Noritz tankless water heater code Er20
Your series decides which reading applies. Across the 2 Noritz series documented here, code Er20 is listed as water high limit switch fault (1 series) and high limit switch fault (1 series). Find your series in the table below, where those readings route to a descale.
What code Er20 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| NRCP | Water high limit switch fault | DIY fix | $0–$500 |
| NRCP Eco TOUGH | High limit switch fault | DIY fix | $0–$500 |
Each row opens the full page for that generation. We hold manuals for NRCP and NRCP Eco TOUGH, and each one gets its own reading of code Er20 — what Noritz documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 2 series in four columns, which is enough to route you and not enough to explain anything. This is the Noritz wording behind each row, one entry per manual, so you can see where the 2 readings of code Er20 agree and where they part company.
NRCP — 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.
NRCP Eco TOUGH — 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.
Does it matter which Noritz you have?
NRCP and NRCP Eco TOUGH all route code Er20 the same way: a descale, at $0–$500. That makes it one of the Noritz numbers you can act on before working out which unit you own.
What to check first, whatever your series
These checks are on the manufacturer's list for every Noritz series that reports code Er20, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- 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.
That is 3 of the 4 checks documented for code Er20. The rest differ by generation, so if none of those explains it, go to your own series above.
Which Noritz do you have?
On the 2 series that report code Er20, the model number on the rating label starts NRCP — match yours against the 4 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Noritz Service Manual — NRCP111-DV / NRCP98-DV (Rev. 09/19) (p. 62), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
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 Noritz range.
Parts, guides and symptoms behind code Er20
Code Er20 on these 2 Noritz series points at 2 guides, 3 parts and 2 symptoms, each named by the manufacturer's own procedure for this code.