A.O. Smith 710 ASME Service Manual page 71

<Deactivate condition>
When the computer checks for these temperatures during the fan motor operation as freeze
protection, the Automatic fan motor system will deactivate if:
T > 39°F and T
in out
where T is the temperature of inlet thermistor and T
in
thermistor and T is the temperature of the mixing thermistor.
MIX
T > T
out
T > 50°F and T
in
> 39°F and T > 39°F and "Flow sensor detects flow rate for 1min"
MIX
+ 3.6°F
in
OR
> 50°F and T > 50°F
out MIX
OR
is the temperature of the output
out
71
CONFIDENTIAL
710 / 710 ASME Service Manual
Ver. 1.00