Rheem Water Heater Error 29 – Condensate Neutralizer or Drain Blocked
Condensing Rheem tankless: acidic condensate can't drain, so the heater stops before it floods the burner.
Safety first · Consult a professional
Condensate is acidic – wear gloves and eye protection when handling the drain line. Don't open the heater cabinet. If you smell gas, leave the house without touching switches and call 911 or your gas utility from outside; if a CO alarm sounds, get outside and call 911.
- Gas appliance: no DIY repairs. If you smell gas, leave the building, do not use switches and call your gas utility’s emergency line from outside.
- Carbon monoxide is odorless. Keep a CO alarm near fuel-burning appliances; if it sounds, get everyone outside and call 911.
At a glance
Severity: Moderate
- Meaning
- Condensate Neutralizer or Drain Blocked
- Typical repair cost
- $0–$600
- DIY difficulty
- Moderate
Code 29 appears on Rheem's condensing (high-efficiency) tankless heaters. Burning gas this efficiently produces acidic condensate, which runs through a built-in neutralizer filled with calcium carbonate rock and then out a drain line. Rheem's Use & Care chart defines 29 as "neutralizer is clogged", while the newer LCD models show A029 for a blocked condensate line – in both cases condensate can't get out and the heater shuts down to keep water away from the burner and fan. Checking that the external drain line is open, sloped, unfrozen and not submerged is a reasonable owner task; cleaning or refilling the neutralizer inside the unit is something Rheem recommends leaving to a qualified technician. Related codes 92 and 93 warn that the neutralizer media needs replacing soon or must be replaced before the unit will run.
How it looks on the display
Model families & display variants
| Model family | Shows | Note |
|---|---|---|
| Condensing RTGH models with LED remote control | 29 | Use & Care chart: neutralizer is clogged. Companion codes 92 (neutralizer needs replacing soon) and 93 (must be replaced). |
| Newer condensing models with LCD user interface | A029 | Chart wording: blocked condensate line. Clear through the SERVICE menu after fixing the drain. |
| EcoNet app (Wi-Fi models) | 29 | Remote alert – the drain line and pump must be checked at the unit. |
Symptoms
- No hot water and code 29 (or A029) on the display
- Water dripping from the heater's bottom or pooling beneath it
- Drain line kinked, sagging, frozen or pushed into standing water
- Condensate pump full, humming or not switching on
- Code started during a cold spell when the drain runs through an unheated space
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Neutralizer media clogged or caked with sediment
- Drain line kinked, sagging, too small, or its end submerged or tied straight into a sewer line
- Drain line frozen in a garage, crawl space or outdoor run
- Condensate pump failed, unplugged or with a stuck float
- Debris or scale fragments blocking the internal condensate trap
- Vent pitched wrong, sending excess condensate or rain into the heater
Fix it step by step
Handle safety first
No gas smell and no CO alarm? Then put on gloves – condensate is acidic – and keep towels ready.
Tools: Gloves, Towels & shallow pan
Follow the drain line from end to end
Rheem requires PVC, CPVC or flexible tubing that slopes continuously downward, is at least as wide as the drain outlet and ends open to the air. Look for kinks, sags holding water, a crushed section, or an end sitting under water or connected directly to a sewer pipe.
Tools: Flashlight
Check the condensate pump
If the line runs to a small pump, confirm it's plugged in and powered, that its reservoir isn't overflowing and that the float moves freely. A pump that hums but doesn't discharge usually needs replacing.
Tools: Flashlight
Thaw a frozen line gently
In cold weather, warm the exposed tubing with warm, damp towels until condensate flows. Never use a torch or heat gun on plastic drain lines. Afterward ask about insulation or heat tape for that section.
Tools: Towels & shallow pan
Reset per Rheem's sequence
Turn off hot taps, switch the heater off at the remote, wait about 5 minutes and switch it on; if needed unplug it for 30 seconds. LCD models: clear the alarm through the SERVICE menu.
Leave the neutralizer to a technician
If 29 returns with a clear drain line, the neutralizer or internal trap needs cleaning or new media. Rheem recommends a qualified service technician for this; mention any 92 or 93 codes you've seen.
How to reset 29
- Clear or thaw the external drain line and make sure condensate can run freely.
- Turn off hot taps, switch the heater off at the remote, wait about 5 minutes and switch it back on.
- If the code remains, unplug the unit for 30 seconds (LCD models: SERVICE > ENTER > Clear Alarms? > Yes).
- If 29 persists, switch the heater off and call for service – the neutralizer likely needs attention.
Where the parts are
- 1Flue
- 2Fan
- 3Heat exchanger
- 4Ignition electrode
- 5Gas valve
- 6Circulation pump
- 7Expansion tank
- 8Pressure gauge
- 9Temperature sensor
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Straighten, clear or thaw external drain line (owner) | Yes | $0–$20 |
| Reroute drain line or add insulation / heat tape | No | $100–$300 |
| Clean neutralizer and refill media (service visit) | No | $120–$300 |
| Replace condensate pump | No | $150–$350 |
| Correct vent pitch or termination | No | $200–$600 |
Rough US estimates; technician call-out fees vary by region. Not a quote.
When to call a technician
Call your installer or a qualified plumber if code 29 returns after the drain line is clear, if you see 92 or 93, if water is leaking from inside the cabinet, or if the drain line is connected in a way that doesn't meet Rheem's requirements. Neutralizer service and internal trap cleaning happen inside the unit and are for trained technicians.
Frequently asked questions
What is the neutralizer on a Rheem tankless heater?
It's a built-in chamber filled with calcium carbonate rock that raises the pH of the acidic condensate before it drains. Over time the rock dissolves or cakes up, which is why Rheem also has reminder codes 92 and 93 for replacing it.
Why does code 29 show up mostly in winter?
A condensing heater makes the most condensate when incoming water is coldest, and drain lines in garages or outside walls can freeze. Either one backs condensate up to the neutralizer and trips the code.
Can I route the condensate line straight into my sewer pipe?
Rheem says not to connect the drain pipe directly to the sewer; the end should be open to the air. Follow local code for disposal, which may include a neutralizer and an air gap at a floor drain or standpipe.
Does code 29 appear on non-condensing Rheem models?
No. Only condensing tankless heaters have a condensate trap and neutralizer, so code 29 belongs to those models.
Sources
- Official Rheem user documentation and support pages (facts only; wording is our own)
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