I am building a house and had a question for the pros.
The house will be an insulated concrete form home that will be energy efficient and extremely well insulated and tight.
I followed manual D to determine my friction rate for duct design.
My issue is with the TEL calculations is the equivalents in manual D are based on a velocity of 900 FPM.
I will be nowhere near 900 FPM and more like 400-500.
My understanding of these equivalent lengths is that if you half the FPM the friction is 1/4 of what it is at 900 FPM.
Should I be designing TEL based on 1/4 of the manual D equivalents?
Obviously the resulting FR will be extremely different.
I appreciate any input from the Pros!!