Happy with Noritz N-0751M-OD, BUT...
by Michael Lawler
(Los Angeles CA)
We have a model N-0751M-OD, (mounted outdoors). After about three years it started throwing a trouble code 90. A call to customer service yielded a very thorough diagnostic walk-through ending in a diagnosis of the fan needing cleaning. Since it wasn't coding often and wasn't too big a problem, I ignored it for a while until it started throwing code 14.
After Googling and another call to customer service: this time it was the Thermal Fuse Wire (a $9 part). Ok, time to fix it. Noritz has excellent illustrated service step-by-step instructional PDFs available to download online, which is a good thing.
My beefs: when I removed the fan, it was barely dirty at all. If this minuscule dirt load (on a heater designed for outdoor mounting) caused enough overheating to blow the thermal fuse wire, then I would suggest that this fan is SERIOUSLY UNDER-SPEC'D for its intended job.
It's really quite absurd to have to disassemble the heater to clean this fan on a three year interval to remove what should be an acceptable amount of dirt. (Also, please note there is no air filter in this system -- a part which could lengthen the service interval and be easily replaced.)
Also note -- my opinion here -- that if fan cleaning is a regular maintenance issue, NORITZ SHOULD DESIGN THE HEATER FOR AN EASY, FOUR-SCREW FAN REMOVAL, not the disassemble-the-whole-damn-unit job that it is.
My same gripe applies to replacing the thermal fuse wire. Easy maintenance access was not an issue even considered by Noritz's designers. A simple access plate would have made this an easy replacement. As it is, get ready to take the entire unit apart. Let me put it this way: It's not horrible to disassemble the unit because the instructional PDFs are quite clear and all the wiring (of which there is a WHOLE lot) is put together with different size plugs, making mis-reassembly more or less impossible.
BUT -- I don't think this sort high-maintenance short-interval servicing is acceptable for a unit that cost over a grand. And I'm pretty handy and can do this stuff, but I doubt many homeowners would want to dive into these tasks.
So add a couple of $300-plus service calls to the $1000-plus unit in the first five years and you've got quite an expensive and troublesome alternative to a carefree tank-style water heater (which also works, I might add, when the electricity goes off).
Add to the unscheduled troubles the fact that you have to descale the unit annually, and you're in for either a yearly chore or an annual service call from your friendly plumber. The descaling I can put up with; the early failures, not so much. It's great when it's working, but in my opinion its key systems are under-designed and not spec'd for long, trouble free service.