Flexible ducts are fairly easy to install and will often cost less than the rigid ductwork.
Flex duct vs sheet metal duct.
That leaves rigid sheet metal often called hard pipe.
There s duct board rigid fiberglass with a foil facing but in my opinion that s worse than flex.
While flex ducts work best for short runs in a trunk and branch system metal duct works best for entire air distribution systems.
Their shape and size also allows them to be installed in locations that would not accept full sized sheet metal ductwork.
Alternatives to flex duct.
This is a great decision.
25 feet should it be ductboard or metal and is hard pipe runs preferable over flex.
More than likely.
Rigid metal is more likely to be installed without constrictions whereas flex duct can easily be pinched down.
Metal ductwork needs design measurement and installation by or with the help of an hvac professional.
While they tend not to last as long as sheet metal they are very cost effective.
Rigid metal is installed then mastic is applied to air seal then insulation is applied on the outside so there is less chance of fibers getting into your air stream.
Well if we re not going to use flex what s left.
While sheet metal ductwork tends to be a better long term choice flexible ductwork has the advantage of relatively low upfront cost and versatility.
If any duct product should be banned it s duct board.
Flex must be oversized at least one duct size.
Duct board vs metal plenums supply is on perferable over the other.
Most often flex duct is used to reduce cost or in places where metal duct work will not fit.
Air flow in a flex duct tends to tumble probably because of the rib like intrusion every inch or so.
Flexible ducts are made out of corrugated plastic often wrapped in insulation.
Air flow in a steel duct tends to travel smoothly in a coil like motion.
If i am going to have a supply plenum run for approx.
Even when doing this the flex duct creates much more resistance.