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Air Testing ,Adjusting & Balancing.

A-System Preparation :1-Obtain updated construction drawings ,specifications,approved shop drawings.

2-Prepare field data forms to record testing and balancing process.

3-Obtain system leakage rate data where duct leak testing specfied.

-!erify that fresh air intake type units fan are installed, rotating correctly,controlled to supply the

re"uired airflow rate .#-$heck for clean filters.

%-!olume control dampers are operable, accessible,and are in an open or normal position.

&-$ontrols are operable and calibrated.

'-(o)es are installed,operable and accessible.

B-System Testing And Adjusting.1-*ecord nameplate data on fan ,motor,and fresh air intake type unit .

2-+est and record the fan rpm to cofirm rated speed.

3-easure and record motor running amperes and voltages.

-et system in the minimum outdoor air mode ,then perform a pitot tube velocity traverse of main

ducts and adust fan speeds for total design supply and return air flow rates .+otal design flow mustinclude estimated duct leakage #/ of system total to allow for balancing effects.

#-inimum outdoor air "uantities must be maintained during all system modes.

+he following steps % through 0 occur after all bo)es and related terminals are balanced.

%-easure and record the static pressure resistance of the duct system and static pressure drop

across coils ,filters etc,in the cabinet or out in the duct system.

&-easure and record the pressures at fan suction and discharge per the pressure rating re"uired

,either static or total.

'-+est the system in the ma)imum outdoor air mode .f motor overloads or airflow rates are

e)cessive ,adust fan rpm to suit.

0-easure and record outdoor ,return ,and supply air temperatures with the system set at minimum

outdoor air mode.

C-System Balancing.fter the air system has been prepared according to balance by the procedures set forth in the

following subsections.

hen system characteristic prevent design flow rates balance the system components to e"ual

percentages of design.

1-(alancing ub-ain ir 4ucts.

1a-Perform a Pitot tube velocity traverse of each sub-main duct to determine flow rate througheach.

1b-dust the main volume control dampers to provide the re"uired flow through each sub-main air

duct.

2-(alancing (ranch ir 4ucts.

1a-(eginning at the sub-main duct closest to the fan or with the highest percantage of re"uired flow

, perform a pitot tube velocity traverse of each branch on that sub-main duct run.

2a-Proceeding from the branch with the highest percantage of re"uired flow ,adust the branch

volume control dampers to provide the re"uired flow through each branch duct.

3a-Proceed to the sub-main duct with the ne)t highest percentage of re"uired flow ,traverse ,and

adust each branch per previous steps 1 and 2.a-$ontinue until all branches are balanced.

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3-(alancing ir +erminal 5low *ates.

fter obtaining the re"uired airflow rates in sub-main and branch ducts ,then balance each air

terminal by the following procedure.

3a-(eginning with the branch nearest the fan or with the highest percantage of re"uired flow

,measure the airflow at each terminal on the branch.

3b-tarting at the air terminal with the highest percantage of design flow and ending with the air

terminal having the lowest percantage of design flow ,adust the runout or terminal volume control

damper to provide an airflow rate within 16/ design.

3c-f balance without e)cess pressure has been attained then at least one air terminal on each

branch should have the volume control damper full open .(ranch dampers may re"uire

readustment.

3d-*epeat steps 1 and 2 for the branch that has the ne)t highest percentage of re"uired airflow.

3e-$ontinue until all air terminals are balanced to within 16 / of design.

-5inal dusting nd (alancing.

a-easure and record the final airflow rates at each air terminal.f it is necessary to adust the

airflow rate through a terminal by # / or less ,in order to achieve the final setting within 16 / of

design then it is not necessary to adust nearby terminals which have been final measured.

Otherwise nearby terminals should be remeasured and adusted accordingly if re"uired.b-ecure ,mark.seal and record the final setting position of all volume control dampers installed in

submain or branch ducts.

c-easure and record the final airflow rate at velocity traverses in main ,sub-main and branch

ducts .4o not adust related volume control dampers.

d-easure and record the data re"uired as follows,

d1-+est and record the fan rpm to cofirm rated speed.

-easure and record motor running amperes and voltages.

-easure and record the static pressure resistance of the duct system and static pressure drop

across coils ,filters etc,in the cabinet or out in the duct system.

-easure and record the pressures at fan suction and discharge per the pressure rating

re"uired ,either static or total. -easure and record outdoor ,return ,and supply air temperatures with the system set at

minimum outdoor air mode.

e-*eset all controls for normal operations.