Noritz NRCP Code Er20
Water high limit switch fault. The water high limit switch has tripped. Noritz gives the same three remedies as for Er16 — power off and on, clean the cold water inlet and recirculation return filters, flush the heat exchanger — which says plainly what the manufacturer thinks trips this switch on a recirculating unit: not enough water moving through a firing heat exchanger.
Also displayed as: 20, E20
DIY fixThe verdict
Descale the unit
Same three actions as Er16, and the same order. What matters is not to keep resetting past it: the switch is a safety device, and if it trips again after the filters are clean and the heat exchanger is flushed, something else is genuinely overheating.
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 — 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
- Cut the power for a minute and restore 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.
Frequently asked questions
Other Noritz code lists say a high limit fault is a professional job. Why does this page start with filters?
Because this manual does. On the NRC series Noritz gives only switch and connection checks for its code 20, so that page sends you to a technician. On the NRCP the manufacturer's own remedies are two filters and a flush. Same brand, different range, different instruction — which is why we file them separately.
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 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: