Rinnai Rinnai RSC160iN Condensing Combi Boiler FREEZE DAMAGE Error Fix: Freeze / Cold Weather Damage

Error code FREEZE DAMAGE on the Rinnai Rinnai RSC160iN Condensing Combi Boiler means: Freeze / Cold Weather Damage. The tankless water heater has been damaged by freezing temperatures. Rinnai tankless units have built-in freeze protection that activates the unit's internal heater and may briefly fire the burner when the internal temperature drops below approximately 37°F. However, this freeze protection requires electrical power and only protects the internal components — it does NOT protect external piping, water supply lines, or drain lines. If the unit loses power during freezing weather, or if exposed external pipes freeze, serious damage can occur including: (1) Cracked heat exchanger — water expands when it freezes, cracking the copper heat exchanger tubes. This is the most expensive repair ($500-1500). (2) Burst water pipes/fittings connected to the unit. (3) Cracked condensate trap (condensing models). (4) Damaged flow sensor, thermistors, and other internal components. Prevention: never disconnect power from the unit during winter (the freeze protection needs electricity). Insulate all exposed water pipes near the unit. On outdoor installations, install a freeze protection drain valve kit. If the home will be vacant during winter, either maintain heat and power, or properly drain the unit and all associated piping. Rinnai provides detailed freeze protection guidance at rinnai.us.

The most successful fix is "Replace Cracked Heat Exchanger and Repair Freeze Damage" (hard difficulty, ~180 minutes). This fix costs nothing. HomeMD has 2 community-ranked fixes for this error.

This error is rated critical severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Replace Cracked Heat Exchanger and Repair Freeze Damage") is rated hard difficulty and takes about 180 minutes. Tools needed: Pipe wrench, T20 Torx screwdriver, Multimeter, Leak detection spray.

DIY cost: $0. Professional repair typically costs $800-$1500. Many homeowners save money by trying the top-ranked community fix first.

The Rinnai Rinnai RSC160iN Condensing Combi Boiler has 8 other known error codes, including: 02 (Ignition Failure), 03 (Bath Fill Function Abnormality), 05 (Blocked Exhaust / Air Supply), 10 (Blocked Exhaust — Air Pressure Switch), 11 (No Ignition), and 3 more.

Error code FREEZE DAMAGE also appears on 8 other Rinnai models: Rinnai RE180iN RE Series Non-Condensing Tankless Water Heater, Rinnai RL75iN RL Series Tankless Water Heater, Rinnai RL94iN RL Series Tankless Water Heater, Rinnai RU130iN Sensei Super High Efficiency Plus Tankless Water Heater, Rinnai RU199iN Sensei Super High Efficiency Plus Tankless Water Heater, Rinnai RUR199iN Sensei Recirculating Tankless Water Heater, and 2 more. The fix may vary by model, so check each model's specific page for tailored repair steps.