The duct work for your home is very important, so after you’ve done your homework regarding which HVAC equipment you want installed, it is vital that the job is done right.
The rough-in is mostly concerned with reviewing the duct work. These are the “pipes” that will distribute the air to all areas of the home. The duct work is very important. If it’s not sized properly and run properly you will not get good flow of air. Additionally, the “return air” part of the system is very important as this is how the air circulates back to the system. If you don’t have enough return air the system will not work as efficiently and will likely be noisy.
The material used for the duct work is critical to the delivery and return of air. The use of Flex duct is common by builders who are trying to cut costs as it is less expensive and easy to install. It is very flexible and cannot be run without a lot of dips. The best example on how this affects the flow of air is to take a small section (approximately 6’) of a garden hose and roll it up then below through one end. Note how much pressure it takes to blow air through this. Now lay the hose flat and repeat the process. You will notice a significant difference in the pressure needed to blow air through the hose. The use of the flex duct versus the use of the metal duct is the same principle. Lastly, the R factor of the flex duct will be less than the R factor of the wrap available for the metal duct. This helps keep the air the temperature it should be.
Once the HVAC rough-in is complete, you’re almost finished! Now you’re ready for the electrical and technology rough-ins.