Noritz tankless water heater code Er65
Your series decides which reading applies. Across the 2 Noritz series documented here, code Er65 is listed as water control valve fault (1 series) and water adjustment valve fault (1 series). Find your series in the table below, where those readings route to a replacement part.
What code Er65 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| NRCP | Water control valve fault | Part replacement | $200–$700 |
| NRCP Eco TOUGH | Water adjustment valve fault | Part replacement | $200–$700 |
Each row opens the full page for that generation. We hold manuals for NRCP and NRCP Eco TOUGH, and each one gets its own reading of code Er65 — what Noritz documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 2 series in four columns, which is enough to route you and not enough to explain anything. This is the Noritz wording behind each row, one entry per manual, so you can see where the 2 readings of code Er65 agree and where they part company.
NRCP — Water control valve fault
The water control valve is not behaving. Noritz's remedy is one line — check the water control valve. This is the motorised valve that meters flow through the heat exchanger, and it is how the unit holds a set temperature as demand changes.
NRCP Eco TOUGH — Water adjustment valve fault
The water adjustment valve is not behaving. Noritz's remedy is one line — check the water adjustment valve. This is the motorised valve that meters flow through the heat exchanger; the first-generation manual calls the same part the water control valve. Manual reset.
Does it matter which Noritz you have?
NRCP and NRCP Eco TOUGH all route code Er65 the same way: a replacement part, at $200–$700. That makes it one of the Noritz numbers you can act on before working out which unit you own.
What to check first, whatever your series
These checks are on the manufacturer's list for every Noritz series that reports code Er65, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- Note what the water is actually doing — too hot, too cold, or swinging — and tell the technician.
- Book a service call.
That is 2 of the 2 checks documented for code Er65. The rest differ by generation, so if none of those explains it, go to your own series above.
Which Noritz do you have?
On the 2 series that report code Er65, the model number on the rating label starts NRCP — match yours against the 4 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Noritz Service Manual — NRCP111-DV / NRCP98-DV (Rev. 09/19) (p. 62), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Source: Noritz Service Manual — NRCP1112-DV / NRCP982-DV Eco TOUGH (Rev. 05/19) (p. 58), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Parts, guides and symptoms behind code Er65
Code Er65 on these 2 Noritz series points at 2 parts and 2 symptoms, each named by the manufacturer's own procedure for this code.