Noritz tankless water heater code Er78
Quick Connect communication error. Code Er78 means the same thing on all 2 Noritz series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code Er78 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| NRCP | Quick Connect communication error | Part replacement | $0–$400 |
| NRCP Eco TOUGH | Quick Connect communication error | Part replacement | $0–$400 |
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 Er78 — 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 Er78 agree and where they part company.
NRCP — Quick Connect communication error
Two or more of these heaters are linked as a Quick Connect system and have lost communication. Noritz's remedies are to check the QC-NRCP-1 cable connection and to check the Quick Connect setting on both units — both of them, not just the one showing the code.
NRCP Eco TOUGH — Quick Connect communication error
Two or more of these heaters are linked as a Quick Connect system and have lost communication. Noritz's remedy is to check the Quick Connect communication cable. Auto reset.
Does it matter which Noritz you have?
NRCP and NRCP Eco TOUGH all route code Er78 the same way: a replacement part, at $0–$400. 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 Er78, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- If it stays, book a service call.
That is 1 of the 3 checks documented for code Er78. 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 Er78, 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 Er78
Code Er78 on these 2 Noritz series points at 2 parts and 2 symptoms, each named by the manufacturer's own procedure for this code.