Noritz Code 29: Neutralizer Lockout

The Short Answer: On condensing Noritz NRC, NRCP, EZ, and NCC units, 29 is the condensate-neutralizer cartridge — media spent, remaining-life expired, or the switch saying replace it. It is not an igniter code. Photograph it. Service the cartridge and the drain path. One reset. A 29 that returns, or water on the PCB, is licensed. Non-condensing NR/N units should not be throwing 29.

Search Intent & The Real Problem

The remote or the 7-seg says 29. The shower died, or it still runs and the code will not leave. High-efficiency Noritz makes acidic condensate on purpose. That water is supposed to pass through a neutralizing cartridge (calcium carbonate media) before it hits a drain. When the media is exhausted, the board posts 29. People sand flame rods. Related wet paths: Noritz from the bottom, Navien condensate, Rinnai 25, tankless drains excessively. Lukewarm with no 29 is a different job.

What other guides get wrong

They paste a generic “heat exchanger overheating” table onto Noritz 29. On these condensing chassis, 29 is the neutralizer, not a 14/16 overheat and not a Rinnai 12. They tell you to pinch the condensate hose so it “stops leaking.” A pinched hose overflows into the cabinet, kills the board, and can add a code 10-class air fault after the trap floods. They vinegar-flush the potable exchanger for a 29. Scale is a different code family. And they reset 29 twenty times with a dry cartridge still in the pot.

Step-by-Step Troubleshooting

Step 1: Confirm 29 on a condensing Noritz

• What to look for: PVC or vinyl condensate drain, PVC vent (condensing). Rating plate: NRC, NRCP, EZ, NCC. A stainless Category III NR with a “29” is a misread or the wrong brand’s chart. Photo of the code and the plate before you kill power.
• Required tools: Phone camera.

Step 2: External drain — kink, freeze, uphill, glue blob

A spent cartridge is the textbook 29. A flooded path fakes it. Unkink first so you do not buy media for a crushed hose.

• What to look for: Hose crushed by the unit, run uphill to a sink, stuffed into a standpipe with no air gap, frozen at an outdoor termination. Neutralizer jug packed so nothing leaves. Cool drip at a loose union that looks like a bottom leak.
• Required tools: Eyes, wet/dry vac on the external line only.

Unkink. Thaw a frozen outdoor hose with warm air, not a torch. Glue in the trap from the original install is a licensed cut-out. Do not pinch the line.

Step 3: Neutralizer cartridge and media — the actual 29

• What to look for: Cartridge or media pot at the bottom of the cabinet or in-line on the condensate hose. Media that has gone to mush, is missing, or has never been changed on a 5–10 year condensing unit. Some firmware warns and keeps firing; some lock the burner. The jacket sheet on that Noritz is law. A field condensate pump with a full reservoir will also keep the tray wet so the float never clears — empty the pump, do not jumper the float.
• Required tools: Power off. Bucket. Manufacturer cartridge or media — not aquarium gravel, not baking soda in a sock.

Replacing an accessible external cartridge is fair DIY if you can reseal the drain and you do not crack the pot. Internal trays, clipped sensors, and anything over a wet PCB are licensed. Do not run the unit with the cartridge removed “to see if 29 goes away.” Acid condensate on a copper drain or a concrete floor is how you buy a new slab.

Step 4: Inside the cabinet — stop if the board is wet

• What to look for: Water behind the front cover, mineral tracks on the PCB, trap overflowing inside. That is no longer a hose. Power stays off. Acid on electronics is a board replacement after the drain is fixed — not a hair dryer on a live PCB. Isolation valves if the water is hot (potable leak), not just cool condensate.
• Required tools: Flashlight. Do not pull the trap apart if you cannot reseal it.

A stream from inside the jacket with isolation closed (after residual drains) is an exchanger — Noritz leaking, not a 29 reset. House static over ~80 psi lifting a healthy PRV (150 psi / 210°F) is pressure, not condensate.

Step 5: One reset after the drain is real — then hire it

• What to look for: New or recharged media, drain free, pump empty and pumping, no water on the board. Power off 10–30 seconds. 29 gone, unit fires, cool condensate beads at the drain while it runs — that last part is normal. Same 29 on the next shower: licensed. Do not keep resetting a flooded cabinet. Do not purge the gas line because a 29 scared you.
• Required tools: Hand on the switch. No paperclip in the PCB.

Manifold pressure is irrelevant to a spent cartridge (NG often ~3.5–7 in. w.c. / LP ~10–11 in. w.c. — confirm the plate when a licensed tech is actually on combustion). A packed inlet screen causes no flow, not 29.

When DIY Ends: Calling a Licensed Pro

Stop at a wet PCB, a stream from inside the jacket, a frozen line in a wall, gas smell, a jumpered float, or a 29 that returns after a new cartridge. You may unkink the hose, empty a pump reservoir, swap an accessible external cartridge, and power-cycle once. Internal trap service, exchanger work, and board replacement are licensed. Noritz will not smile on an exchanger that ran with a blocked condensate line or a bypassed neutralizer switch.

Frequently Asked Questions

Q: What does Noritz code 29 mean? A: On condensing NRC / NRCP / EZ / NCC units, 29 is the condensate-neutralizer cartridge — media spent or the switch calling for replacement. Confirm the sticker on that cabinet. It is not an igniter or gas-valve code.

Q: Can I clear a Noritz 29 myself? A: If the hose is kinked, the pump reservoir is full, or an external cartridge is obviously exhausted, yes — then one reset. If the cabinet or board is wet, or 29 returns, hire a licensed tech.

Q: Is condensate dripping from a Noritz a leak? A: Cool drip from the drain fitting while it fires is normal condensate. Hot water from inside the jacket, or the T&P, is not — shut it down.