Your main objective in any duct system is to provide not only proper design and distribution of the air system but a duct system that is tight, well supported and free of moisture and condensate.
If you presently have a sheet metal duct system in your house wrap the exterior of the sheet metal for better insulation qualities and more efficient operation of the system. We stock duct wrap for this type of application.
Also seal any leaks as these leaks can cause significant energy losses and reduce the capacity of the system.
Flex Duct and Duct Tapes
The most abused material in a duct system is flex duct! When used properly it can be a labor saver and work very well. However when abused this material can cause the worst system performance. Why?? The worst duct system is one where a box of either sheet metal is used on the supply side of the air handler and/or furnace and then flex duct is run like spaghetti to all the diffusers in the house. Elbows, sharp bends, improperly supported this material will collapse thus creating significant air losses and air flow. This is not a duct system, this is a butcher job.
A properly designed and installed duct system will have a main supply trunk that runs the distance of the house with only 6 or 8 foot maximum lengths of flex duct to the diffusers. In commercial and industrial applications, we do not design a system with more than 4 to 6' take offs of flex duct to the diffusers and then there cannot be any elbows in the flex. This is code for Pennsylvania and there's a very good reason for this code. Again excessive use of flex duct will result in collapse of the flex either immediately or over time resulting on poor air flow.
Another major problem with this material is it is usually never properly supported. There are special supports and hanger material for flex duct, not wire or duct tape. Also note that duct tape that is sold in Home Centers and other consumer outlets is not the duct tape that should be used on an HVAC system. The glue used in this type of duct system will quickly dry out due to the temperatures it is exposed to and will leave a residue behind when removed making it impossible to apply a proper duct tape. This duct tape when used in attics will fail rapidly also because of the high temperatures. Only use the proper tape for the proper application that is rated and used by professionals. You as a consumer don't have access to the proper tapes in Do It Yourself Centers or discount stores.
Use only UL and SMACNA rated tapes that are specifically and professionally manufactured for the extremes of temperature and HVAC duct systems. You do not have access to these tapes in consumer outlets. These are the quality tapes that DESCO provides to you.
Use only properly designed and fabricated materials for supporting your duct system and components.
When a take off is made from a main plenum to the diffuser we supply all types whether it is from metal duct or fiberglass duct board. We recommend that all take offs are with balancing dampers so the air flow is balanced at the main trunk rather that at the diffuser. This eliminates noisy air at the diffuser and a much better design.
Typical flex duct tools for cutting flex duct
Types of take offs and boots