A.O. Smith T-H2-DV Service Manual page 86

To sum it up in a chart:
5 minutes have elapsed
since prior operation?
No
Yes
Yes
Yes
Yes
Ceramic heating blocks
The blocks will only activate based on what the freeze protection thermostat senses. The thermostat is
located on the intake port for T-H2-DV and left side of compter board for T-H2-OS. Electrical power is
required for this feature to operate.
The heating blocks will activate if the thermostat senses a surrounding temperature below 36.5°F.
Once they are on, the heating blocks will only deactivate if surrounding temperatures reach above
.
46.4°F
Inlet thermistor
temperature
Any
Above 46°F
Any
Any
46°F and above
T-H2-DV/T-H2-OS Service Manual
Output thermistor
temperature
Any
Any
Above 37°F
37°F and below
37°F and below
86
CONFIDENTIAL
Ver. 1.01
Will automatic firing be
activated?
NO
NO
NO
NO
YES