Noritz Code 29: Condensate Drain Blocked

The Short Answer: In Noritz’s NRC1111 owner’s guide, code 29 means clogging of the condensate trap or drain pipe. Condensing Noritz heaters produce acidic water when they fire, and the heater stops if that water can’t drain. Noritz tells owners to check whether the condensate drain pipe is clogged or frozen, then contact the installer or Noritz. Look for kinks, freezing, a full condensate pump or a blocked neutralizer.

Why the heater stops

Condensing tankless heaters such as the Noritz NRC and EZ series cool their exhaust enough that water condenses inside the heater. That condensate runs through an internal trap and out a drain line, often through a neutralizer, to a floor drain, standpipe or condensate pump. If the water backs up, it can reach the burner and electronics. Code 29 stops the heater before that happens.

Noritz’s owner’s guide also notes that condensate is acidic, that local code may require a neutralizer before disposal, and that an external neutralizer’s media needs periodic replacement according to the neutralizer maker’s instructions.

Code 29 should only appear on condensing models. If you have a non-condensing Noritz with a metal vent and no condensate drain, confirm the code against the guide for your model.

Where the blockage usually is

What you can check safely

1. Note the code and photograph the display.
2. Follow the condensate line from the heater to its end. Straighten kinks, and look for low spots and sections running uphill.
3. Check for ice if the line runs outside or through a cold space. Gentle warmth such as warm air can thaw it. Don’t use an open flame.
4. Check the condensate pump, if there is one. Make sure it’s plugged in and running, and that its outlet line is clear.
5. Look at the neutralizer, if there is one. Replacing exhausted media is routine maintenance. Follow the neutralizer maker’s instructions.
6. Reset once by turning the unit off and on at the remote controller after the drain is clear. If 29 returns, call the installer.

Don’t take apart the internal condensate trap. Noritz’s guide warns that the condensate trap must be filled with water after the unit is drained or serviced, and that failing to do so could let exhaust gas escape, with a risk of severe injury or death. That reassembly and refilling should be left to the installer or a technician.

What the installer or technician will check

They will clear and inspect the internal trap and refill it. They check that the drain line is the right size and slopes continuously downhill, and add an air gap or relocate the termination if needed. They protect outdoor sections from freezing and replace or service the neutralizer or pump. They also check that the vent is sloped correctly, because vent condensate drains back through the heater’s condensate system.

Frequently Asked Questions

Q: Is code 29 the same as a neutralizer replacement reminder? A: Not in the NRC1111 guide, which describes 29 as clogging of the condensate trap or drain pipe. A worn-out neutralizer can be the thing clogging the drain, so it’s worth checking, but the code is about drainage.

Q: Code 29 only appears on very cold nights. Why? A: A section of condensate line outdoors or in an unheated space is probably freezing. The installer can reroute it, insulate it, or add heat tracing.

Q: Is it safe to run the heater with the condensate line in a bucket? A: Only as a short-term measure if the bucket can’t overflow and nobody can trip over it, and only if the heater runs without codes. Condensate is acidic, so empty it carefully and get the drain fixed.