Rinnai error code LC
It depends on your series. Code LC does not point at the same fault on every Rinnai unit. Find your series in the table below before you buy a part or book anyone.
What code LC means on each Rinnai series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| Non-SENSEI | Scale build-up in the heat exchanger | DIY fix | $25–$300 |
| SENSEI RX | Scale build-up lockout | DIY fix | $25–$300 |
Each series links to the full page: what the manufacturer's manual says for that generation, what you can safely check yourself, and what the repair should cost.
How much the answer changes between series
Every Rinnai series that documents code LC routes it the same way: a descale. That is unusual enough to be worth saying, because on this brand the same number often means different work on different generations. Here it does not — so you can act on this page without first establishing which unit you own.
The cost is documented the same way across all 2 series: $25–$300, depending on which of the manufacturer's causes turns out to be yours.
Which Rinnai do you have?
The model number is on the rating label on the unit itself. Match it against the list below — or use the full model-number decoder.
Where this comes from
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 67), read Aug 2026 — the manufacturer's own documentation for this Rinnai range.
Parts, guides and symptoms behind code LC
Everything the 2 Rinnai series point at for this code, in one list. A part named here is one the manufacturer's own procedure reaches for.