Review: Navien NPE-240A Tankless Water Heater

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Navien tankless water heaters have been in the US market for quite some time, I recently installed the latest model in my own home. I live in central Minnesota, in a rural area where until this summer I had not had access to Natural Gas. Two Navien NPE-240A condensing tankless water heaters have now replaced existing, 13 year old, tank water heaters. Here’s my take on the build, installation and overall performance.

Dual Navien NPE-240A mechanical-hub aune plumbing

First off, as with all tankless water heaters careful consideration must be taken to calculate needed performance values such as total flow rate needed, gas supply available, venting options, recirculation requirements and water temperature   delta-t.

The Navien NPE-240A has a minimum input of 19,900 Btu/h with its maximum topping off at 199K. The negative pressure gas valve and fan with dual venturi operation allows for better adaptability to low gas pressure applications. Operating gas pressures of 3.5” w.c. – 10.5” w.c. are required. The dual stainless steel heat exchangers are an industry exclusive [at time of posting this review].

2” & 3” 2 in or 3 in PVC, CPVC, Polypropylene
 & Special Gas Vent Type BH (Class II, A/B/C) are listed as optional venting sizes and materials for both the intake and exhaust.

The NPE-A models features the “Comfort Flow” built-in recirculation system that monitor use patterns and closely match the hot water needs of the home or commercial building in an effort to eliminate the “cold water sandwich” that plagued the early tankless installs for so long. A built-in buffer tank and recirc pump are included.

The NPE-240A model has ¾” water, recirculation and gas connections. The unit comes equipped with a standard 120V appliance cord [installed] and operates between 200 and 300 watts (max 3 A with external pump connected).

The typical safety devices included are a flame rod sensor, ignition operation detector, water temp high limit switch, power surge fuse and an exhaust temp high limit sensor.


Navien NPE 240-A mechanical-hub

I have to point out that the overall size of the NPE-240 is rather large when compared to other top brands on the market. To be honest, this is a positive in my opinion. The larger cabinet affords more room inside. Where other tankless models are ultra cramped, this one is slightly less cramped. A little larger cabinet and heat exchanger adds to the total weight, the NPE-240A (w/ hot water circ pump & buffer tank) tips the scale at 82lbs. The cabinet measurements are as follows: 29” tall, 17” wide, 13” deep.

I have been installing and servicing tankless water heaters for a little over fifteen years. In that time dozens of models have came and went, none of them had the built-in features that the NPE has. The ability to operate under such low gas supply pressure, link up to 16 units in one group easily with a simple cable and control configuration. Common venting is a breeze too, though standard individual venting in 2” PVC/CPVC/PP can go as long as 60’. The 0.01 minimum flow rate for the “A” model is outrageously low when compared to the units we were installing as recent as 5 years ago.

In summary:

My family hasn’t noticed any changes since I made the switch to tankless. The installation was extremely simple, more so than other models I have installed in the past. I’m impressed by the easy to read and access front control and just how quiet the NPE model is; it’s nearly silent.

I’ll update this review if any issues arise over the next year. Thanks for your time, I hope you found this useful.

Eric Aune

Aune Plumbing, LLC


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