The following terms are important for understanding the Join with Transition feature for HVAC:

• Tolerance: Tolerance is the maximum linear distance between the two ducts. If the ducts are non-colinear then it will project the port point to the center line of the other duct and that distance is considered for tolerance. This distance as shown below, is referred to as a linear distance.
  
  
  

  If this distance is more than the tolerance, then an error message will be displayed in the message center and transition will not be placed.

• Maximum Angle: The Maximum Angle is used to calculate the run and rise offset. The run offset is the difference in the y-direction, while the rise offset is the difference in the z-direction. These offsets are necessary when the ducts vary in shape, size, and alignment.

  To determine the run offset, the angle is checked with the Maximum Angle (which is set in the dialog) using the y-direction displacement and the linear distance between the two ducts. Similarly, the rise offset is checked using the z-direction offset and the linear distance between the two ducts.

  
  
  
• Type Property: The transition type is determined by the Type property of the first selected duct during the Join tool.
• Insulation and Insulation Thickness: The insulation material and insulation thickness of the transition are determined by the properties of the first duct selected during the Join tool execution.
• Length Effective for Custom Transitions: When adding a custom transition, the Length property specifies the linear distance for all transitions from a specified or concentric transition. If the transition is non-spec or custom, the Length Effective property indicates the distance between the two ports, while the Length property represents the linear distance between two ducts.