Method Statement for HVAC Air Balancing and Air Flow Measurement

Table of Content

1. INTRODUCTION

2. PREREQUISITES TO PROCEDURE

2.1 Access / Egress

2.2 Responsibilities / Supervision

2.3 Requirements

2.4 Personal Protective Equipment

3. DESIGN PERAMETERS

3.1 Specification Reference

3.2 Drawing Reference

4. REFERENCE DOCUMENTS

4.1 Relevant Commissioning Codes

5. PRE-COMMISSIONING / PRE START CHECKS

5.1 Static Checks

6. COMMISSIONING / TEST PROCEDURES

6.1 Starting the Unit

6.2 Air Balancing

6.3 Performance Testing

7. DOCUMENTATION

7.1 Commissioning Test Sheets

7.2 Supporting Documentation

8. DEMONSTRATION PROCEDURES

9. INSTRUMENTATION

9.1 Air Flow Rate Measurement

9.2 Performance Testing

9.3 Electrical

9.4 Calibration

10. SAFETY REQUIREMENTS

10.1 Safety Rules during Testing

10.2 Safety/Task Lighting

10.3 Emergency Arrangements

11. ATTACHMENTS

1. INTRODUCTION

1.1 Scope of Work

1.1.1 This method statement covers the air balancing, air flow measurement. Scope of work includes the system start-up operation (to be carried out by the Supplier with the attendance of the commissioning engineer), the physical testing and balancing of the system, the production of the final testing and balancing report and finally the system performance test report.

1.1.2 A survey will be made of the systems installation for damage, obvious defects and, if required, a defect report will be issued to the MEP contractor for rectification

1.1.3 A survey of the ceiling void will be made to ensure access requirements to dampers, test points etc. for the testing requirements.

1.1.4 The aim of the commissioning process is to ensure the design requirements of the systems are achieved during the normal operation of the system.

2 PREREQUISITES TO PROCEDURE

2.1 Access / Egress

2.1.1 Safe access and egress at all times to the location of the FAHU/AHU, the areas the system serves and above ceilings as required is to be provided by the civil main Contractor.

2.2 Responsibilities / Supervision

2.2.1 Commissioning Manager; will have the overall responsibility for the execution of the Testing and Commissioning activities, quality and safety as per the specification and standards. The Commissioning Manager will maintain the planning progress and coordination works with the MEP Project Manager or his nominated representative.

2.2.2 Commissioning Engineer; will be responsible for the day to day activities on site, for the test report and design information approval and the onsite testing and balancing.

2.2.3 TAB technician; will be responsible for the day to day systems balancing at site as instructed by the Commissioning Engineer.

2.3 Requirements

2.3.1 Full set of approved installation drawings, system schematics and specification detailing all systems to be commissioned.

2.3.2 Full set of approved schedules of plant items.

2.3.3 Control system logic and sequence of operation.

2.3.4 All electrical commissioning of MCC, isolators and other electrical equipment pertaining to the system under test to be completed, witnessed and approved.

2.3.5 The system duct work to have been cleaned internally and externally by the MEP Contractor.

2.4 Personal Protective Equipment

2.4.1 All personnel will wear safety shoes, helmet and coverall as described in the Risk Assessment form.

3 DESIGN PERAMETERS

3.1 Specification Reference

3.1.1 The commissioning engineer shall balance the system to the requirements and tolerances as specified in paragraph AA3.4 and table A1 (tolerances for regulation of air flow) of C.I.B.S.E. commissioning code “A”.

3.2 Drawing Reference

3.2.1 Design air flow rates shall be taken from the approved installation drawings and schematics.

4 REFERENCE DOCUMENTS

4.1 Relevant Commissioning Codes

4.1.1 The systems will be commissioned as per the procedure stated in C.I.B.S.E. commissioning Code “A” – Air Distribution Systems and BSRIA application guide AG 3/89.3 – Commissioning Air Systems

5 PRE-COMMISSIONING / PRE START CHECKS

5.1 Static Checks

5.1.1 Installation Complete: MEP subcontractor is responsible for completing the installation works to the approved installation drawings and project mechanical HVAC specifications.

Commissioning engineer shall prepare System Check Sheets for the Installation Contractors use, to highlight the stage of completion the system must be in prior to implementation of commissioning, i.e., preparation of the system for commissioning.

Check Lists relevant to the hvac testing shall be issued for inclusion in the Operation and Maintenance Manuals.

5.1.2 System Check Sheet; the System Check Sheet will be completed by the commissioning agency site engineer, and any discrepancies found shall be highlighted to the Installation Contractor for necessary compliance.

5.1.3 Static checks; the commissioning engineer will carry out and document the following system static checks:

5.1.3.1 Open all grille opposed blade dampers.

5.1.3.2 Open all duct volume control dampers.

5.1.3.3 Mechanically disconnect motorized dampers and ensure dampers move freely, reconnect the actuator and leave in the fully open position.

5.1.3.4 Check all fire dampers are open.Method Statement for HVAC Air Balancing and Air Flow Measurement

5.1.3.5 Open all access panels and inspect system for debris.

5.1.3.6 Visually inspect ductwork where possible.

5.1.3.7 Ensure all flexible connections are air-tight.

5.1.3.8 Open all AHU access panels and inspect the unit for debris or damage.

5.1.3.9 Remove any transit bolts from the motor or fan.

5.1.3.10 Ensure the fan turns freely and check motor and fan bearings.

5.1.3.11 Check pulley alignment and belt tension.

5.1.3.12 Check filters and coils for damage.

5.1.3.13 Check motor name plate and compare with specification.

5.1.3.14 Set motor overload protection relay to full load current as stated on the name plate. If the motor is controlled via a variable frequency drive (VFD) ensure the VFD has been tested and commissioned by the supplier and the commissioning report is available for inspection.

5.1.3.15 Check wiring connections at the motor and control panel.

5.1.3.16 Check power is available on all phases and voltage supplied (415 v or 240 v).

5.1.3.17 Check the Controls Engineer has completed his commissioning of the controls systems.

6. COMMISSIONING / TEST PROCEDURES

6.1 Starting the Unit

6.1.1. Motor No Load Test; the commissioning engineer will carry out the following motor no load checks:

6.1.1.1  Disconnect the belts from the motor and fan.

6.1.1.2 Attach a clip on Amp Meter in the control panel ready to measure the running current (unless controlled via VFD refer to 6.1.4. and 6.1.5).

6.1.1.3 If the control panel is remote from the air handling unit, position someone at the local isolator for the unit.

6.1.1.4 Keep an eye on the Amp Meter, start the unit. If the motor is controlled via a VFD gradually increase the frequency drive to 50 Hz and monitor the motor current.

6.1.1.5 Switch the unit off immediately if:-

The running current is higher than the F.L.C.

The air handling unit is making excessive or unusual noise.

The motor rotation is not correct.

6.1.1.6 Check the motor speed using a tachometer and compare this with the motor name plate.

6.1.1.7 Replace the belts and check for correct tension. Replace all guards inside the AHU.

6.1.2 Starting the Unit; the commissioning engineer will start the unit as per the following procedures.

6.1.2.1 Close the main volume control damper fully (unless controlled via VFD refer to 6.1.2.4. and 6.1.2.5).

6.1.2.2 Attach a clip on Amp Meter in the control panel ready to measure the running current.

6.1.2.3 If the control panel is remote from the air handling unit, position someone at the local isolator for the unit.

6.1.2.4 Keep an eye on the Amp Meter, start the unit.

If the motor is controlled via a VFD gradually increase the frequency drive to 50 Hz and monitor the motor current.

6.1.2.5 Switch the unit off immediately if:-

The running current is higher than the F.L.C. (after starting current has dropped).

The air handling unit is making excessive or unusual noise.

6.1.2.6 If the system performs normally, open up the main volume control damper slowly.

Check the running amps constantly while the V.C.D. is being opened.

Open the V.C.D. until full load current is reached or the damper is fully open.

If full load current is reached before the damper is fully open (or before the frequency is at 50z – set the VFD to the maximum frequency allowed by the motor current as per the manufactures procedures) fix the damper in this position and under no circumstances open further.

6.2 Air Balancing Procedure

6.2.1 Static Checks

6.2.1.1 Check all items in the Test Sheets and record the results.

6.2.1.2 The sequence of work will be as laid out in C.I.B.S.E. Code Series A, paragraph A2.0, and be made available for witness.

6.2.2 Proportional Air Balance

  • Carry out and record an initial scan of all terminals.
  • Analyze the initial scan and identify index terminal and branch
  • Lowest % of design is a logical index
  • Regulate terminal 2nd farthest from the fan to equal % of index
  • Repeat operation on successive terminals working back towards the fan comparing with the index
  • When branch damper is reached, all terminals on the branch are now in balance
  • When all branches are balanced , recheck index terminal on each branch
  • Balance each branch index terminal using branch dampers
  • Check system total volume rate is within specified tolerance
  • Carry out and record a full scan of system. This should show all terminals in balance within specified tolerance
  • Carry out and record a full fan test
  • Mark all dampers. Set terminal air diffusion patterns

6.2.3 Controls Commissioning

6.2.3.1 It will be required for coordination between the Controls Engineer and the Commissioning Engineer to produce the program for the controls commissioning.

6.2.3.2 It will be the responsibility of the Controls Engineer to complete commissioning.

6.2.3.3 It will be the responsibility of the Commissioning Engineer to witness the commissioning and obtain the appropriate commissioning documents to ensure the equipment operates as per the design.

6.2.4 Final Air Balance

6.2.4.1 Site commissioning Engineer will complete the final air balance in accordance with C.I.B.S.E. Code Series A, paragraph A3, and the design figures in the Client’s specification.

6.2.4.2  Test Sheets will be completed up and all figures will be made available the Client’s representatives for witness.

6.2.5 Final Handover of System

6.2.5.1 Commissioning contractor will provide to the client a completed Commissioning Dossier.

6.2.5.2 Any part of the Dossier shall be made available to the Consultant for verification and witness.

6.3 Performance Testing

6.3.1 When the air balancing, the chilled water balancing and the controls commissioning are complete and accepted by the client/consultant, commissioning engineer will carry performance tests on commissioned systems.  This work will include heat wheel performance tests, humidity tests, on-off coil temperatures, space temperature readings and noise level tests, in accordance with C.I.B.S.E. Code Series A, and the current client specifications.

6.3.2 The performance test sheets will be completed by the commissioning engineer and made available to the Consultant for witness.

7. DOCUMENTATION

7.1 Commissioning Test Sheets

7.1.1 The testing and commissioning results will be documented on the following test formats:

  • AHU Pre commissioning Sheet
  • AHU Performance Sheet
  • Air Balance Terminals
  • Air Balance Traverse
  • Commissioning Certificate
  • Data Sheet
  • Static Civil Check List
  • Installation Contractors Air Distribution System Check Sheet

7.2 Supporting Documentation

7.2.1 The following supporting documents will be issued along with the testing and commissioning report:

7.2.1.1 Schematic drawing indicating all test point locations.

7.2.1.2 Valid calibration certificated for the instruments used for the testing and commissioning of the system.

8. DEMONSTRATION PROCEDURES

The commissioning engineer will ensure that the following works are carried out:

8.1 The final tested and balanced results are demonstrated to the accepting authority on a random spot check basis, and that repeatability of readings is proven within the accepted tolerance.

8.2 Submittal of all records of data obtained during testing, adjusting and balancing in accordance with, and on, the approved forms.

8.3 Preparation of report of recommendations for correcting any unsatisfactory mechanical performances when system cannot be successfully balanced.

9. INSTRUMENTATION

The following test instruments will be used for the commissioning and testing activities.

These will be selected as having the maximum field measuring accuracy and being the best suited to the function being measured, and will be applied as recommended by the manufacturer.

9.1 Air Flow Rate Measurement

9.1.1 Vane anemometer

9.1.2 Balometer

9.1.3 Micro manometer

9.2 Performance Testing

9.1.1 Plant speeds – tachometer.

9.1.3 Sound Level meter

9.3 Electrical

9.3.1 Clip-on ammeter

9.4 Calibration

9.4.1 All instruments used will carry valid calibration certificates or certificates of conformance to the tolerances specified in the referenced standards.

9.4.2 Sufficient calibrated instruments will be provided by commissioning contractor as required to meet the program schedules.

9.4.2 Instruments will be properly maintained and protected against damage.

9.4.3 Calibration periods for all instruments are as recommended by the instrument manufacturers and are in line with the requirements of the Commissioning Specialists Association.

9.4.4 Certificates will be available for presentation prior to commencement of the works.

10. SAFETY REQUIREMENTS

Health and Safety procedures by all parties will be implemented for this job. The responsible safety officer as per procedure will conduct a routine safety inspection.

10.1 Safety Rules during Testing:

In order to ensure safe conditions during testing the following rules have to be followed:

10.1.1 Persons engaged with inspection and testing have to be skilled and have received proper and adequate training related to procedures and test equipment utilized for the particular testing activity.

10.1.2 Test instruments and test leads should be maintained in a safe condition and the test methods not to create danger either for the operator or for other persons or livestock.

10.1.3 Where tests are required to circuits which are live for amp readings then the tightness of the cable terminations will be checked without power prior to live amp readings

10.1.4 Ensure that warning labels are installed on MCC’s and plant.

10.1.5 When readings are being taken for amperage and running speeds a support engineer will be in attendance for safety reasons.

10.2 Safety/Task Lighting

10.2.1 Safety lights will be used in case of power failure ensuring the good illumination of the working area to aid evacuation if necessary.

10.2.2 Adequate lighting shall be provided to ensure the good illumination on the working area.

10.3 Emergency Arrangements

10.3.1 General:

Site general safety procedures will be followed.

In case of emergency the Safety Officer or the most senior employee present will stop the work, and make the necessary emergency arrangements and report to the assembly points as described during Site Induction Course.

10.3.2 Fire Precautions:

No significant fire risks associated with this activity but general fire precaution measures will be taken as per Main Contractor instructions.

11. ATTACHMENTS

  • AHU Pre commissioning Sheet
  • AHU Performance Sheet
  • Air Balance Terminals
  • Air Balance Traverse
  • Commissioning Certificate
  • Data Sheet
  • Static Civil Check List
  • Installation Contractors Air Distribution System Check Sheet

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