When working with ducts, we often need to convert CFM to FPM. Basically, we are converting airflow in terms of Cubic Feet Per Minute (CFM or ft3/min) to air velocity in terms of Feet Per Minute (FPM or ft/min). Here, we have everything you need to convert CFM to FPM for both round ducts (1st … Read more
Air velocity (FPS) and airflow (CFM) are closely connected. In many cases, you will need to convert FPS to CFM; basically, you are converting the speed of air in Feet Per Second (FPS or ft/s) to airflow in Cubic Feet Per Minute (CFM or ft3/min). We are going to help you out with the FPS … Read more
What size return ducts do I need? Adequately sizing return ducts is (fairly) easy. We usually need to figure out CFMs based on HVAC tonnage, and select the right round or rectangular duct size. We will show you exactly how to determine the return duct size. Further on, you will also find a very helpful … Read more
When working with ducts, you might need to convert FPM to CFM. Basically, we want to know how much airflow (measured in CFM or Cubic Feet Per Minute) we get at a certain airflow velocity (measured in FPM or Feet Per Minute). Now, the relationship between FPM and CFM is determined by the cross-section of … Read more
With a bathroom exhaust fan, you have to install adequately sized ducting. The problem is that there is no universal standard bathroom exhaust fan duct size. We are going to look at all duct sizes for bathroom fans (you can check the all-encompassing 4-9 inches ducts fitting 50-250 CFM exhaust fans further on). Namely, bathroom … Read more
Ducts are an essential part of HVAC and our household. They experience both the highest temperatures (heating season) and the coolest temperatures (cooling season). To make them as efficient as possible, it makes sense to insulate air ducts. When is insulation required on air ducts? Most ducts require insulation with a specified R-value; this is … Read more
Today, we are going to look into a tricky HVAC thing: How to increase airflow to one room? If you have explored this topic on the internet, a lot of stuff you get for how to increase airflow to one room is about opening windows, HVAC maintenance, and changing filters, just to name a few … Read more
HVAC units work like lungs. They need to inhale air (supply vents) and exhale air (return vents). If your return vents don’t return enough air, you will have a series of problems. We are going to look at the symptoms of not enough return air from vents. First of all, it is important to understand … Read more
In HVAC, we have to choose the right return air grille size. Everybody knows that an adequately sized grill will ensure smooth airflow (essential). However, not everybody knows what return grill size to choose. What size return air grille do you need? There are two ways how to figure out what return grille size you … Read more
If you want to replace rectangular ducts with round ducts, you will have to use the rectangular to round duct formula. This formula determines the needed round duct diameter you need to match the rectangular duct airflow. In HVAC, this is known as equivalent diameter. You will need a sufficient diameter of round ducts to … Read more