Rinnai Tankless Water Heater Repair in Sacramento, CA

What do Rinnai error codes mean?

A Rinnai tankless unit checks its own operation and flashes a code on the temperature controller. Rinnai's VB Series manual says the code may help you solve a problem without a service call, but some checks must be done by a qualified service technician, and a technician should handle any remedy that involves gas or electricity.

Rinnai also publishes a separate diagnostic code guide for its SENSEI and non-SENSEI series, with troubleshooting steps for each code. Use the manual for your model, since the lists vary by series.

What does the Rinnai LC code mean?

LC means scale is building up in the heat exchanger. Rinnai says the unit is beginning to lime up and must be flushed, and that failing to flush it will damage the heat exchanger. The LC code is the only one that allows the unit to keep running. The display alternates between LC and the temperature setting and the controller keeps beeping.

Rinnai's diagnostic guide says newer non-SENSEI models lock out after repeated LC warnings if the unit is not flushed. SENSEI models have a time-based service indicator, SS, set during installation to 0.5, 1 or 2 years, that tells the owner it is time to flush.

How do you flush a Rinnai tankless heat exchanger?

Rinnai's manual calls for 4 gallons of undiluted, food-grade white vinegar. The steps are to cut power, close the hot and cold shutoff valves, connect a pump to the service valves and circulate the vinegar through the unit for at least 1 hour at 4 gallons per minute. Then rinse with clean water for 5 minutes, remove and clean the cold water inlet filter and restore power. The manual also says to clean the thermistors with a soft cloth after removing the O-rings.

The procedure needs service valves, a pump and hoses. A plumber can add service valves if the unit lacks them. Rinnai says damage from lime build-up is not covered by the warranty, so keep a record of each flush.

Is Sacramento water too hard for a Rinnai?

Rinnai's manual lists a water quality target of total hardness up to 200 mg/L. If your water exceeds the target, it suggests treating or conditioning the water. Many Sacramento-area customers are under that number: Folsom Lake supplies run about 10 to 33 mg/L, and the City of Sacramento's system averages 83.

Some are not. Sacramento Suburban Water District reports wells from 51 to 280 mg/L in its South Service Area, Roseville's wells reach 280, Elk Grove Water District reports 62 to 240, Golden State Water's Cordova system reports 25 to 270 and the City of Davis reports 61 to 510. Individual wells are blended before water reaches your tap, so check your supplier's report.

What does the Rinnai warranty cover?

In the VB Series manual, residential coverage is 12 years on the heat exchanger, 5 years on all other parts and components, and reasonable labor for 1 year. Coverage runs from the date of purchase. It drops to 3 years if the unit is used as a circulating water heater in a loop without on-demand recirculation. Space heating-only closed-loop applications have no coverage.

Rinnai says to use a state-qualified or licensed installer and that improper installation may void the warranty. Repairs must be done by a properly trained, state-qualified or licensed servicer using genuine Rinnai parts. Proof of purchase is needed, either a dated sales receipt or registration within 30 days. Terms differ by model and version, so check yours.

How much does Rinnai repair cost?

No source gives Rinnai-specific prices. HomeGuide puts professional tankless maintenance at $75 to $300 nationally, and general water heater repairs run $150 to $750 (Fixr, 2025). Ask for a written estimate and tell the plumber the code you saw.

How do I check the license of a plumber who works on Rinnai units?

Ask for the contractor license number and look it up on the CSLB website. Permitted water heater work requires a licensed contractor, and the plumbing classification is C-36. Calls are answered by independent local plumbers who work on Rinnai units and does not do the repair itself. Call (916) 712-7030 to talk to a local water heater plumber.

Frequently asked questions

Available across the Sacramento area

• Sacramento
• Elk Grove
• Roseville
• Folsom
• Citrus Heights
• Rancho Cordova
• Rocklin
• Lincoln
• Davis
• West Sacramento
• Woodland
• El Dorado Hills
• Carmichael
• Fair Oaks
• Orangevale
• Arden-Arcade
• Antelope
• North Highlands
• Granite Bay
• Gold River
• Rio Linda
• Galt
• Auburn
• Cameron Park
• Placerville
• Loomis