Noritz NRCP Eco TOUGH 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 remedy is to check the Quick Connect communication cable. Auto reset.
Also displayed as: 78, E78
Part replacementThe verdict
Replace a part
One named cable. Nothing is wrong with either heater's ability to heat water — they have lost the link that coordinates them, which shows up as a shortfall in 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 Eco TOUGH — not averaged across the brand.
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 exact series.
What you can safely check
- Check the Quick Connect communication cable is seated at both ends and undamaged.
- Cycle the power on both units.
- 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 Eco TOUGH 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: