water Heater 2018-08-13T16:35:45+00:00

Navien has three “A” models, the NR-180A, the NR-210A, and the NR-240A.


I’m not a big fan of tankless water heaters. I don’t need endless hot water and I often use small flows of hot water which is difficult for tankless water heaters to provide.  Typically they require .5 to .75 gallons per minute of hot water flow to turn on and to stay on.  That makes it very difficult to get a small stream of warm water.

Enter the Navien Tankless water heater.  The “A” models have a unique feature, at least one I have not run across before, 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.

This also eliminates the fabled “cold water sandwich” which tankless water heaters are known for.  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.

Hot Water Recirculation with Tankless Heaters

I’m not advocating hot water circulating systems, I prefer demand systems, but I’m sure there are some people out there that would find it useful.  It’s the low flow capability of these heaters that I think is a really great thing.  It will result in water saved.

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.

Here are the specifications for the three models with the built in buffer tank and circulating pump.

Navien Model 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

Navien Model 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

Navien Model 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’s condensing technology claims to use less gas than conventional water heaters and that it results in less CO2 Emissions than other brands of tankless water heaters.

The Eco Pre-mixed Burner dramatically reduces NOx emission levels, making it the lowest emission levels in the industry.  Interestingly Navien states that it’s 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.  Sounds good, but I wonder if it is significant in any way?

I’m not saying that the Navien models are the best tankless water heaters, I don’t know how they hold up over time or much of anything else about them.  But I do think they have at least in my opinion the best idea for a tankless water heater.

The Navien models will work great with demand systems like the Chilipepper, and with it’s low required turn on flow it will probably work with just about any of the hot water recirculating systems and demand type systems on the market.