Installation Guide
20 Rinnai Tankless Water Heater Installation and Operation Manual
Make sure that in case of freezing weather the water heater and its water lines are protected to
prevent freezing. Damage due to freezing is not covered by the warranty.
When connected to a 120-volt power supply, the water heater will not freeze when the outside air
temperature is as cold as -22°F (-30°C) for indoor installations or -4°F (-20°C) for outdoor
installations, when protected from direct wind exposure. Because of the “wind-chill” effect, any wind
or circulation of the air on the water heater will reduce its ability to protect itself from freezing.
In the event of a power failure and/or gas interruption at temperatures below freezing, the water
heater should manually be drained of all water to prevent freezing damage. In addition, drain the
condensate trap, drain line and pressure relief valve.
Loss of freeze protection may result in water damage from a burst heat exchanger or water lines.
The water heater may be drained manually. However, it is highly recommended to install the optional
Drain Down Kit accessory (part # 104000059) that will enable the water heater to immediately drain
upon loss of power (the condensate trap is not affected by the Drain Down Kit and must be manually
drained). Refer to section “3.6 Accessories” for more information on the Drain Down Kit.
The freeze protection features will not prevent the external piping and valves from freezing. It is
recommended that hot and cold water pipes be insulated. Pipe cover enclosures may be packed
with insulation for added freeze protection.
Figure 6: Freeze Protection Piping Diagram
Freeze Protecon Piping Diagram
Vacuum Breaker
1/2 in. Normally Open Solenoid Valve
Route Drain Per Local Code
Hot Water
Supply Line
Cold Water
Supply Line
3/4 in. Normally Closed Solenoid Valve
Legend
Vacuum Breaker
Pressure Relief
Valve Union
Drain Valve
Solenoid Valve
Ball Valve
Check Valve