HVACopediaRinnai · Tankless water heater · Freeze protection
Built-in freeze protection and power loss
What happens, in order
- While the unit has 120 V power, built-in freeze protection heaters keep the unit from freezing
- Protection works down to -22 F (-30 C) indoors or -4 F (-20 C) outdoors, with no direct wind on the unit
- Wind and air movement over the unit reduce this protection
- Heaters do not protect the external piping and valves, so insulate hot and cold lines
- If power or gas is lost in freezing weather, drain the water heater by hand and also drain the condensate trap, drain line and pressure relief valve
- Optional drain-down kit drains the unit right away on power loss (kit 104000285 on RX)
Timings and thresholds
| Item | Value |
|---|---|
| Indoor limit | -22 F (-30 C) |
| Outdoor limit | -4 F (-20 C) |
Applies to: Rinnai condensing tankless water heaters
Models
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Source: Rinnai tankless water heater Installation and Operation Manuals (SENSEI RX 100000839, RSC SENSEI 100000773, N-Series Residential 100000467), freeze protection section. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.