Table of Contents
What are the methods of duct design?
There are actually six methods for designing low, medium, and high-pressure HVAC systems:
- Equal Friction Method.
- Static Regain Method.
- T-Method.
- Extended Plenum Method.
- Velocity Reduction Method.
- Constant Velocity Method.
What is a start collar HVAC?
A starting collar is used to connect a flat surface like a duct board to a round pipe duct.
What is a duct collar for?
At a main duct or plenum, a starting collar is installed for attaching a straight or split fitting for the ducts. Installing a collar is the first step when installing the system of ducts. The job requires an HVAC plan or a clear idea of the planned duct work and, in some cases, the ability to work in confined areas.
What are the methods for duct sizing?
Design Master HVAC can size ducts using three different methods: constant pressure drop, constant velocity, and static regain. All of these sizing methods are fairly straightforward.
What is FPM in HVAC?
feet per minute
Air velocity (distance traveled per unit of time) is most often expressed in feet per minute (FPM). Multiplying air velocity by the area of a duct allows you to determine the air volume flowing past a point in the duct per unit of time. Volume flow is generally measured in cubic feet per minute (CFM).
What is a take off duct?
Top takeoff is used to cut into plenum or rectangular duct to begin a trunk line or branch-like runs. It allows transition from an air plenum or square duct to a round pipe. This top take off is available in size for starting side from 6”x6” to 12”x 12” and for ending side from 6” to 8”.
How do you calculate duct cfm?
Calculating CFM
- CFM = FPM x Duct Cross Sectional Area.
- FPM = 4005 x √.45.
- FPM = 2,686.
- CFM = 2,686 x Duct Cross Sectional Area.
- A (Duct Cross Sectional Area) = X (height in feet) x Y (width in feet)
- A = 1.07 sq. feet.
- CFM = FPM x Duct Cross Sectional Area.
- CFM = 2,686 x 1.07 sq. feet.
What is FPM vs CFM?
FPM refers to the “air speed” produced by a dryer, as measured in Feet Per Minute. CFM is a measure of the “air flow,” stated in Cubic Feet per Minute. In other words, FPM is a measurement of how fast the air moves and CFM measures how much air is moved.
What is duct transition?
Duct Transition is an essential and indispensable component of HVAC ductwork. It connects the various sizes of ducting, different facilities parts, and varying materials of ventilation parts together to make sure there is a smooth and steady flow of air.
How far apart should duct take offs be?
This is the ‘Two-Foot Rule?. Ideally, you should allow at least 24′ between takeoffs and at the end of any duct run.