Ductwork is the tubing that is connected to the HVAC system which is used to funnel air throughout the building. It is important to size your ducts accurately since ductwork too small will make your HVAC system overwork, and ductwork too large will lessen the speed of airflow.
Finding the right ductwork size, however, is not the easiest project, and a professional will most likely need to be consulted. As a matter of fact, certain building codes require air and heating systems to be in line with ACCA’s Manual D duct design.
In this blog, we will lead you through a few of the steps you can make towards finding the correct size of the ductwork for your residential building, before passing the project off to an HVAC professional.
Ductwork for Residential Projects
The first thing you will need to do is measure the square footage of your home. Measure the length and width of each room and multiply them together. Add all of the rooms together to get the total for the house. Jot down this information, as you will need it later.
Next, you can work a bit with the CFM – cubic feet per minute – of each room. The CFM of a room measures the airflow needed to correctly maintain the temperature in a room. To calculate the CFM of a room, you will have to know the size, in tons, of your HVAC unit. All HVAC units are measured in tons, and so this number should not be too difficult to find. Once you have this number, multiply it by 400, and then divide this result by the total square footage of the home. The result of this total calculation will give you the CFM number for that room.
Finally, you can calculate the friction loss of your ducts. Friction loss is measured by inserting a number of different variables into a complex calculation. These variables include things such as the number of turns, filters, grills, coils, and dampers in your system. Online, you should be able to find a calculator which allows you to insert these variables and which will produce the total friction loss of your ducts.
The above three steps – square footage of the home, CFM of each room, and the friction loss of the ducts – are ones which you can take in preparation for properly sizing your ductwork. The proper size of ductwork will be generated by including the above three factors into a very complicated calculation. An HVAC professional will be able to help you complete this calculation.