Air distribution through an open duct

[geo44]

I have an architect who is extremely concerned with aesthetics and wants us to provide an open slot duct connection in lieu of a bar type linear diffuser for air distribution, I am well aware of a lack of distribution with this scheme and have informed the architect of the problems that may occur with dumping and stratification of the air. I don't want to agree with something that I know will end up being a source of complaints, in order to somewhat control this I was considering the installation of Young regulators for air balancing and some kind of distribution, any comments would be appreciated

 

[berkshire]

Do you have room to build a plenum chamber behind this slot ?
B.E.

You are judged not by what you know, but by what you can do.

 

[pocketengineer]

Architect is always one kind. Engineer, being another kind, should always insist on technical performance. At the end of the project, it is always the engineer's fault when thing does not work.

When comes to this kind of situation, I would propose frameless slot diffuser for the architect to consider. It is a standard product with control damper, see image attached. Usually, architect just does not want to see the frame of the diffuser. I managed to convince the architect for my projects.

.TT pocketengineer SD
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[SAK9]

Do not accept it.For air distribution you require a proven device with a catalogued performance.Air velocity is important to ensure sufficient induction of room air and to avoid dumping of air at 13C onto occupants

 

[willard3]

You are the Engineer, use a diffuser......proper air distribution is your resp[responsibility.

 

[dbill74]

Best thing I've found when dealing with these type of architect requests is to find several aesthetically pleasing alternatives and present to the architect for him to choose from. This will give him the feeling that he is still driving the design and will be pleased with the looks while you get a system that is functional.

Don't be afraid to explore options beyond different diffusers, consider duct location or even the type of duct. Ductsox is a good alternative.

 

[DrRTU]

Do as we do with long linear grilles, make active and inactive sections. Blank off the section with flat black blank offs and you will have the correct velocity for throw/coverage on the active area. The Arch get his “look” and you get the $ of an expensive system.

 

[lilliput1]

Use linear slot diffuser with one or two slots and adjustable vanes to direct air down at perimeter wall or horizontal across ceiling. Use the linear grille inactive sections as return to hidden above ceiling return air intakes with balancing damper and ceiling access panel. For supply provide supply air plenum sized at 300 FPM. Provide damper supply air branch duct maximum 3' spacing for supply to the plenums. Provide damper in each branch duct with wired operator accessible through the linear grille if ceiling is not accessible.

 

[Drazen]

Few books, Recknagel Hnadbook and Chang HVAC Hanbook offer calculations for open slots, together with some limitations.

Flow and pressure need to be controlled very well at duct entrance. Some obstacles should not exist in space.

And, even more important, you need to charge architect for extra effort in engineering. So, it is possible, but you have to charge it!