Why heat exchanger on Noritz N 063 is leaking?

by Ronald C.

I have my tankless for seven years and it has worked very well. However it has just failed badly. It started leaking at the heat exchanger and dripped down onto the control board and killed it.

Afer replacing it with the same but new model NR71. Once removed I looked down the flu duct and I could see a lot of green crusty corrosion around the vain of the tubes inside. I have found some vague notes about produce an acid compound that can corrode the flue in searches I have done. What is about liquid propane that causes that? Can I stop it?

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Feb 28, 2015
Had To Replace Heat Exchanger After 8 1/2 yrs
by: Danny

I had an N-063S-1 (LP) water installed during new construction of my home in August 2006. A couple of months ago, I noticed that the WH wouldn't always kick on when I turned on the hot water, requiring me to go to the unit and flip the breaker for the electrical trigger, off and on. (Hindsight tells me I should have probably taken a closer look at that point.)

Yesterday I noticed water dripping down from what looked like the output valve. Closer inspection revealed the leak was actually coming from inside of the enclosure and just finding it's way "out", through the slight opening where the valve enters the unit cover.

After taking off the front cover, I could see the leak was actually coming down the copper pipe, or "heat exchanger" if you will, and dripping to the bottom of the unit enclosure. Called Noritz who verified my ser# and told me the heat exchanger had a 10-yr warranty. They shipped a new one out that same day (Friday), and it should be here Monday. Called the Noritz dealer and scheduled an install for Tuesday morning. Got an estimate of no more than 2 hrs to install at $89.50/hr.

Let me add that the water here is high in minerals and corrodes EVERTHING, even though I do have a water softener. Since I didn't do any maintenance in the 8 1/2 yrs I've had the unit, it's no surprise it's now leaking. I'm actually surprised it's lasted his long. I suspect if I flush it once a year, the new heat exchanger should last at least 10 more years or more.....hopefully. So the $200 I'm going to spend to have it installed is well worth it. It certainly isn't a DIY job.

Bottom line is that this is the first problem I've had with this unit and that Noritz customer service was unbelievably good.

Apr 22, 2013
acidic condensate
by: Phil- Express Drain & Plumbing

It's not the propane that's causing the acid. It's the condensate from the venting. I'm guessing the water heater is an indoor model and the vent is ran vertical more than 3 feet to the roof and vent cap? If so the condensate will drip back down the vent and onto the copper heat exchanger causing it to corrode, turning it green and eventually (after about 7 years in this case) leak. To prevent this the installer should have used a "condensate drip tee". Not having this will void the 10 yr warranty on that model heat exchanger. There should also be a water treatment (filter) on the cold line before it reaches the unit and water heater should be flushed every year. spend a little extra and have this done. It will protect your investment and ensure you have a warranty when/if you need it.

Apr 02, 2012
N-0751M Exchanger Leak 3 Years.
by: Fred

My heat exchanger just started leaking last week. I called one service provider and was told to call Noritz. He had said they would probably just replace the whole unit.

Installed 2/17/09. Noritz offered to send a new exchanger and call a service provider for me. After calling the Service provider and a quote for $400 + unknowns. I have decided to DIY. Question 1, Is there a step by step on this? Do you think the unit should be replace based on an early HX failure.

May 17, 2010
Troubleshooting Noritz water heaters and corrosion
by: Zee from water heater reviews

I am surprised that your Noritz tankless heater started leaking after only 7 years. They should last at least 15 years or so.

If your heat exchanger has a leak due to the bad design or crack, you should call Noritz customer service or technical support and submit a complain. Noritz provides 12 years warranty on heat exchanger and 5 years on other components.

On the other side, if the heat exchanger got frozen during the winter time and broke than Noritz will waive the warranty.

Are you sure that the leak is not from somewhere else (condensation maybe) or where it connects to the piping. Maybe the connection is loose.

Anyhow, you got a new unit and know you have a problem with corrosion in the flue duct.

I don't know what type of the flue duct did you use before, but it is recommended by code that tankless water heaters must use Category III stainless steel venting.

You can find Noritz approved venting (Category III venting) which is corrosion resistant and gas tight.

It doesn't matter do you have a Noritz water heater or any other brand, your venting MUST be corrosion resistant as the acidic condensate is formed during combustion.

Formed condensation can eat away vent pipe if it is made of other material, and cause damage to your tankless water heater's internal components.

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