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Rinnai Tankless Service, Repair & Error Codes
We install, service, and repair Rinnai tankless water heaters across the South Shore — and we can usually tell you what a code means before we even arrive.
Johnson Bros. — licensed MA master plumber, tankless specialist. Quincy & Abington offices.
Rinnai Service & Repair on the South Shore
Rinnai is one of the most widely-installed tankless brands in the country, and a solid, well-supported unit. Our flagship specialties are Navien and Viessmann, but we install, service, and repair current Rinnai models too — especially when a like-for-like swap is the cleanest path for a home that already has one.
Most Rinnai problems come down to hard water and gas supply. The South Shore's hard water builds scale in the heat exchanger, and Rinnai's LC code is the unit's early warning to descale before it turns into an overheat fault. Gas-supply and venting issues make up most of the rest. Whatever code you're seeing, start below — and see our tankless water heater page for install and conversion.
Common Rinnai Error Codes
What each code points to. Click the highlighted codes for a full breakdown of causes and fixes.
Blocked vent, dirty intake, or restricted airflow through the heat exchanger.
The burner never lit — almost always a gas-supply issue. Check the gas is fully on.
Lit but lost the flame. Gas pressure under load, a dirty flame rod, or venting.
Overheated and the fuse tripped. Usually scale restricting flow. Often a descale.
A descale reminder, not a breakdown. Handle it before it becomes a Code 14.
Output temperature too high. Related to scale and flow, like Code 14.
Condensate drainage or an inlet thermistor fault, depending on model.
The fan that moves combustion air is not running correctly.
Why Homeowners Call Us for Rinnai
We read the code before we arrive
Tell us the code and your model and we can usually triage it over the phone — so you know whether it is a quick fix or a service visit.
Descaling done right
Most Rinnai faults trace back to scale. We flush the heat exchanger properly and check the wear items while we're in there.
Licensed for the gas side
Ignition and flame-failure codes often mean gas work. We are a licensed MA master plumber — gas diagnostics and repairs are handled correctly and safely.
Upfront pricing
A $99 service fee applies toward the work, and you get a clear price before anything starts. No surprise charges.
Common Questions About Rinnai
Why South Shore homeowners choose Johnson Bros.
Rinnai acting up? Tell us the code.
Have your model number and the code on the display handy. We'll tell you whether it's an emergency, a same-day call, or a scheduled descale.
Need help fast? Call for urgent plumbing issues. Booking online is best when you want the next open appointment without waiting on the phone.
Can't talk right now? Get a callback.
How We Work
Clear communication, licensed work, and local support.
Licensed Plumbing Work
Massachusetts-licensed plumbing support backed by insured crews.
Fast Scheduling Updates
We tell you what timing is available and keep you updated if the schedule shifts.
Upfront Options
You get a clear explanation of the work and price before the job begins.
Repair-First Guidance
We help you understand whether repair, replacement, or follow-up service makes the most sense.
Rinnai acting up? Tell us the code.
Have your model number and the code on the display handy. We'll tell you whether it's an emergency, a same-day call, or a scheduled descale.
Call for urgent help now. Book online when you want the next available fit for your schedule.