Size Your Heating DuctsHeating ducts play a crucial role in routing heated air around your home. When installing heating ducts, sizing is very important if your home is to have the correct heating requirements. Installing smaller ductwork makes your heater run more frequently in a bid to keep your home at the correct temperature. On the other hand, overly large ductwork will have an impact on energy bills.

For you to make your ductwork effective, you should size your heating duct by making the correct calculations. There are lots of scientific ways and charts used to arrive at this, but from a homeowner’s DIY perspective, there is a much easier way to go about it.

Step 1 – Measure Your Rooms

The square footage for each room that is to be heated is a very important parameter in figuring out the right sizing for your ductwork. Because these numbers will be fed into the next process, ensure that the measurements are as accurate as they can possibly be.

Step 2 – Know the Required CFM

CFM is an abbreviation for cubic feet per minute. This is another important number you will need which depends on the size of the heating unit you plan to install. You will have to do separate and independent load calculations in order to find the right unit to install for your home. After this, then you can figure out the right duct sizing.
The output of a heating and cooling system is approximately 400 CFM per ton. Therefore, to get the total output in CFM, multiply the number of tons of your unit by 400. The product divided by the total square footage of your home obtained in step one above should give you the number you will require to calculate the CFM you need for each room.

Assuming your heating and cooling unit is a 2.5 ton; its output would be 2.5 x 400 which is 1,000 CFM. If the total square footage of your home is 1,000, it will mean dividing 1,000 CFM by 1,000 square footage will give you 1. For each room, multiply the square footage by 1 to get the required CFM.

Step 3 – Use a Duct Calculator

This is the simplest way to measure the required ducting size for any particular room. You can download this calculator online. It is important to note that the diameter of the heating duct will directly depend on the size of the area to be heated.

Step 4 – Combine the Heating Requirements of the Different Rooms

If the spaces to be heated do not constitute the entire house, simply add the requirements of those specific rooms in your calculations. Because depending on the size, each room will have a different CFM, ensure you measure each room accurately. Assuming one room needs 200 CFM and the other 100 CFM then the total will simply be 300 CFM. The diameter of your ducting should then be based on this arithmetic total.

The last step is the installation of the appropriate duct size having gone through the above calculations. Because ductwork installed incorrectly affects the heating capacity of your system, ensure the joints are securely done and the installation fixed as per the industry standard.

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