Navien Water Heater Service in Fresno, CA
Stedman's Plumbing is a certified Navien Service Specialist (NSS) — the highest tier of Navien-authorized contractor. That designation means our technicians have completed Navien's multi-level factory training program, covering both classroom instruction and hands-on live-fire diagnostics on current Navien units. We are listed on Navien's official NSS locator at navieninc.com, carry a stocked OEM parts kit, and have direct access to Navien's dedicated NSS technical support line. When you hire Stedman's for your Navien, you're getting a technician who knows your exact unit — not a general plumber working from a manual.
Fresno's municipal water supply is consistently rated hard to very hard, and that has direct implications for your Navien. Mineral scale accumulates on the heat exchanger over time, reducing efficiency and — if left unchecked — causing premature failure. Navien formally recommends annual descaling for units in hard water areas. Skipping this maintenance can not only reduce performance but may also affect your warranty coverage. Stedman's performs full descaling flushes per Navien's published procedure, using the correct citric acid or white vinegar solution and a fresh water rinse cycle, to keep your unit operating at peak efficiency and your warranty intact.
What It Means to Be a Navien Service Specialist
- ✓ Factory-trained through Navien's multi-level program — classroom instruction plus hands-on live-fire diagnostics
- ✓ OEM Navien parts kit kept on hand — same-day repairs without waiting on shipping
- ✓ Official NSS listing on navieninc.com — verifiable, Navien-endorsed
- ✓ Priority access to Navien's dedicated NSS technical support line for complex diagnostics
- ✓ Authorized to file and process Navien warranty claims on your behalf
- ✓ Higher warranty reimbursement rate enables faster, more thorough service
Navien Models We Install & Service
Stedman's Plumbing installs and services the full current Navien product line, including all NPE tankless units, NHW non-condensing units, NPN series, and NCB-H combi-boilers. Below are the most common models we encounter in Fresno-area homes and businesses.
NPE-A2 Series
Up to 0.95 UEF · ComfortFlow®
Navien's most popular condensing tankless unit, featuring built-in ComfortFlow® recirculation to eliminate the cold-water sandwich effect. Available in 150,000–240,000 BTU configurations for whole-home use.
NPE-S2 Series
Up to 0.96 UEF · High Output
The S2 delivers Navien's highest UEF rating and increased hot water output, ideal for larger homes with simultaneous high-demand fixtures. Condensing design recovers heat from exhaust gases for maximum efficiency.
NHW Series
Non-Condensing · Compact
A non-condensing tankless unit designed for retrofit applications where condensate drainage is not practical. Compact form factor fits tight mechanical spaces and existing venting runs.
NPN Series
NaviTech™ Stainless Exchanger
Features Navien's NaviTech™ stainless steel heat exchanger, engineered for superior corrosion resistance and longevity. Well-suited for commercial applications and high-demand residential use.
NCB-H Combi-Boilers
Up to 150,000 BTU · Heat + DHW
Navien's combination boiler provides both space heating and domestic hot water from a single wall-hung unit. Ideal for homes with hydronic radiant floor heating. We install and service the full NCB-H line.
Common Navien Problems We Fix
Navien units display error codes to help diagnose issues — and our NSS-trained technicians know exactly what each code means and what parts are needed. Below are the most common Navien problems we repair in Fresno.
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E003 — Ignition Failure
The unit attempted to ignite but failed to establish a flame. Common causes: insufficient gas supply or pressure, faulty flame rod, dirty or blocked burner assembly, or venting restriction preventing proper air intake or exhaust. Always requires a certified technician.
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E004 — False Flame / Heat Exchanger
The control board has detected flame when it shouldn't exist, or a heat exchanger fault is present. This code always requires a certified Navien technician — do not attempt to reset and operate the unit until inspected.
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E351 — Flow Sensor Error
The flow sensor is reading incorrectly, often due to a clogged inlet filter screen or scale buildup restricting water flow. A common issue in Fresno's hard water. Cleaning the inlet filter and descaling typically resolves this code.
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E012 — Flame Loss
The unit established a flame but lost it during operation. Causes include fluctuating gas pressure, a dirty or blocked air filter restricting combustion air, or venting issues. Gas supply should always be checked first.
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Heat Exchanger Descaling
Fresno's hard water deposits calcium and magnesium scale on the heat exchanger over time. Annual descaling is Navien's formal recommendation — and skipping it in Fresno's water conditions significantly accelerates scale accumulation and heat exchanger degradation.
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Recirculation Pump Issues
ComfortFlow®-equipped NPE-A2 models use an internal recirculation pump that can develop noise, intermittent operation, or failure over time. We stock common Navien recirculation pump components and can typically complete this repair same-day.
Fresno Hard Water & Your Navien
Fresno's municipal water supply consistently measures in the hard to very hard range — typically 200–300 mg/L (parts per million) of dissolved calcium and magnesium. Every gallon of hot water your Navien heats deposits a small amount of that mineral content inside the heat exchanger. Over months, this scale layer thickens, reducing heat transfer efficiency, increasing gas consumption, and putting additional thermal stress on the unit's stainless steel components.
Navien formally recommends annual descaling for units operating in hard water areas. Stedman's Plumbing performs the full Navien-specified descaling procedure: connecting a descaling pump and solution reservoir to the unit's service ports, circulating citric acid solution through the heat exchanger, followed by a complete fresh water flush and rinse. The entire service typically takes under two hours and leaves your unit performing like new. Beyond performance, annual descaling is important for warranty compliance — Navien can deny heat exchanger warranty claims on units with documented neglect of the recommended maintenance schedule. Don't risk a costly heat exchanger replacement: schedule your annual descale with Stedman's.
Our Navien Service Process
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Call or Schedule Online
Call 559-770-9772 or request an appointment online. Describe your Navien issue — including any error codes displayed — so we can prepare for the visit. Same-day availability in most cases.
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On-Site Diagnosis with Error Code Reading
Our NSS technician reads the unit's error history, checks gas pressure and flow rate, inspects the inlet filter, venting, and flame rod, and performs a full diagnostic to identify the root cause — not just clear the code.
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Flat-Rate Quote — No Surprises
We provide a flat-rate repair quote before any work begins. You know the full cost upfront. No hourly billing, no add-on charges once we start. You approve the repair or we walk away — no pressure.
4
Repair or Installation with OEM Navien Parts
We use only OEM Navien parts — never generic substitutes. As an NSS contractor, we stock the most common Navien components, enabling same-day repairs without waiting for shipping. Warranty replacements are handled directly with Navien.
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Test, Verify & Walk-Through Before We Leave
After every repair or installation, we run the unit through multiple heat cycles, verify the outlet temperature, check for error codes, and confirm hot water delivery at your fixtures. We walk you through the work completed and answer any questions before departing.
Service Area: Serving Fresno, Clovis, Madera, Sanger, Reedley, and the Central Valley.
Frequently Asked Questions
What is a Navien Service Specialist?
A Navien Service Specialist (NSS) is a plumbing company that has completed Navien's factory training program — a multi-level curriculum covering classroom instruction and hands-on live-fire diagnostics. NSS contractors are listed on navieninc.com's official locator, carry OEM Navien parts, have access to Navien's dedicated NSS tech support line, and are authorized to file and process Navien warranty claims on your behalf. Stedman's Plumbing is a certified NSS serving Fresno and the Central Valley.
Do you service Navien combi-boilers?
Yes. Stedman's Plumbing services all Navien NCB-H combi-boilers, which provide both space heating and domestic hot water from a single wall-hung unit. Our technicians are trained on the full Navien product line, including combi units up to 150,000 BTU. Whether your NCB-H is showing an error code, has reduced heating output, or needs annual maintenance, we can help.
My Navien shows error code E003 — what does that mean?
Error code E003 on a Navien unit indicates an ignition failure — the unit attempted to ignite but failed to establish a flame. Common causes include insufficient gas supply or pressure, a faulty flame rod, a dirty or blocked burner assembly, or a venting restriction preventing proper air intake or exhaust. Do not attempt to reset and run the unit repeatedly — call Stedman's at 559-770-9772. Our technicians can often narrow down the cause over the phone and arrive prepared with the right parts.
How often should I have my Navien descaled in Fresno?
Navien recommends annual descaling for units in hard water areas, and Fresno's municipal water supply is consistently rated hard to very hard. Annual flushing with a citric acid solution removes mineral scale from the heat exchanger, maintains efficiency, and — critically — keeps your Navien warranty valid. Skipping annual maintenance in Fresno's water conditions can lead to premature heat exchanger failure and potential warranty denial. Stedman's performs full descaling per Navien's published procedure.
Does using a non-certified plumber void my Navien warranty?
Navien's warranty requires that service be performed by a qualified technician. Work performed by an uncertified plumber who lacks Navien-specific training — especially for warranty claims or repairs — can be grounds for claim denial. A non-NSS plumber also cannot access Navien's dedicated tech support line or file warranty claims directly. Using a Navien Service Specialist like Stedman's ensures all repairs meet Navien's standards and that valid warranty claims can be filed and processed on your behalf.
