What Size Register For 6 Inch Duct

Greetings.

Does the Manual D requite annals size with consideration to co-operative size?

Case would be if a room requires 100 cfm using a 6" branch, does that mean that the standard 6x12 register will piece of work. Exercise registers tend to be oversized from the duct to compensate for two-way, three-mode or even four-manner openings?

My question stems from our system. The bedrooms are fed with 6" flex to a 6x12 three-fashion register with closing louvers. They were noisy. I removed them and it'southward very placidity. Well, less than with them installed. And then mayhap an 8x14 or 12x12 would allow the air to dump equally well every bit the 6x12 with no register.

This isn't meant to audio similar a DIY. Just looking for noesis. I'g going to get a Manual J & D performed. Need to know what to wait from the D and if there is notwithstanding room for improvement at a personal level.

Registers have zero to do with co-operative size. The supply grille is sized for noise [mostly] and pressure drib. You lot desire a NC of under 20.

Your reply is my point. If the room takes a 6" drop, the register is unremarkably the standard 6x12. Does the Manual D address this?
What does NC correspond.

Quote Originally Posted past hvacconsultant View Post

Registers have naught to do with co-operative size. The supply grille is sized for noise [mostly] and pressure drop. Yous desire a NC of under twenty.

Supply grilles are sized for throw and spread with a velocity that volition meet adequate noise levels. Manual T is the guidance document for air distribution. One of the problems with most duct systems is they are but sized for noise and force per unit area, and the power of given registers to distribute the air correctly to meet comfort level are ignored.

When I accept the Transmission D performed for our firm, volition it address the register size? Sounds similar there is even so an other manual, Manual T?

Quote Originally Posted by regis101 View Post

When I take the Manual D performed for our house, will it accost the register size? Sounds similar there is yet an other manual, Manual T?

Diffusers are rated to a ( NC ) Noise Criteria past the manufacturer.
i.e.
http://www.titus-hvac.com/ecatalog/g...spx?fileid=898

... < two CFM / Sq In (300 CFM / Sq ft) should exist quiet
IF installed properly.

Nice link. Expert info.

Does the Transmission D give annals size? Seems to be a vital office of the equation. Seems senseless to have it done if the registers are non incorporated. What about in the cease, the register ends upwardly noisy. Tin can I go bigger and still be happy?

It is a simple fact of life that there is a world of difference between a pattern built residential system and a mechanically engineered commercial/industrial job. With the latter, these is a blueprint that lays out the system including all duct sizes and supply outlets. CFM delivery is required and at some time during the commissioning procedure the entire system is menses hood balanced to design specifications. This attention to item does of class, come at a price. Hence the essentially higher costs for an engineered job. Just that doesn't leave the residential customer necessarily pain.

A high quality visitor at the residential end will do a Manual 'J' load assay, a Manual 'D' duct design and use the register/diffuser/grille manufactuer'southward applied science numbers to deliver the proper results of both dissonance, CFM delivery and balance. Whatsoever experienced HVAC company knows pretty closely what the static pressure will be in his designed system. That by default should dictate how many and what size supply outlets demand to be installed in a room. Equally to branch duct size, that's a office of the velocity. Over again, deferring to noise, a good company will design for low noise. All of this must take into consideration the actual installation. Our company issues it'south installers a 'cheat canvas' that contains engineering data taken from our favorite diffuser manufacturer, using the sizes and CFM commitment closest to the anticipated static force per unit area we will see in the finished arrangement. It's a relatively simply affair to adjust volume dampers in each supply branch to bring whatsoever errant residuum problems under control but quite honestly, when done to the numbers, we have precious few trips out with the menses hood for balancing purposes.

07:53 PM

Quote Originally Posted by skippedover View Post

It is a simple fact of life that there is a world of divergence between a design built residential system and a mechanically engineered commercial/industrial job. With the latter, these is a blueprint that lays out the system including all duct sizes and supply outlets. CFM delivery is required and at some time during the commissioning process the unabridged system is flow hood counterbalanced to design specifications. This attending to detail does of course, come at a price. Hence the substantially higher costs for an engineered job. Merely that doesn't leave the residential customer necessarily hurting.

A high quality company at the residential stop will practice a Manual 'J' load analysis, a Manual 'D' duct design and utilize the register/diffuser/grille manufactuer'south technology numbers to deliver the proper results of both noise, CFM delivery and residuum. Any experienced HVAC company knows pretty closely what the static pressure level volition be in his designed system. That by default should dictate how many and what size supply outlets need to be installed in a room. As to branch duct size, that's a office of the velocity. Again, deferring to noise, a good company volition design for low noise. All of this must have into consideration the actual installation. Our visitor issues it's installers a 'cheat sheet' that contains engineering data taken from our favorite diffuser manufacturer, using the sizes and CFM delivery closest to the anticipated static pressure we will see in the finished organization. It's a relatively merely matter to accommodate book dampers in each supply co-operative to bring any errant balance bug under control but quite honestly, when done to the numbers, we take precious few trips out with the catamenia hood for balancing purposes.

Pretty much they WAY It SHOULD Exist.

Your grilles may exist the incorrect type,since they are noisey.

Well that was a large circle, huh. I see the hoods all the time at work. I curve an heart to run into them calculating, closing or opening the damper and moving on to the next.

I only want and need to be assured that when I rent someone to plug in the numbers I give them that the human fault gene is nil.

Nearly of the powers that exist around here insist on having systems washed using the Manuals. To this I concur. To this I volition also have the duct designed. Hopefully the human factor is lessened due to the program. Hopefully the human factor is heightened to bring me, John Q Public, the results that we're paying for. I hate paying for stuff and all the same take questions.

You can read up on my dilema by searching in "Threads Started" in my profile

Programs don't eliminate humn error ,I call back they really can increase information technology.Just don't let that be a reason non to take the calcs done!!!

I am having the calc's done. Sending off the paperwork tomorrow. I emailed the designer to ask about registers. He said that it'll be addressed. Also said most would but slap any 'ol thang on there.

Whew. Close ane

Regarding nuance'south post #9, I hold that they are beasts of a different brute.

The commercial side, of loftier rises at least, employ dampers at every driblet. They become their supply from a common shaft. Unused air ends up back in the system. Correct me at that place where I'm incorrect

Residential has the same air circulating in a closed loop. I would recollect the design for them would utilise no dampers. Each room has it'south own requirement and open areas with multiple registers work in conjunction, Information technology seems that the system should self-rest. Another wrench thrown in is when a 2nd story is involved.

I'm hoping the Transmission J & D with consideration of T that I'm paying for answers all my questions. Otherwise I'll accept to purchase a PC and do'er me dern cocky.

You lot nevertheless have dampers in your residential organization, or at least you should. I do in my home and the ductwork was in that location before I was born. Sure all of the air that gets supplied will be returned but y'all need that air to go where information technology is supposed to. A lot of cheap builders volition have just a single return grille located in the eye of the abode without individual returns. The systems mostly don't work that well.

In a commercial building you should take a damper in every branch of the ductwork so it can exist counterbalanced. Most aren't or not correctly balanced, but that is another argument. You don't take air circulating in a airtight loop. Ordinarily they are VAV with pressure sensors backing the main supply fan down equally the VAV box dampers close. I accept seen and used a airtight loop supply duct, but it is intended to human activity equally basically two supply runs with a signal of equal pressure level as the boundary betwixt the two. I personally don't similar that design since it doesn't usually behave as it is supposed to.

I'll have to wait and see what the Manuals work out.

My house is mainly 36x25 with a 10x17 room that would make the house shape as an "L". 1070 sq ft of inside living space. The iii ton unit appears to be oversized and the duct piece of work too small. Have to outset all over, maybe.

Quote Originally Posted past regis101 View Post

I simply desire and need to be assured that when I hire someone to plug in the numbers I give them that the human mistake cistron is nil.
.. done using the Manuals.
.. To this I volition likewise have the duct designed.
.. I hate paying for stuff and still have questions.
You can read up on my dilema past searching in "Threads Started" in my profile

Ship me (e-mail in my profile)
your house plans & orientation,
window sizes & specs,
r-value or walls and ceiling,
Thermostat set signal,
Mfg and model number of condenser and air handler.

If Y'all know these building envelope parameters,
the variation due Homo Factor judgment is cipher.

I let you know CFM required per room and diffuser sizes based on
Transmission J 8th edition, Titus itemize for < NC twenty.

Guesstimating
1,070 Sq. Ft.
2- ton .. 800 CFM
seems like there mayhap 7 rooms > 100 Sq. Ft

i.due east. xv x 15 room = 225 Sq. Ft might need ~ 170 CFM
__. ten x 17 room = 170 Sq. Ft might need ~ 140 CFM
__. ten x eleven room = 110 Sq. Ft might demand _~ 80 CFM

You're non probable to have more than one room requiring > 150 CFM,
unless there is a large window/ drinking glass door area.
If you have > 160 Sq feet of windows and drinking glass doors,
a 2-ton may unit be besides small.

8" diameter duct will handle ~ 200 CFM.
Then co-operative max size would probable exist viii".

i,070 Sq. Ft should be anything BUT circuitous.

Merry Christmas