Leave blank if NO

Enter a "Y" if YES

Min-cfm Max-cfm Required

Duct Size Amount Total cfm Total Small zone Bypass cfm Round Duct Rectangular Duct

R-6 0 0 0 0 bypass not needed bypass not needed

R-7 0

R-8 0

R-10 0 CFM ROUND

R-12 0 Minimum Maximum

R-14 0 200 300 6"

R-16 0 300 500 7"

8" x 10" 0 400 700 8"

8" x 12" 0 550 1100 10"

8" x 16" 0 800 1600 12"

8" x 20" 0 1100 2100 14"

8" x 30" 0 1600 3000 16"

Total 0 Copyright Arzel Zoning Technology, Inc. 2002 Rev- 2/25/03 jcr

8" X 20" or 10" X 16"

3.25" x 10"

3.25" x 12"

6" x 10"

Arzel Zoning Technology Inc.

Bypass Sizing calculatorA/C Tons

Trunk Dampering?

capacity required See README File.

This sizing calculation is only an estimate of bypass capacity needed, consideration of duct style, equipment location, diffuser style, etc, influences actual bypass

Bypass Duct Size

* If branch ducts are FlexDuct drop to next size smaller bypass

8" X 30", 10" X 20", 12" X 18"

8" X 10" or 6"x 14"

8" X 16" or 10" X 12"

RECTANGLE

Bypass Duct CFM Capacity

Enter Capacity of Cooling Unit in Ton's (over 5 ton multiply by 1.2)

Enter Number of and size of Branch runs in smallest zone

Bypass Calculator will determine size of Bypass Duct needed

Smallest Zone Size

A/C Tonnage Adjusted CFM 5" Round 140 CFM

2 600 6" Round 200 CFM

2.5 750 7" Round 280 CFM

3 900 8" Round 340 CFM

3.5 1050 10" Round or 8" X 10" 550 CFM

4 1200 8" X 12" 600 CFM

5 1500 8" X 14" or 10" X 12" 700 CFM

5 ton w/ branch dampers 300 cfm / ton 12" Round or 8" X 16" 800 CFM

Over 5 Ton 400 cfm / Ton 8" X 20" 1000 CFM

Trunk Dampering 400 cfm / Ton 10" X 20" 1260 CFM

(3) CFM @ Round

1500 to 2000 fpm Metal pipe

300 - 400 6"

400 - 550 7"

550 - 750 8"

750 - 1150 10"

1150 - 1600 12"

1600 - 2100 14"

Dynamics of Air Flow and Zoning

To maintain maximum heat transfer and peak effectivness with the smallest zone calling, we attempt to deliver 200% of design cfm.

To deliver 200% of design cfm, we must increase static pressure by approximatley 400 to 500% .

In most applications the smallest zone can deliver twice the design cfm without air noise issues.

Arzel Zoning Technology, Inc.

Bypass Sizing Chart

What determines bypass need and size ?If the smallest zone moves less than 40% of the total cfm at design static, you might need a bypass duct

If Equipment Size is larger than 5 tons , the blower has the capacity to deliver higher static pressure. (use 400 cfm/ton in step #1)

If Location of smallest zone is very close to equipment and has minimal friction, next size larger bypass might be appropriate

If the smallest zone is far from equipment and has significant friction, you might need to decrease bypass size

If the Size of the smallest zone(sg ft) compared to cfm output at 200% increase is out of balance, it may require larger bypass

Blower performance (cfm output) decreases up to 25% as the static pressure increases.

Bypass air does not provide BTU exchange at equipment and is used soley to eliminate air noise caused by elevated static and velocity.

Velocity incresaes at the open branch runs and decreases at the main trunk and equipment.

Variables that influence Bypass Sizing

When in doubt, call for application assistance1-800-611-8312 / 216-831-6068

(1) Determine Total CFM @ max static pressure

(2) Subtract CFM of smallest zone @ max static pressure

Excessive cfm into a small area might cause overshooting of thermostat set-point

When Trunk Dampering static pressures in open supply duct will increase at a higher rate ( use 400 cfm/ton for total in step #1)

In Flex Duct Applications, it might require higher static to deliver max cfm to the small zone.

(downsizing bypass might be appropriate)

(3) Size Bypass per chart belowRectangle

Metal duct

3.25" X 10"

(3) Size bypass for remaining cfm per chart(1) Approx CFM @ max static pressure (2) Max CFM of smallest zone

Subtract (2) from (1) to find required bypass CFM (3)

8" X 20" or 10" X 16"

When bypassing over 2100 cfm, use two bypass ductsCopyright 2002 by Arzel Zoning Technology, Inc.

3.25" X 12"

8" X 6"

8" X 10"

8" X 16" or 10" X 12"

Min-cfm Max-cfm

Outlet Amount Total cfm Total Small zone Stnd- 5" OD 0 0 0

Slotted .5x8 0

Total 0

CFM

Minimum Maximum

400 600

500 800

700 1000

Copyright Arzel Zoning Technology, Inc. 2002

Smallest Zone Size

This sizing calculation is an estimate of required bypass, consideration of duct style, equipment location, diffuser style, etc, influences actual bypass required

Unico's recommendation when zoning their system is to maintain a minimum of 3 outlets per ton of A/C in each zone

Bypass Calculator will determine size of Bypass Duct needed

Bypass Duct CFM Capacity

Arzel Zoning Technology Inc.

"High Velocity" Bypass Sizing calculator

Enter Capacity of Cooling Unit in Ton's

A/C Tons Enter Number of Outlets in smallest zone

Required

Bypass cfm

0

ROUND

6"

7"

8"

Rev- 3/04/04 jcr

Bypass Duct Size

This sizing calculation is an estimate of required bypass, consideration of duct style, equipment location, diffuser style, etc, influences actual bypass required

Round Duct

bypass not needed

Unico's recommendation when zoning their system is to maintain a minimum of 3 outlets per ton of A/C in each zone

Bypass Calculator will determine size of Bypass Duct needed

Bypass Duct CFM Capacity

Arzel Zoning Technology Inc.

"High Velocity" Bypass Sizing calculator

Enter Capacity of Cooling Unit in Ton's

Enter Number of Outlets in smallest zone

A/C tonnage CFM DUCT SIZE CFM @ 1000fpm

5" Round 140 CFM

2 800 x.75 = 600 6" ROUND 200 CFM

2.5 1000 x.75 = 750 7" ROUND 280 CFM

3 1200 x.75 = 900 8" ROUND 340 CFM

3.5 1400 x.75 = 1050 10" ROUND & 8"X 10" 550 CFM

4 1600 x.75 = 1200 8" X 12" 600 CFM

4.5 1800 x.75 = 1350 8" X 14" - 10"x 12" 700 CFM

5 2000 x.75 = 1500 12" Round & 8" X 16" 800 CFM

8" X 20" 1000 CFM

10" X 20" 1260 CFM

(3) CFM ROUND

1000-1500fpm Barometric

300 to 600 8"

500 to 800 10"

800 to 1200 12"

1100 to 1600 14"

Arzel Zoning Technology

Bypass (Barometric) Sizing Chart Subtract (CFM capacity of smallest zone(2)) from (total cfm x.75(1))

Size bypass for remaining cfm according to chart below (3)

RECTANGLE

Barometric

8" X 12"

(1) Minimum CFM of System (2) CFM Capacity of smallest zone

Subtract (2) from (1) for BYPASS SIZING (3)

Over 5 Ton- Use 400 cfm/ton

400 cfm x .75 = 300 cfm/ton

8" X 12" to 10" x 12"

10" X 12" to 12" x 12"

8" X 20" to 12" X 20"

1054

Bypass sizing factors

Branch dampering vs Trunk dampering

Tonnage divided by total runs damperd

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