Duct takeoffs have big shoes to fill. They are the avenue by which air moves from the main duct pipe to a new branch. Naturally, you want this transition to be as smooth as possible. Each new duct branch usually services another room in the home or building, and you want the air distribution to be the same for every room. So why does it feel a cool 68 degrees in the living room, and meanwhile the back bedroom is a sweltering 85, even though you have air flowing into that room? It could have something to do with your duct takeoffs. Here are a few things to consider:

Fast moving air doesn’t make 90-degree turns very well.

Your HVAC system’s blower shoots air through the supply plenum and then down the main duct. Everything is going fine until the air comes up to the first duct takeoff, and it’s at a 90-degree angle. Under certain circumstances, it’s possible that the air is shooting right past this duct takeoff. Why would this happen? Because turns of 90 degrees actually create air resistance. Consider changing the configuration of a 90-degree angle by fitting the duct with a square-to-round or conical duct takeoff.

Takeoff placement is important.

Most ductwork has twists, turns and rounded places along the supply duct line. Add in duct takeoffs, and you have a recipe for obstructed airflow. Consider this common design flaw: Let’s say your main supply line has a duct takeoff leading into room one and one leading into room two. The supply line ends with a large vent leading into the living room. With the air shooting down the supply line towards the central vent at the end, do you think any air will turn and flow into room one and room two? Likely not. This scenario can cause the opposite of your intended effect.

Think back to physics class.

Do you remember the Bernoulli Principle? In this common but flawed duct configuration, air can be sucked into the main supply line from room one and room two due to the air rushing towards the large main vent straight at the end of the supply line. Not an ideal situation if you want room one and room two to stay hot (or cool).

These are just a few of the main air duct issues HVAC professionals see every day. Are you experiencing heating and cooling issues in your house and think it might be due to your air duct supply lines or takeoffs? Call Rochester HVAC Experts for the highest quality HVAC service and installations you’ll find in the Rochester area and beyond.