Duct elbows square throat no.
Cfm flow flexible vent vs sheet metal ducting.
Never locate ducts at the end of the trunk line run.
Also i think spider webs are more likely to form in metal versus flex.
I ve only been building since 1995 so i can t say for certain why we left the sheet metal guys behind but i suspect it was manly for cost reasons.
I don t know why but i have taken metal pipe apart to find a lot of crud which i don t think would live in flex duct.
Flexible duct work must be stretched tightly for maximum air flow.
In order to maintain velocity reduce duct size.
Flex duct 05 on most metal duct calculator round metal pipe 06 on most metal duct calculators field duct sizing chart rectangular sheet metal duct 07 on most metal duct calculators.
While flex ducts work best for short runs in a trunk and branch system metal duct works best for entire air distribution systems.
I am not hating on metal pipe but flex duct is more practical in many applications.
While sheet metal ductwork tends to be a better long term choice flexible ductwork has the advantage of relatively low upfront cost and versatility.
In this video i ll make a case for going back to rigid metal ducts for your trunk lines and keeping your flexable ducts to the last 10 or less of a.
At 0 compression the maximum static pressure was 0 225 i w c.
First let me start by saying i am not in the hvac business.
Last take off run to be located 12 18 from end.
Always stagger take off ducts by 12 to maintain pressure.
Sheet metal ducts are less likely to incur dangerous mold and growths because their surfaces are non porous and smooth.
16 up to 11 40 el 12 to 15 55 el 16 to 21 75 el 22 to 27 100 el 28 to 33 125 el return air system no.
I am the owner of a home built in the 50 s.
The performance of flex duct at 15 compression is significantly worse than sheet metal and also worse than flex at 4 compression.
So far we have gotten 4 estimates 2 companies say we need to tear out all the old ducts because they are.
Flexible ducts are fairly easy to install and will often cost less than the rigid ductwork.
Metal ductwork needs design measurement and installation by or with the help of an hvac professional.
At 4 compression it rose to 0 8 i w c.
810 cold air boot collar duct 45 65 el air flow dynamics duct sizing reference guide supply or return duct size capacity 09 to 10 pressure drop per 100 el.
I have seen many leaky metal ducts in crawl spaces as well.
We have the original galvanized sheet metal ducts in our basement for the hvac.
We can tell it s gotten worse than at 4 compression because the scale of static pressure has increased.
