Families and Content Creation
Family taxonomy
Candidates must distinguish system families (ducts, pipes, walls - created in-project, not loadable) from loadable families (equipment, fixtures, terminals). Within loadable families, know the template types: equipment, pipe accessory, duct fitting, and the behavior of hosted versus non-hosted versus face-based elements. Hosted families fail when the host is deleted; face-based families are generally preferred for equipment placement on links or varied geometry.
Parameters and constraints
Understand parameter types (type versus instance), parameter data types (length, angle, family type, yes/no), and how formulas drive geometry. Formulas cannot create circular references, and units must match - a length parameter divided by a number yields a length. Constraints, reference planes, and dimension locking make geometry parametric; over-constraining produces errors. Shared parameters must be defined in a shared parameter file before being added to families or tags.
Connectors
Mechanical and plumbing families rely on connectors: shape, size, flow, and system classification. Connectors must be placed on a reference plane or face and oriented outward; a reversed connector causes the system to behave unexpectedly.
Traps and worked example
Traps: expecting a system family to be saved as an .rfa; forgetting that type parameters apply to all instances; and confusing a nested family's parameters with the host's. Worked example: to make a VAV box with a size-driven width, create a type parameter "Width," dimension the reference planes, select the dimension, and assign the parameter - then flex it in the Family Types dialog. If it fails to flex, a constraint is over-defined or a formula references itself.