Any recommendations on manufacturers of oval duct for HVAC? I’ll work back from manufacturer to any suppliers in my area.
All I’ve been able to find is Standex, supplier for Lowes. Largest oval duct size they have is 3-1/4″x10″ which they label as 8″, I calculate it’s about the same (with area and friction) as 6.5″ round. By same calculations 3-1/4″x12″ oval would give me 7″ round, which is closer to what I want. That would then feed 7″ round duct. Trying to replace a run of (poorly installed) 8″ flex duct with rigid while I have a wall open. Rectangular limits me to equivalent of 6″ round (6.86″ going into reducing round) which seems small for the space (168sf), esp with a lot of twists and turns in the duct run. Also 14″ wide duct requires moving a stud with plaster wall behind it…..
I’m using the formula pi r^2 = 1.55 (ab) 0.625 to compare round and oval, where r is radius of round and a,b are dimensions of oval.
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Any reason you can't use a standard rectaungular wall stack instead of oval. 3-1/4 x 12 will easily fit beween (16" o.c.) standard 2x4 studs and will reasonably pass 100 cfm. By area, the equivalent of 7" round, by friction, nit quite the equivalent but close to 7" round.
As far as amnufacturers; Gray, Champion Furnace Pipe, Snappy (Standex) and Southwark are the ones I know about. I'm sure there's more.
Thanks for the brand name recommendations. I moved that stud that was limiting me to 3-1/4x12 (due to placement of ceiling joists). Plaster wall still standing..... Now I'm limited to 3-1/4x14 duct. With square duct I calculate that to be about equivalent to 6.86" round while oval duct gives me 7.5". Given the duct will make about 10 90-degree turns (I'm counting 2 45s as 1 90) as it weaves between conduit, waste line, water lines and joists, I want to go bigger as much as possible. From looking at online catalogs (mainly for industrial) it looks like I won't be able to do better than 3x14 oval, which is still about 7". I expect I'll bring 8" round to the stop of the wall stack, to increase the pressure as I start the descent...