Better check out Manual D, or read following:Originally posted by amickracing
Better air flow, less restriction, hopefully less turbulance thus a better straighter line through the filter causing better filtration.
Oh, and they look cool too :-)
Originally posted by neophytes serendipity
Radius heel elbows at the equipment on the return side do absoluteley nothing for airflow. Equivalent length is exactly the same as a square throat / square heel combo. H/W=1 then that is 45 feet of duct. H/W=2 then that is 30 feet of duct. H= opening at furnace, W= narrow width of drop.
Radius throat ells show little benefit until the throat is 1/2 the diameter of the drop (H/W).
Correctly installed turning vanes are equivalent to 10 feet of duct- same as a radius ratio of 1:1.
Reference velocity of 700 fpm @ .08" WG per 100' of duct. ACCA Manual D page A3-14.
Might as well use square throat / square heel. Cheaper and faster to make than a radius heel.
Or do it right with turning vanes.
You will find that the bottom 1/3 of the filter will get loaded faster on a sysyem without vanes or the proper radius throat because all the air is going there. Filter restriction ratings are based on using the whole filter, not just part of it.
Nice install otherwise.
[Edited by neophytes serendipity on 11-25-2005 at 09:19 AM]
That was my point these elbows ONLY LOOK good they are no better than square throat and heel elbows as stated by N.S. my hope is to encourage better understanding and function. An excellent example of where understanding this particular sheet metal application's shortcomings is where a DX coil is located right after one of these elbows, you will find that you will have the symptoms of low air flow for the refrigeration system but measuring the flow will show the proper amount.