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
The same code number can mean something different on another series — make sure you're reading the page for your exact unit: