Noritz NRCP Code Er78
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.
Also displayed as: 78, E78
Part replacementThe verdict
Replace a part
One named cable and a setting on each unit. Nothing is wrong with either heater's ability to heat water; they have lost the link that coordinates them, which shows up as capacity rather than as a breakdown.
Typical cost: $0–$400
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 NRCP — not averaged across the brand.
Source: Noritz Service Manual — NRCP111-DV / NRCP98-DV (Rev. 09/19) (p. 62), read Sep 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
- Check the QC-NRCP-1 cable is seated at both ends and undamaged.
- Check the Quick Connect setting on both units, not only the one displaying the code.
- If it stays, book a service call.
Code Er78 on other Noritz series
Other Noritz series report code Er78 under the same fault name, but each manual is transcribed separately and they do not read alike:
Don't confuse this with
One other Noritz NRCP code points at a link between two boards too. They are the same symptom reported from a different place in the unit, so which one the display shows is what tells you where to look: