Noritz NR98 & NR111 Code 65
Main flow control valve fault. The main flow control valve is not functioning. Noritz checks that the valve works and looks for an improper connection, and notes that the power has to be cycled to clear the code. This is the motorised valve that meters how much water goes through the heat exchanger. This table pairs the main and bypass flow control valves at 65 and 66 and stops there. The NRCP ranges add a mixing valve on top of both; the EZ and NCC199CDV call the same two parts water servos. Same job, three different names across one manufacturer.
Also displayed as: F65
Part replacementThe verdict
Replace a part
Cycle the power first — Noritz's own reset, and a valve that stuck once may free itself. If it returns it is the valve or its wiring, which is a service call and a moderately priced part.
Typical cost: $0–$700
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 NR98 & NR111 — not averaged across the brand.
Source: Noritz Service Manual — NR50 / NR66 / NR71 / NR98 / NCC199 / NRC111 / NR111 / NC380 (Rev. July 2011) (p. 56), read Sep 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
- Switch off at the breaker, wait a minute, switch back on.
- Run a hot tap and see whether the code returns.
- If it returns, book a service call.
Code 65 on other Noritz series
The same code number can mean something different on another series — make sure you're reading the page for your exact unit:
Don't confuse this with
3 other Noritz NR98 & NR111 codes point at a valve too. They are different components in different places, and ordering a part against the wrong one is the most common way this fault gets expensive: