View Full Version : Restrictive supply registers
02-19-2007, 10:55 AM
Recently I removed some of my supply registers (located on second story ceiling w/ duct work in attic) in order to paint the ceiling. The air handler fan was running and I noticed that it seemed like I had a lot more air flow without the register in place. They are 10x6 (fed by 6 inch flex) stamped steel two-way with multiple closing vanes.
Are these registers considered to be excessively restrictive? If so, is there a replacement that I should consider?
Depends on the actual brand ,type/model,some are more restrcitive then others.
Check here for ones that closely resemble what you have,even though yours may be a different brand.
Post the number here to find out how restrictive ,or you can find that on the website also.
02-19-2007, 12:04 PM
Thanks, but I couldn't find anything that appeared close enough. Here is a link that is pretty close except mine are two-way instead of the one-way as shown in the link.
They don't show the specs.,PD(pressure drop).
Here's Hart&Cooley,all 10X6
1.)#661 1/3" blade spacing fixed @20° angle,125 cfm @.016 PD
2.)#682 1/2" blade spacing fixed @40° angle,95 cfm @.016 PD
3.)#612 Curved adjustable blades,100 cfm @.016 PD
The 20° angle is less restrictive ,but might blow more directly down on occupants depending on placement in the ceiling.
The curved blade is the PD for them being adjusted to keep the air flow parallel to the ceing.If adjusted more downward the PD would drop.
I picked the above ,with a common PD,as a common cfm wasn't in the table.I think you can see iwhen the PD is the same,more cfms(cubic feet per minute),shows that one is less restrictive.
One other tip,while there are down,caulk the metal box to the drywall,if there are any gaps.These gaps can account for up to 10% duct leakage if they are large gaps.
Hope this helps.
02-19-2007, 06:07 PM
Many thanks. Yes, it looks like 661 is significanly less restrictive. Unfortunately, what we don't know is how it compares to what I have. I guess the only way to find out is to install one and see how it compares.
And thanks for the tip on closing up any holes. I in fact did find some and plan on pulling the others to make sure they are sealed up.
And, yes - it helps alot.
You should be able to compare the spacing and the set angle of the fins,with what you have.
Where are the grilles located?
02-19-2007, 10:05 PM
Located on the ceilings.
Located on the ceilings.
Near inside or outside walls?
02-20-2007, 08:20 AM
Oh, now I understand what you wanted to know. I'm a little slow.
They are on the ceiling over windows and near outside walls when there isn't a window. Since they are two way they do not wash the window or wall with the throw, but rather direct it down (probably about a 30 degree angle) and parallel to the outside wall.
I have looked at other supply grills on the H&C site and I think the 631 would do a better job of washing the window/outside wall and it has a strong 140 cfm at .016 PD.
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