flue air enthalpy sp point
| air | 
 The mixture of gases which surrounds the earth 
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| enthalpy | 
 Total heat content of a system 
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| flue | 
 Duct for exhausting combustion 
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| point | 
 Data point such as a sensor or actuator 
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| sp | 
 Point is a setpoint, soft point, internal control variable, schedule 
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