Flex Duct Vs Metal Duct

One very important aspect of duct design to consider is the differences between flexible hvac ductwork and rigid duct insulation.

Flex duct vs metal duct.

Flex duct was designed to only be used in 3 to 5 ft lengths to make it easier to connect the metal duct system to the register boot. Sheetmetal ducts are always better for airflow purposes. Their shape and size also allows them to be installed in locations that would not accept full sized sheet metal ductwork. I also pull the flex tight reducing the folds but allow it to relax before securing.

With proper information you can correctly design your hvac system with ductwork that suits your needs. Fiberglass lined air ducts some sheet metal air ducts are lined with an external or internal fiberglass duct liner. We install sheetmetal all the time restricting our installers to a maximum of 15 foot supply branch runs of s t r e t c h e d flex ducts. Metal duct creates less drag and maintains a better velocity when installed properly.

Or up size did that too for a cold air return 6 metal to 8 flex. Sheet metal air ducts are the most durable type of air duct construction and because of their non porous surface are the least likely to have mold or biological growth. Metal is also much noisier than flex. Flex ductwork is recommended in attics or spaces that are not conditioned.

The pre insulated flex duct does hold the heat and cooling better than bare metal duct. This is because they re more versatile and flexible. A recent study indicates that the flow restrictions with flex duct are very substantially higher than even the most conservative tables in use. I ve used metal elbows for turns then flex for straight sections.

In comparison to metal duct flex duct is easier and faster to install. Metal ducts are more rigid due to the nature of steel making them ideal to build an entire hvac system. On the long run try using a short section of flex breaking up the metal duct. Flex ducts are better for existing trunk and branch heating and cooling systems.

The flex out performed the 6 in this case. While sheet metal ductwork tends to be a better long term choice flexible ductwork has the advantage of relatively low upfront cost and versatility. Metal in general if sized and installed correctly is considerably less restrictive than flex. A good approach is a hybrid between metal and flex.

Yet in order to save a few bucks many contractors will use flex for nearly the entire duct system.