Noritz NRCP Eco TOUGH Code Er20
High limit switch fault. The high limit switch has tripped. Noritz gives the same sequence as Er16 on this generation — thirty minutes off before restarting, then the cold water inlet and recirculation return filters, then a flush of the heat exchanger. Unlike Er16 this one is a manual reset: the unit will not clear it by itself.
Also displayed as: 20, E20
DIY fixThe verdict
Descale the unit
The same three actions as Er16 and the same order, but you have to reset it yourself. What matters is not to keep resetting past it: a high limit switch that trips repeatedly with clean filters and a flushed exchanger is telling you something else is wrong.
Typical cost: $0–$500
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
- Turn the water heater off for at least thirty minutes before restarting it.
- Clean the cold water inlet filter and the recirculation return filter.
- Flush the heat exchanger.
- If it trips again after all three, stop resetting and book a service call. Never bypass or jumper a high limit switch.
Code Er20 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:
Don't confuse this with
3 other Noritz NRCP Eco TOUGH codes point at a switch too. They are different components in different places, and ordering a part against the wrong one is the most common way this fault gets expensive: