What smoke spot number represents correct combustion in newer burners?

What smoke spot number represents correct combustion in newer burners?
 
  A) 1 or less B) 1 or more C) 0 D) 2 or less

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[Ques. 2] You are using the static pressure drop method to check airflow. After making an adjustment to the system airflow, the static pressure drop across the coil increases. This indicates that:
 
  A) The evaporator coil became clogged during the adjustment period.
  B) The airflow has increased.
  C) Static pressure drop is not a reliable way to check system airflow.
  D) The airflow has decreased.

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[Ques. 3] How are water pumps in hydronic heating systems checked?
 
  A) By measuring the water flow in the system
  B) By measuring the pump motor RPM using a digital tachometer
  C) By measuring the impeller RPM using a stroboscope
  D) By measuring the temperature of the pump motor

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[Ques. 4] What do modern hydronic systems use to circulate the hot water?
 
  A) Gravity B) Pumps C) Fans D) Convection

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[Ques. 5] Two common methods for measuring airflow in residential systems are:
 
  A) Electronic flow hoods. B) Fan tip speed and a fan curve plot.
  C) Temperature rise or static pressure drop. D) Velocity pressure transducers.