Rinnai RH180 Hybrid Code 13
Combustion fault. Rinnai's remedy for code 13 on the RH180 is one line — review the items listed under codes 05 and 10 — which tells you exactly what it is: the appliance has decided combustion is not right, and the two candidate causes are a restricted air screen and a restricted vent or air supply. The manual's air screen section confirms it, naming 13 alongside 05 as a symptom of a dirty screen, and then draws the line clearly: if 13 is still flashing after the screen is clean, turn the unit off and get a qualified service provider.
Call a proThe verdict
Call a licensed plumber
Clean the air screen first — Rinnai names it as a cause and it costs nothing. But unlike code 05, this one has a hard stop attached: if 13 comes back with a clean screen, Rinnai tells you to shut the unit off rather than keep running it, because the remaining cause is the vent and combustion side.
Typical cost: $0–$900
US estimate for parts and labor. Prices vary by region and by who does the work — see how we estimate costs.
What the manual says
The meaning above is transcribed from the manufacturer's diagnostic documentation for the RH180 Hybrid — not averaged across the brand.
Source: Rinnai RH180 Operation and Installation Manual (100000319) (p. 35), read Sep 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- Power the unit off at the controller and clean the air screen the way the manual describes for code 05.
- Check the vent terminal outside is clear while you are at it.
- Power back on and watch the display.
- If 13 returns after a clean screen, turn the unit off and contact a qualified service provider — that is Rinnai's own instruction, not a suggestion.
Frequently asked questions
Why does a dirty filter show as 05 sometimes and 13 other times?
Rinnai's maintenance section names both. The practical difference is in what the manual tells you to do when cleaning does not fix it: on 05 you are sent to the code 10 checks, on 13 you are told to turn the unit off and call someone. Treat 13 as the more serious of the two.