Low pressures are often measured in inches of water column or “WC. Like most units of measure, it has a very simple origin; in a water manometer, 1″ of water column is literally the amount of force it takes to raise the column of water by 1”. While some water manometers (water tubes) are still […]

Recommended Duct Velocities (FPM) Duct Type Residential Commercial / Institutional Industrial Main Ducts 700 – 900 1000 – 1300 1200 – 1800 Branch Ducts 500 – 700 600 – 900 800 – 1000   As service technicians, we are often expected to understand a bit about design to diagnose a problem fully. Duct velocity has many […]

The title says it all. It should be one of the first things you learn when you started. However, I have seen a lot of experienced techs who seldom (if ever) do it. When connecting to a tank, purge your hose by cracking the center connection at the manifold for a second. When connecting to […]