Cfm Flow Flexible Vent Vs Sheet Metal Ducting

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.

Cfm flow flexible vent vs sheet metal ducting.

Always stagger take off ducts by 12 to maintain pressure. At 0 compression the maximum static pressure was 0 225 i w c. 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. The performance of flex duct at 15 compression is significantly worse than sheet metal and also worse than flex at 4 compression.

It was suggested by a moisture control co to have the ducts looked at some needed to be repaired. 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. While sheet metal ductwork tends to be a better long term choice flexible ductwork has the advantage of relatively low upfront cost and versatility.

It all depends on the unique needs of your home and your budget. Sheet metal ducts are less likely to incur dangerous mold and growths because their surfaces are non porous and smooth. Last take off run to be located 12 18 from end. 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 not hating on metal pipe but flex duct is more practical in many applications. In order to maintain velocity reduce duct size. 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 4 compression it rose to 0 8 i w c.

Duct elbows square throat no. Flexible ducts are fairly easy to install and will often cost less than the rigid ductwork. We have the original galvanized sheet metal ducts in our basement for the hvac. Use insulated duct or duct board in unheated spaces.

Flexible duct work must be stretched tightly for maximum air flow. 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. We can tell it s gotten worse than at 4 compression because the scale of static pressure has increased. 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. Metal ductwork needs design measurement and installation by or with the help of an hvac professional. So far we have gotten 4 estimates 2 companies say we need to tear out all the old ducts because they are.