Plumbing & HVAC

Duct sizing, velocity, friction and equivalent lengths; leakage class and silencer loss; fans, grilles, VAV boxes and reheat coils; filtration and cleanroom airflow; pipe sizing for domestic water, gas and hydronics with Hazen-Williams losses; pumps, expansion tanks and relief valves; condensate, grease traps and trap primers; and the hangers and trapeze supports for all of it.

Whether the fluid is air or water. Both are sized from a flow and a permissible loss, but the loss that governs differs — air is a velocity and a noise limit, water is a head and a velocity limit that protects the pipe from erosion. A calculator that takes a flow without asking which is not answering either question.

The heat loss that sizes the plant, which is an insulation question; the electrical supply feeding the equipment; and the insulation wrapped around the duct.