State Water Heater E29 Error Code — What It Means
The E29 error code on State condensing tankless water heaters indicates a problem draining condensate from the unit’s neutralizer and drain system. This code appears only on high-efficiency condensing models, not across all State product lines. The heater has detected a restriction, improper drain configuration, or neutralizer-related issue that is preventing normal condensate flow and could cause backup inside the unit.
The code is part of the fault family used on A. O. Smith and State-branded condensing tankless units. It specifically signals that condensate is not draining normally through the neutralizer and drain path. The unit will not operate properly until the drainage issue is resolved and condensate can flow freely to the termination point.
Common Causes
- Blocked condensate drain line Debris, scale, or sediment inside the drain tubing is the most common cause of E29 faults.
- Improper drain piping layout Undersized tubing (less than 1/2 inch ID), upward slopes, trapped sections, or excessive length prevent gravity drainage.
- Clogged or faulty neutralizer The neutralizer cartridge can become waterlogged, clogged with media breakdown, or physically damaged and restrict flow.
- Frozen condensate line When the drain terminates outdoors in freezing weather, ice blockage can stop drainage completely.
- Wiring or sensor connection issues Loose or corroded connections at the neutralizer sensor or control board can trigger false E29 codes even when drainage is clear.
Step-by-Step Fix
- Verify your model is a condensing State tankless unit and confirm the display shows E29 or code 29.
- Inspect the condensate drain line from the unit to the termination point for visible kinks, blockages, debris, or improper slope that would prevent gravity flow.
- Check drain line sizing and layout to confirm it is plastic, at least 1/2 inch inner diameter, and runs as short and direct as possible with continuous downward slope to the drain.
- Remove and inspect the neutralizer assembly for clogs, waterlogging, or media breakdown, and clear or replace the cartridge if needed.
- Look for freeze damage if the drain terminates outside, thaw any ice blockage, and relocate or insulate the drain line to prevent recurrence.
- Check wiring connections at the neutralizer sensor and control board for looseness, corrosion, or damage if the drainage path is clear.
- Restore power and monitor the unit during a call for hot water to verify condensate flows freely and the E29 code does not return.
Parts Often Needed
| Part | Notes |
|---|---|
| Condensate neutralizer cartridge | Amazon | Replacement neutralizer assembly for your specific State condensing tankless model. |
| Condensate drain tubing | Amazon | Plastic tubing, minimum 1/2 inch inner diameter, to replace damaged or undersized drain line. |
| Neutralizer sensor wiring harness | Amazon | If wiring to the neutralizer or control board is corroded or damaged and cleaning does not resolve the fault. |
When to Call a Pro
Call a licensed plumber or tankless water heater technician if you cannot safely access the condensate drain line or neutralizer, if the code persists after clearing visible blockages and verifying proper drain layout, or if you suspect control board or sensor failure. Persistent E29 faults after drainage and wiring checks typically require neutralizer replacement or control board diagnostics that need specialized tools and manufacturer training. A professional can also correct improper drain piping geometry and confirm the unit meets local venting and condensate disposal codes.