Navien NR Condensing 98 Residential Tankless Water Heater Review

The Navien NR Condensing 98 residential tankless water heaters are available in three base models, the NR-180, NR-210, and NR-240. Navien offers a unique add on option for a built in tank and recirculation pump to each of these models by adding the suffix “A” to the model number with the NR-180A, NR-210A, and NR-240A models. A common complaint among tankless water heater users is the wait for hot water each time you turn on hot water at a faucet and the lack of hot water at low flow rates too low to trigger the tankless unit to fire. The built in tank and recirculation eliminates this problem by having hot water in the piping close to your point of use at all times. The Navien NR Condensing 98 residential tankless water heaters offer an efficiency of 98%, which is achieved by using a modulating burner in conjunction with a condensing heat exchanger. The modulating burner fires at a variable rate adjusted by how much heating is needed to heat the water you are using without wasting fuel in a process very similar to using the accelerator pedal in your car adjusting to the flow of traffic. The burner is a premixed burner where the fuel and air are mixed in a fan with precise mixtures of fuel and air to maintain a very clean efficient burn that is very low in the output of NOx and CO2, which is a component of smog and global warming. The condensing heat exchanger utilizes the heat of the discharging flue gases to preheat the incoming cold water soaking so much of the heat out of the flue gases that moisture in the gases actually condense to water which is then used to absorb NOx and when discharged help neutralize alkaline sewage from the home. The Navien NR Condensing 98 residential tankless water heaters are recognized as an energy saving green technology and are eligible for rebates, grants, and even a 30% income tax credit up to $1500 under the programs of the American Recovery and Reinvestment Act of 2009.

The Navien NR Condensing 98 residential tankless water heaters feature a stainless steel heat exchanger which Navien claims is up to 4 ½ times more life and resistance to erosion over the copper heat exchangers used by other manufacturers. The Navien NR Condensing 98’s also have a cool flue gas discharge, which can be discharged through PVC, a three stage premix burner controlled by dual microprocessors utilizing air pressure and gas pressure sensing to provide the optimum fuel/air mixture modulated to your exact needs.  The dual microprocessors also monitor safety functions and tests themselves as well. The Navien NR Condensing 98 residential tankless water heaters can be fired on either Natural Gas or, LP Gas with an easy conversion when setting the unit up. The “A” models feature a built in tank and recirculation pump which can provide instant hot water at fixtures through out the home at any flow level without having to flow a minimum amount of water to fire the unit and waiting for the unit to detect a flow, fire, then the heated water to travel through the pipes to your point of use, units without the recirculation feature require a minimum flow of 0.5-gpm to fire the unit. The NR-10DU remote controller has a backlighted LCD screen, which reads out diagnostics and error codes as well as controlling temperature and recirculation times with inputs via pushbuttons, which can be locked out to prevent unintentional changes. Multiple units can be interconnected in a cascade system to provide virtually any amount of hot water flow you need. The Navien NR Condensing 98 residential tankless water heaters in residential installations are provided with a 15-Year Parts Warranty on the heat exchanger and a 5-Year Parts Warranty on other components, also provided is a 1-Year Labor Allowance.

The Navien NR Condensing 98 residential tankless water heaters three base models have different capacities.

  • The NR-180 fires from 15,000 to 150,000 Btu/h, measures 17”W X 28”H X 14”D weighing 67 lbs. with the “A” model weighing 77 lbs. The NR-180 can produce 3.8-gpm with a 77-degree F temperature rise up to 8.3-gpm with a 35-degree F rate of rise.
  • The NR-210 fires from 17,000 to 180,000 Btu/h, measures 17”W X 28”H X 15”D weighing 77 lbs. with the “A” model weighing 86 lbs. The NR-210 can produce 4.5-gpm with a 77-degree F temperature rise up to 10-gpm with a 35-degree F rate of rise.
  • The NR-240 fires from 17,000 to 199,000 Btu/h, measures 17”W X 28”H X 15”D weighing 77 lbs. with the “A” model weighing 86 lbs. The NR-240 can produce 5-gpm with a 77-degree F temperature rise up to 11-gpm with a 35-degree F rate of rise.
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13 comments on “Navien NR Condensing 98 Residential Tankless Water Heater Review
  1. Louis Howe says:

    The gas line for the heater.Is it a dedicated gas line and the size of gas line.

    • Redwood says:

      Hi Lewis,
      The line to your tankless unit does not have to be a dedicated line, however the gas supply to it does have to be properly sized and may require an upgrade of your gas service in order to meet the demand. I would highly recommend installation by a professional as proper gas flow to the unit and other gas appliances in your home is essential to proper operation. Proper sizing is determined by the supplied pressure, length of the line, fittings used, and btu’s required with a chart used to determine the size. This is not something that I can answer for you so it is best to call a local pro.

  2. dejong says:


    Is it really easy to convert a LP model, say the NR-240A, to Natural Gas? Where could I find the proper kit to do this?

    • Redwood says:

      Hi Dejong,
      Conversion from LP to Natural Gas is a relatively easy task however, for your safety and to ensure proper operation, it should be performed by a licensed professional. Use the Installing Dealer/Navien Service Specialist Finder on the Navien Website to find a trained professional in your area.

  3. JCWinNM says:

    The Navien owners manual says that their units cannot be converted from or to LP/Natural Gas in the field. I am confused. The discussion above indicates it is possible. Who is right?

    • Redwood says:

      Hi JC,
      Sure it’s easy, disconnect the water lines, gas lines, electric lines, and the flue & air supply lines. Then take it off the wall. It could probably be done by changing all the parts that are different, but economics will say to buy the right one and install it. These Navien units can be temperamental little beasts with proper set up being key to the users satisfaction, I’d be recommending a qualified installer to anyone installing or working on one.

  4. PeteinMN says:

    I already own an NR 180 and need to convert it to NG. I have a certified gas technician friend that can convert it if possible. I suspect it is but wonder which parts need to be changed and how easy it will be for him. I also have a small insulated tank outside the unit that was added to the loop because we have rural cold well water and lower pressure than municipal supply which was a problem causing a sandwich effect.

  5. Kirk says:

    My plumber just installed a NR240 LP in my house which is currently under construction.
    He installed it in a closet located in the kitchen nook area. Are these things overly loud? I I don’t want there being a noise problem.

    • Redwood says:

      Hi Kirk,
      This would be a very typical installation location for the Navien NR240. I don’t believe you will find the operational noise of the system to be objectionable. It would probably be comparable to many of the other appliances in the home.

  6. Nanette says:

    How do you get anyone to fix one. I have spent over $500 on plumbers and it still does not work It will not keep the pilot light lit. It blows it out when trying to come on. I really wouldn’t recommend these

    • Redwood says:

      Hi Nanette,
      Why the plumber would be talking about a “Pilot Light” on a unit that has “Electronic Spark Ignition” I’m not sure, but I’d suspect you need to get a plumber that has completed factory training to service Navien products.

      What error codes are you seeing?


  7. Ray George says:

    Looking at the Navien NR-210A-NG tankless condensing water heater. What is the energy consumption when there is no usage? Does the unit keep firing to heat up the water in the little tank? How well insulated is it? Kind of defeats the purpose of getting a tankless if it runs during the night.

    • Redwood says:

      Hi Ray,
      It’s interesting to see a tankless water heater manufacturer fall victim to the advertising hype of their own industry. The reality is that the standby heat loss in an insulated tank is negligible and if you look at the Energy Guide Label you will see the NR-210-NG says $195 annual cost and the NR-210A-NG says $197. Of course if you go into an external recirculation mode then all bets are off and it depends on the insulation of the pipes in your home and the temperatures they are exposed to. I believe there is also a recirculation timer that can be set to control when the recirculation occurs so it can be set not to recirculate through the night.

      The fact remains that 1 Btu heats 1 pound of water 1 degree regardless of whether it is doing so via a large burner and tankless coil firing at 180,000 Btu/hr or, a 40,0000 Btu/hr burner under a tank. If you are looking for a drastic difference in your water heating costs to come from the elimination of standby heat loss you’ll be disappointed. The efficiency if the water heater does make a difference and the Condensing 98 is a very high efficiency unit in comparison to a standard atmospheric vented water heater, the Condensing 98 will utilize the burner heat to the point of condensing where the standard water heater will have a much higher flue temperature. However, there are also high efficiency tank type water heaters available that will attain similar efficiencies and operate in condensing mode as well.

      Tankless water heaters having a minimum flow to turn on the burner has been an annoyance for many users. Take for instance shaving, with a tank water heater I usually let the water run slowly while I shave and every once in a while turn it up higher to blast some whiskers out of the razor when the low flow doesn’t clear them all. If you do that with a tankless that doesn’t have a buffering tank you’ll find you are getting cold water out of the tap when you do that.

      I hope this helps,

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