Increase.
You need to lower the resistance to air flow.
You need to lower the resistance to air flow.
Here's one link that may tell you by how much to increase the duct size.Do I increase or decrease the duct diameter to get more air flow?
And Moody's equation has me going in circles. Can we make assumptions about air flow and get existing duct sizes and go from there?That site also has that chart in SAE.
But, it doesn't tell you what size. Unless you knwo what friction rate you should be using.
I couldn't find this equivalent length method online for fittings for free, only links using the loss coefficient method.1-90° ell is 15' of TEL. A supply boot is 30', a start collar can be 15 to 35'