Showing Posts From
Ductwork
Duct Size Chart: How to Match Duct Size to CFM
A round duct size chart by CFM, what a ductulator actually does, the friction-rate and velocity rules behind it, how to convert round to rectangular, and how to size supply vs return ducts.
Return Air Duct Sizing: How to Size the Return Side
How to size return air ducts: why returns must match supply airflow, a return duct size chart by CFM, single vs multiple returns, filter grille sizing, and the static-pressure problems undersizing causes.
How Much Does Ductwork Replacement Cost? (2026 Pricing)
What new or replacement ductwork costs — by the foot, by the run, and for a whole house. The factors that move the price, repair vs full replacement, and how to estimate your job.
What Is CFM and How to Calculate It
CFM is the volume of air your HVAC system moves per minute. What it means, the 400 CFM per ton rule, the formula to size airflow per room, and how to measure it.
HVAC Static Pressure: How to Test It and What the Numbers Mean
How to measure total external static pressure (TESP), the normal range for residential systems, and how high or low readings point to specific duct and equipment problems.
HVAC Duct Sizing: Manual D vs Rules of Thumb
How to size HVAC ducts using the Manual D friction rate method and simplified rules of thumb, with duct velocity limits and why wrong sizing causes comfort problems.