Complaint: No Hot water - Noritz NR C98DV Tankless Water Heater - Code 51 on Display Remote
Model NRC98DV... NR: Stands for Noritz Residential, C: Indicates Condensing unit (use a second heat exchanger to extract heat from exhaust gases), 98: maximum flow rate, 9.8 gallons per minute (GPM), DV: Direct Vent, uses a sealed venting system to draw air from outside for combustion
Let's get started... There is no hot water from my Noritz NRC98DV
tankless water heater and is displaying Error Code 51 – which indicates gas
manifold solenoid failure. This code is activated when there is insufficient
gas flow and the unit shuts down.
Failures from Error Code 51 ranges from poor gas valve
connection to a defective solenoid valve. Upon inspection and testing, water
leaked into the gas manifold and caused the solenoid to malfunction.
What
caused this problem? The problem was caused by a leaky heat
exchanger. The heat exchanger in a tankless water heater is where cold water
passes over superheated coils to quickly deliver hot water to the faucet.
When a tankless water heater is not descaled regularly, hard water
causes mineral buildup (scale) and corrosion. This can lead to overheating and
cracking of the heat exchanger.
A small pinhole or crack in the heat exchanger
can cause water to drip onto the gas manifold, control board, fan and other
electronics.
Note: Water damaged parts included in the 12 years warranty from Noritz included (see YouTube video below):
- Heat exchanger
- Gas manifold (technician must verify watermarks in and around the gas manifold plate for warranty)
- Heat exchanger fan assembly
- Additional installation wires and mounting screws
Leaking
Heat Exchanger Replacement of a Noritz NR98OD Tankless Water Heater by Dennis The Plumber - https://www.youtube.com/watch?v=PlpaO2k4Vec
Heat Exchanger Parts List - https://support.noritz.com/tankless-water-heaters-residential-nrc-series-nrc98-dv-ng
Noritz Service Repair Manual (Free Download) - https://support.noritz.app/technical-literature?selected_model=NRC98-DV-NG
How to Replace the Gas Manifold - Replacing the Manifold and Checking Gas Pressures by noritzamerica - https://www.youtube.com/watch?v=ZdGgWOBalE0
What’s
the Real Cause of this Failure? The real cause is lack
of maintenance or neglecting to descale the tankless water heater on a yearly
basis.
Would
you believe I operated this unit for 8 years - totally unaware of any maintenance requirements? Likewise, how many other homeowners neglect critical maintenance requirements for their units? It's way too many!
The purpose of this blog is to help you save money by learning how to maintain your own unit.
Scheduled Maintenance Requirements - Noritz NRC98DV:
Periodic maintenance can prevent water damage failures and ensure many years of trouble-free operation. Noritz recommends:
1. Annual Inspection: Check the cold water inlet filter for debris; inspect the front cover, fan, and venting for dust and debris.
2. Heat Exchanger Flush: Flush the heat exchanger to remove scale buildup - especially if you have hard water.
3. Professional Servicing: Hire a professional to maintain and inspect unit yearly
How
to Pull Error Codes from Noritz Tankless Water Heater?
Noritz provides a walk-through video for homeowners
demonstrating the process of pulling codes from the handheld display…
Checking the Error Code History :
Noritz Tech Tip by noritzamerica - https://www.youtube.com/watch?v=zqqJT907sRI
Huge List of Noritz Error Codes - https://help.noritz.com/index.php/article-tags/errorcodes/
Here’s
the step-by-step procedure for retrieving error codes on a Noritz NRC98DV using
the residential remote:
1.
Turn Off the Remote: Press the Power button to turn the
remote off.
2.
Enter Diagnostic Mode: Hold down both the Up and Down
arrow buttons simultaneously until 03 is displayed.
3.
Access Error Code History: Press the Down button once to enter
the error code history.
4.
View Stored Error Codes: Press the Up button to scroll
through the error codes, one by one.
5.
Identify the End of Error Codes: Continue scrolling through the error code history
until you see 000. This indicates the end of the recorded
error codes.
6.
Exit Diagnostic Mode: Hold down both the Up and Down
arrow buttons simultaneously to exit.
7.
Turn the Remote Back On: Press the Power button to turn the
remote back on.
A listing of procedures can be found inside the
unit, behind the cover panel once it is removed under “Displaying
Maintenance Monitors.”
What
are the terms of Noritz NRC98-DV-NG
tankless water heater warranty?
Heat Exchanger:
·
Without Recirculation: 12 years
·
With Recirculation: 12 years
Parts: 5 years
Labor: 1 year
The
warranty terms are detailed on Noritz's support page for NRC98-DV-NG… https://noritz.com/warranty
Noritz's EZ Series models
come with a 25-year warranty on the heat exchanger when installed in
single-family homes.
How Much is Labor Costs and Parts?
Several technicians estimated 5-6 hours of labor at an approx. cost of $3,000. This rate is
significantly higher than standard rates for appliance
repair (ranging $500 to $600 per hour as compared to $100 to $200 per hour).
Tankless water heaters
are safe, energy efficiency, provides an endless amount of hot water, and have a long lifespan, however they require strict maintenance to ensure their longevity.
Possible replacement parts cost for water
damaged units:
1.
Gas Manifold Assembly:
Controls the distribution of gas to the burners - $200 - $300
2.
Control Board:
Manages the operation of heater, including temperature control and
safety functions - $150 - $250
3.
Water Flow Sensor with Thermistor:
Detects and monitors water flow to control heating and water temperature $100 - $150
4.
Transformer: Provides power to control board and electrical devices $80 - $120
5.
Wiring Harness:
Connects electrical components inside the unit - $30 - $50
6.
Water Filter Cover with Inlet Filter: Filter debris from entering the unit - $20
Save Money with Federal and State RebatesIn 2025, homeowners who install energy-efficient tankless water heaters may
be eligible for federal tax credits and state rebates through...
- Energy Efficient Home Improvement Credit: homeowners claim 30% of the cost of qualifying
energy-efficient improvements on certain tankless water heaters, up to
a maximum of $600 annually irs.gov
- Federal Tax Credit: The Energy Efficient Home Improvement Credit is available to homeowners in every state - including eligible upgrades to certain high‑efficiency tankless water heaters. Get a complete listing of resources at DSIRE - Database of State Incentives for Renewables & Efficiency (enter your zip code and find savings in your state)
- Arkansas Oklahoma Gas (AOG): Provides a $700 rebate for installing natural gas tankless water heaters with a Uniform Energy Factor (UEF) of 0.90 or higher aogc.com
- State Rebates in Arkansas available through Black Hills Energy Arkansas: Offers rebates on qualified water heating equipment (see eligibility requirement) at Residential Energy Efficiency Rebates
Not Affiliated with Noritz or Any Publisher in this Blog
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