while reviewing different revit mep models, I keep noticing the same types of modeling issues appearing again and again.

some of the most common ones:

• open connectors / open pipe or duct ends
sometimes pipes or ducts are left with open connectors.
impact: systems may not calculate correctly and the network remains incomplete.

• fully disconnected elements
elements that are placed in the model but not connected to anything.
impact: they don’t actually belong to any working system and can easily go unnoticed.

• dangling fittings
fittings where one connector is left open.
impact: usually a sign that the system modeling is unfinished.

• orphan equipment
equipment families placed in the model but not connected to any system.
impact: they won’t behave correctly in system analysis or calculations.

• elements with no system assigned
pipes, ducts, or equipment without a system name.
impact: this can affect schedules, calculations, and overall system organization.

• connectors that are very close but not actually joined
sometimes elements look connected visually but are slightly misaligned.
impact: the system appears correct in the model, but technically it’s still disconnected.

• duplicate elements in the same location
two identical elements placed on top of each other.
impact: this can lead to incorrect quantities, coordination issues, or confusion later.

individually these might seem like small issues, but they often cause bigger problems later with system calculations, schedules, coordination, and overall model reliability.

i’m curious about the experience of other bim / mep engineers.

what are the most common issues you usually run into in revit mep models?

• unconnected systems
• wrong system classifications
• duplicate elements
• missing flow parameters
• poorly built family connectors

it would be great to hear what kinds of checks you find most useful when doing mep model qa/qc.