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Johnson Bros. Plumbing & Drain Cleaning

Navien Service, Repair & Annual Maintenance

Error code on the front panel? No hot water on a Saturday morning? Original installer ghosted you? We diagnose the root cause, fix what is actually broken, and get you on a real annual service schedule.

Johnson Bros. — Quincy & Abington offices. $99 to send a licensed technician out, not charged at all if you approve the repair.

Call (617) 479-9911Book Online
MA Master Plumber Lic. PL #17034-M · Corp. #458124/7 emergency line4.8 stars · 385 Google reviewsQuincy & Abington offices

What a Real Navien Service Visit Covers

Heat exchanger descale (flush)

Pump cleaning solution through the heat exchanger for 45–60 minutes. Scale is the #1 killer of tankless units. Annual descaling is the most important service task.

Inlet water filter cleaning

Remove, inspect, rinse. Grit collects here and restricts flow if ignored.

Flame rod inspection

Flame rod fouling causes ignition codes (E003, E004). We clean or replace if needed.

Combustion analysis

We verify CO and O2 are within spec. This is how you know combustion is actually correct, not just that the unit fires.

Condensate trap & drain check

Blocked condensate trips lockouts. We clean the trap and verify the neutralizer media.

Error log review

We pull the Navien error log and look at what the unit has been telling you even if you missed it.

Common Navien Error Codes We Handle

E003
Ignition failure

The most common startup fault. Gas valve, flame rod, venting, or low gas pressure.

E012
Flame loss during operation

The unit lit and then lost the flame. Flame rod, gas pressure, or combustion air.

E016
Heat exchanger overheating

Scale or low water flow pushes the exchanger past its safe temperature. Usually a descale.

E027
Outlet water temperature sensor

A sensor or wiring fault. Straightforward diagnostic and part replacement.

E030
Exhaust overheating

Flue temperature over its safe limit, usually the same scale and flow problem behind E016.

E048
Gas pressure fault

Abnormal gas pressure, common on propane with a low tank or a failing regulator. Licensed diagnosis.

Common Questions About Navien Service

My Navien is throwing an error code — can you service it?
Yes. We service all current Navien residential models — NPE tankless water heaters and NCB/NFB combi boilers. Call (617) 479-9911, tell us the model (it's on the side label) and the code, and we'll tell you whether it's something to treat as emergency or standard diagnostic.
How often does a Navien need maintenance?
Every 12 months. That visit includes flushing and descaling the heat exchanger, cleaning the inlet water filter, inspecting the flame rod and condensate trap, and verifying combustion is in spec. In hard-water areas of the South Shore, descaling may be needed more often.
What happens if I skip annual service?
Scale buildup in the heat exchanger is the #1 reason tankless units fail early. Skipped service leads to reduced flow, error codes, short-cycling, and in the worst case, a ruined heat exchanger — which is close to the cost of replacing the whole unit. Annual service is cheap insurance.
Can you take over service on a Navien the original installer no longer supports?
Yes. We do take-over service on existing Navien units. We start with a diagnostic and combustion check, identify any install issues (wrong venting, undersized gas, missing flush valves), and get you on an annual maintenance schedule. If the original installer cut corners, we document what we find and fix it properly.
Are parts in stock locally?
Most common Navien service parts (flame rods, ignition components, sensors, PC boards, pump assemblies) are available through local parts channels on the South Shore. We carry the fast-moving items on our trucks. For rarer parts we get next-day or two-day delivery.
Local trust + next step

Why South Shore homeowners choose Johnson Bros.

Family-owned and local
Serving Quincy, Abington, and the South Shore.
Licensed and insured
MA Master Plumber License PL #17034-M with insured work and professional standards.
Clear service path
We'll review your request and confirm the next available appointment.

Need Navien service or diagnostics?

Call if it's down or throwing a code so we can triage the visit. If you're setting up annual maintenance, book and we will put you on the schedule.

Book OnlineCall (617) 479-9911
Not sure what's wrong? Send a photo or video

Booking online is the quickest way to hold the next open appointment. Call instead if it is urgent and you would rather talk to someone.

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Areas we serve
QuincyAbingtonBostonBraintreeWeymouthMiltonRandolphHingham

Related services

Navien Overview

Main Navien specialty page.

Navien Installation

Installing a new Navien — proper gas, venting, commissioning.

Navien Error Codes

Complete guide to common Navien fault codes.

How We Work

Clear communication, licensed work, and local support.

Licensed Plumbing Work

Massachusetts-licensed plumbing support backed by insured crews.

Local, professional service

Fast Scheduling Updates

We tell you what timing is available and keep you updated if the schedule shifts.

Clear communication

Upfront Options

You get a clear explanation of the work and price before the job begins.

No surprise starts

Repair-First Guidance

We help you understand whether repair, replacement, or follow-up service makes the most sense.

Straight answers
Licensed & Insured
Family-Owned Since 2008
Local Coverage
Plumbing Specialists
Clear Options
Emergency Line

Need Navien service or diagnostics?

Call if it's down or throwing a code so we can triage the visit. If you're setting up annual maintenance, book and we will put you on the schedule.

Call (617) 479-9911Book Online

Call for urgent help now. Book online when you want the next available fit for your schedule.