Self-Balanced Distribution Duct Plenum
Self-Balanced Distribution Duct Plenum
(OP)
This is a little obscure request, but I'm hoping someone out there can point me in the right direction.
I'm trying to design a self balanced air distribution plenum by pressurizing a piece of ductwork and cutting holes of increasing size to deliver the same volume of air to each hole as we travel down the duct.
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I've seen this concept in open spiral duct applications, and fabric duct application, I'm just attempting to translate it to rectangular duct with rectangual openings.
Anyone have a formula, or design guide that would point me in the path to layout the pattern of holes?
I'm trying to design a self balanced air distribution plenum by pressurizing a piece of ductwork and cutting holes of increasing size to deliver the same volume of air to each hole as we travel down the duct.
---------------------
. o 0 O |
---------------------
I've seen this concept in open spiral duct applications, and fabric duct application, I'm just attempting to translate it to rectangular duct with rectangual openings.
Anyone have a formula, or design guide that would point me in the path to layout the pattern of holes?





RE: Self-Balanced Distribution Duct Plenum
RE: Self-Balanced Distribution Duct Plenum
B.E.
RE: Self-Balanced Distribution Duct Plenum
Total pressure changes/decreases along the length, but static pressure stays the same.
RE: Self-Balanced Distribution Duct Plenum
RE: Self-Balanced Distribution Duct Plenum
Willard was right I should have said total pressure, but you figured out what I was trying to say.
B.E.
RE: Self-Balanced Distribution Duct Plenum
RE: Self-Balanced Distribution Duct Plenum
sometimes the air immediately upstream does not like to exit the first holes, likes to blow straight down the duct
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Self-Balanced Distribution Duct Plenum
Isn't that why "sugar scoops" were developed, to stop that?
B.E.
RE: Self-Balanced Distribution Duct Plenum
I was troubleshooting a commercial system once, drilled a hole in supply duct on discharge, blower casing door, return duct. Figured I could check some statics, see what was happening in supply duct, return duct and what it was taking to pull air through the filters/coil.
Got a rediculously low TSP on the fan.
Turns out there was some turbulance on the discharge, was getting a negative supply static, "no cold air" was coming out of the hole I drilled. 2 feet down the line was the discharge air sensor so I pulled that out, got a decent reading, and a correct TSP that jived with what the air balance report on the grilles said and what the fan curve and rpm were saying.
Sometimes air dos not want to do the samething we want it to do.
Take the "V" out of HVAC and you are left with a HAC(k) job.