A leak near the bottom left corner of a Navien NR-210 can worry any homeowner.
That area is close to the heat exchanger and nearby water connections.
So, it is easy to think the whole heat exchanger has failed.
That may be true, but it is not always the first answer.
Water can travel inside the cabinet before it drips out.
A leak may start at a fitting, gasket, O-ring, pipe, or valve.
Then it may show up near the heat exchanger corner.
This is why the cover must be removed for a close check.
Turn off power, gas, and water before any inspection.
Gas appliances can be dangerous when opened or serviced.
A licensed plumber should inspect the unit if you are unsure.
You can also review Navien’s official NR and NP series manuals.
Question
I have a leak from the bottom left corner of my Navien NR-210 heat exchanger.
Does this mean the whole heat exchanger assembly must be replaced?
Also, will an NR-210A heat exchanger fit an NR-210 without the pump?
Answer
Not always. A leak there may mean the heat exchanger has failed. But it could also be a nearby seal, pipe, or fitting. If the leak is from the sealed heat exchanger body, the heat exchanger assembly usually needs replacement.
Do not assume the NR-210A part fits the NR-210. The “A” model includes internal recirculation parts. Always match the part by full model, gas type, and serial number.
What To Check First
Look for staining above the leak point.
Check for water trails on pipes and fittings.
Check the cold and hot water connections.
Look around the condensate area and drain lines.
Also inspect O-rings and union fittings.
If the exchanger itself is cracked, repair is not simple.
Most contractors replace the full heat exchanger assembly.
That repair can be costly on an older unit.
Ask for a written price before approving the job.
Compare that cost with a new tankless heater.
How To Confirm The Right Part
Use the rating plate on the side of the heater.
Write down the full model number.
Also, write down the serial number.
Then contact Navien technical support.
You can also compare parts with a trusted supplier.
For example, some suppliers list separate Navien parts by model.
Still, the safest match comes from Navien or a licensed dealer.
Final Plumbing Tip
Do not keep running the heater with an active leak.
Water can damage wiring, sensors, and the control board.
That can turn one repair into many repairs.
Shut the unit down and get it checked soon.
I’m Chris Mayer, writing for Plumbing 101.
