Rinnai Error Code 100: Air intake/exhaust blockage or full condensate trap (Combi Boiler)

Updated October 13, 2026 · by Aurora Star Tech Inc.

Rinnai error code 100 on a combi boiler means: Air intake/exhaust blockage or full condensate trap. It is also called Rinnai diagnostic code 100.

Critical severityCombi BoilerI-Series Plus 150K and smaller · I-Series Plus 175K and higher

Homeowner? What Rinnai code 100 means for you

Stop and call Your combi boiler is reporting: Air intake/exhaust blockage or full condensate trap. This code is a safety shutdown. Turn the combi boiler off and call a licensed technician. Do not keep resetting it. If you smell gas, leave the house and call your gas utility or 911 from outside.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rinnai error code 100 mean?

The control has detected a restriction in the intake or exhaust path. A backed-up condensate trap inside the boiler can also restrict airflow and trigger it.

Applies to: I-Series Plus boilers — 150K BTU and smaller and 175K BTU and higher (Combi and Solo)

Common causes of Rinnai code 100

Clogged or frozen condensate drain backing up the trap
Dirty inlet air filter
Blocked intake/exhaust terminations or debris in vent piping

A technician checks these and 5 other possible causes on site before replacing any part.

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Rinnai models that use code 100

IP060160C IP090099C IP090160C IP090199C IP120199C IP150199C IP175199C IP199199C

Other Rinnai Combi Boiler codes

Code	Meaning
021	DHW continuous operation time exceeded
110	Ignition failure
120	Flame failure (flame lost during operation)
140	Overheat switch tripped (heat exchanger overheating)
150	Venturi control fault
161	High DHW outgoing water temperature
170	Venturi blockage / position mismatch
180	Gas valve air/fuel adjustment limit reached
190	Electrical grounding / short in DC circuit
210	Data transfer error
220	Gas valve position not detected (reed switch)
250	Condensate pump switch tripped (accessory)

All Rinnai Combi Boiler error codes →

Rinnai code 100: homeowner questions

What does Rinnai code 100 mean?

Air intake/exhaust blockage or full condensate trap. The control has detected a restriction in the intake or exhaust path. A backed-up condensate trap inside the boiler can also restrict airflow and trigger it.

Is it safe to keep using my combi boiler with code 100?

No. Code 100 is a safety shutdown, so keep the combi boiler off until a licensed technician has checked it.

Can I reset Rinnai code 100 myself?

Do not keep resetting it. Repeated resets can hide a safety problem; a licensed technician needs to find the cause.

Who can fix Rinnai code 100 near me?

Aurora Star Tech Inc. repairs Rinnai combi boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Tankless Water Heater No Hot Water: What to Check · Boiler Not Heating: What to Check

Source: Rinnai Troubleshooting I-Series Plus Boiler Diagnostic Codes (800000375), p.4–5. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.