HVAC Register sizing

[drummer0901]

I have a 30X 50 insulated steel building that I am installing a 4-ton split heat pump(got a deal used from a friend)

I have another friend that designed the duct work for me, and I have pestered him enough with questions, I thought I would ask here

The duct he designed is 16" (21ft) 14" (20ft) 12" (5ft) round insulated with 3" insulation.

He specd 6-8" takeoffs for the entire trunkline, but I want to mount registers straight to the trunkline and not run any more pipe.

My question, what size rectangular register equals the the same cfm as 8 takeoff? I'm located in Middle TN, summers are hot, and winter can get cool. Really just looking to make the shop reasonable to woodwork and wrench in.

Any help appreciated,

 

[PoorUB]

One run of 16" is a bit short for the CFM, in my opinion. Not terrible, But I would go to 18" right of the HP. Same with the 12", you need to go up one size. You need to design for 1600 CFM so eight take offs would be 200 CFM each. My info shows a 6x10 register is good for 200 CFM.

 

[drummer0901]

One run of 16" is a bit short for the CFM, in my opinion. Not terrible, But I would go to 18" right of the HP. Same with the 12", you need to go up one size. You need to design for 1600 CFM so eight take offs would be 200 CFM each. My info shows a 6x10 register is good for 200 CFM.

Thank you for your reply. I did fail to mention i had already installed the trunk line.

What issues will i run into with the trunk being slightly undersized?

To the get the most efficient use of heating and cooling, should i install the registers at a 45 angled towards the floor? The duct is hanging about 10 ft from the ground.

Again thank you for your help!

 

[PoorUB]

Thank you for your reply. I did fail to mention i had already installed the trunk line.

What issues will i run into with the trunk being slightly undersized?

To the get the most efficient use of heating and cooling, should i install the registers at a 45 angled towards the floor? The duct is hanging about 10 ft from the ground.

Again thank you for your help!

If you have it up, run with it, it wasn't that bad. Too small of duct will choke the airflow.
Yes, I would aim the registers at an angle towards to floor.

 

[fitter30]

Steel Spiral Supply Curved Grilles, Direct to Duct - IERA - Metallic G

Double deflection steel grid for air injection with individually adjustable straight ns, vertical to the front and horizontal rear. The grid face is curved to adjust to the diameter of the duct. Includes fasteners for xing, deflector, and seal on the frame to prevent air leaks.

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