Rinnai 25: Condensate Trap Error
Condensing Rinnai models produce acidic condensate as a normal byproduct of high efficiency, and code 25 shows up when that condensate has nowhere left to go — the trap or drain line is full or blocked.
Applies to: Rinnai condensing water heaters (models that produce condensate).
What it means
Condensate Trap Error — the condensate drain system is full or blocked. Standard, non-condensing Rinnai models don't have this component at all, so this code is specific to the higher-efficiency condensing line.
Most common causes
The blockage is usually one of these:
- Condensate container/trap is full
- Condensate drain line is blocked or kinked
- Failed condensate trap
What you can safely check yourself
This is a genuinely accessible check for most owners:
- Check the condensate drain line and container where it exits the unit for visible blockage or a full container, and clear it if you can safely access it
- Make sure the drain line has a slight downward slope with no kinks
When to call a professional
The blockage isn't in an accessible spot, you see water leaking near the trap, or clearing it doesn't resolve the code.
Condensate is mildly acidic — avoid skin contact and rinse the area afterward if you clear it yourself; anything beyond an accessible external line is a job for a plumber.
What the fix costs
Clearing an accessible condensate line yourself is free. If a technician needs to inspect or replace the trap, that's typically a modest repair — often in the $100–$300 range as part of a standard service call (Angi, Fixr cost guides), well below what some of the more involved combustion faults run. Leaks near the trap are worth addressing quickly, since condensate can be corrosive to nearby metal components over time.
Related codes
- Rinnai LC — Scale Build-Up Warning
- Rinnai 32 — Water Temperature Sensor Fault
- Rinnai 16 — Over Temperature Warning
- Symptom: water heater leaking from the base or bottom
All Rinnai codes
Every Rinnai water heater fault code — the full list on one page.
Sources
- Rinnai condensing tankless water heater installation manual, condensate drainage section (manufacturer documentation)