Fundamentals Basic Selection and Application
Transcript of Fundamentals Basic Selection and Application
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Basic Selection & Proper Application
of Overhead Air Distribution Devices
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GRD Selection & Application
• Terms
• Selection
– Throw – Sound
• Installation Variations affect Performance
• Inlet Effects
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Basics
Coanda
Total
Air
Primary Air
Induced
Room Air
Entrained
Room Air
Return Air
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Basics
• ASHRAE Standard 70-2006
– Standard Defines Testing Procedures,
Spaces, and Equipment
– Isothermal Testing
– Non-Turbulent, Smooth Inlet Conditions
– Obtain Catalog Data
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Selection – Throw
1) Throw – Distance to a specified Vt
2) Terminal Velocity (Vt) – Maximum
airstream velocity at the end of a throw.
50 fpm TV
100 fpm TV150 fpm TV
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Selection – Throw
• Outlet Patterns – 150 cfm – 6” Inlet
Plaque- 6’
Slot - 19’ Slot - 29’
Perf - 10’Louver
Face - 16’
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Selection – Throw
• 380 cfm, 10” Neck, 700 fpm, T50
10‟ Square Cone
9‟ Round Cone
14‟ 4 Way - Perf Curved Vane
33‟ 1 Way - Perf Curved Vane
24‟ 4 Way - Louver Face
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Selection – Throw
• Deflection and Spread
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Selection – Throw
• Throw Boundaries – Mapping
Vt Maximum of 75 fpm
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Selection – Throw
• Occupied Zone
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Selection – Throw
• Generally:Throw (Vt at 50 fpm) = Distance to Boundary
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Selection – Throw
• Non-Isothermal Effects
Adjust Throw at V t = 50 fpm
1% Per° F of Differential
Cooling Heating
Horizontal – +
Vertical + –
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Selection – Throw
• Obstructions
– Air jet will typically remain on surface, if angle
created by the ceiling, diffuser, and bottom of
obstruction is
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Selection – Sound
• Catalog Data
– NC Rating
• Average Room Size
• Distance from Source
– Assumes 10 dB Room Absorption
– Single Diffuser or Standard Length
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Selection – Sound
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Selection – Sound
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Selection – Sound
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24” x 24” Diffuser, 380cfm, 700 fpm Neck Velocity
3-21
Selection – Sound
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NC 45
3-22
Selection – Sound
NC 37
NC 36NC 31
1 - 1”Slot, 4‟, 270cfm, 800 fpm Neck Velocity
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3-23
Installation – Sound
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Damper Location
Pressure Ratio = 2
(normal pressure
drop X 2)
3-26
Installation – Sound
0 dB
+ 3 dB
+ 9 dB
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Inlet Effects
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ASHRAE Standard 70 – Throw Room
• Measurements taken in a „Standard Test Room‟
– Height => 9‟
– Minimum Length = 24‟
– Minimum Width = 18‟
– All lights and windows shall be flush to the surface they
are attached.
– Air exhausted away from supply path.
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• 2 Different Types of Test Ducts
– Large Pressurized plenum
– 3 Diameters Straight duct• Air outlet device is to receive uniformly
distributed air from the supply duct.
ASHRAE Standard 70 – Inlet Conditions
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Effect of Inlet Conditions on Throw
• Test Standard Installation
– Repeatable, uniform throw distances
– Repeatable, drop
– Repeatable, discharge pattern
• Hard 90 Degree Elbow
• Flex Duct 90 Degree Elbow
• Radial Opposed Blade Damper • Butterfly Damper
• Bowtie Damper
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A “Special” Field Installation
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More Poor Workmanship Examples
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Louver Face Ceiling Diffuser
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Louver Face Ceiling Diffuser
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Louver Face Ceiling Diffuser
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Louver Face Ceiling Diffuser - Hard 90 Degree Elbow
350 CFM
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Louver Face Ceiling Diffuser - Flex Duct 90 Degree Elbow
350 CFM
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AHHHH!! FLEX MONSTER!!
Louver Face Ceiling Diffuser
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Louver Face Ceiling Diffuser - Radial Opposed Blade Damper
350 CFM – Damper set for 0.25 inches of water
Louver Face Ceiling Diffuser
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Louver Face Ceiling Diffuser -Butterfly Damper
350 CFM – Damper set for 0.25 inches of water
L F C ili Diff
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Louver Face Ceiling Diffuser -Bowtie Damper
350 CFM – Damper set for 0.25 inches of water
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More Poor Workmanship Examples
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Plaque Ceiling Diffuser
C ff
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Plaque Ceiling Diffuser
Pl C ili Diff
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Plaque Ceiling Diffuser
Plaque Ceiling Diffuser
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Plaque Ceiling Diffuser - Test Standard Installation
350 CFM
Plaque Ceiling Diffuser
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Plaque Ceiling Diffuser - Hard 90 Degree Elbow
350 CFM
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Plaque Ceiling Diffuser
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Plaque Ceiling Diffuser - Radial Opposed Blade Damper
350 CFM – Damper set for 0.25 inches of water
Plaque Ceiling Diffuser
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Plaque Ceiling Diffuser - Butterfly Damper
350 CFM – Damper set for 0.25 inches of water
Plaque Ceiling Diffuser
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Plaque Ceiling Diffuser - Bowtie Damper
350 CFM – Damper set for 0.25 inches of water
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Ceiling Slot Diffuser
Square Plenum
Sloped Plenum
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Ceiling Slot Diffuser
Ceiling Slot Diffuser
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Ceiling Slot Diffuser
- Test Standard Installation
350 CFM with straight plenum
350 CFM with sloped plenum
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Ceiling Slot Diffuser
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g- Flex Duct 90 Degree Elbow
350 CFM with straight plenum
350 CFM with sloped plenum
Ceiling Slot Diffuser
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Ceiling Slot Diffuser- Radial Opposed Blade Damper
350 CFM with straight plenum (dpr set to .25inWC)
350 CFM with sloped plenum
(dpr set to .25inWC)
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C ili Sl t Diff
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Ceiling Slot Diffuser- Bowtie Damper
350 CFM with straight plenum (dpr set to .25inWC)
350 CFM with sloped plenum(dpr set to .25inWC)
W k hi C t !
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Workmanship Counts!
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Sidewall Grille Video (12X6)
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Sidewall Grille Video (12X6)
0 Dia 1 Dia
2 Dia 3 Dia
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GRD Selection & Application
• Terms
• Selection
– Throw
– Sound
• Installation Variations affect Performance
• Inlet Effects