Rinnai M060C Installation And Operation Manual page 88

The boiler is equipped with two different methods of freeze protection, one for the boiler itself and
one for the system.
If the Supply Temperature thermistor, T1, observes a temperature less than 47°F, the boiler pump
will run for 2 minutes. The internal three way valve will alternate every minute to ensure
circulation through both the primary heat exchanger and the plate heat exchanger. If T1 observes a
temperature less than 39°F, the burner will fire for 30 seconds or until the T1 sensor observes a
temperature higher than 47°F. This feature cannot be disabled.
If the outdoor sensor observes a temperature between 25°F and 35°F, the boiler will operate for 10
minutes every 6 hours. If the outdoor sensor observes a temperature of 24°F or less, the boiler
pump will run continuously. This feature can be disabled via parameter 2.9.1.
When the system needs to be shutdown for extended periods of time, the boiler and all system
piping should be drained. The power and gas supply should then be disconnected from the boiler.
Freezing damage may occur if there is water remaining in the boiler or system piping. The plumbing
lines should also be blown out via compressed air.
88 Rinnai M-Series Condensing Boiler Combi Manual