Method Statement Title: Installation of Fresh Air Handling Units (Floor Mounted)
1.0 Scope
- This method statement applies to the installation of floor mounted air handling units as per the Specification Section 15700.
- Purpose
- Purpose of this method statement is to outline the method of storage and installation of Floor mounted Air Handling Units.
- Material
- Fresh air handling units.
- Pipes and fittings as per approved submittals/drawings.
- Ducting and accessories as per approved submittals/drawings.
- Electrical cables, control panel, other accessories if any, as per approved drawings and submittal.
- Method
- Receiving
- On arrival at site all Air Handling Units (AHUs) shall be checked for quantities, type and model number, physical damages, orientation of coil connections, access doors, etc.
- Upon delivery material on site inspection shall be carried by R&P/NMX/MACE.
- Upon satisfactory inspection the AHUs shall be stored properly with protective covering.
- Preparation
- Check the AHUs foundation and ensure it is as per approved drawings.
- Check the area around the foundation and ensure access to the AHUs from all sides as applicable.
- Ensure availability of sufficient slope to the drainpipe, for easy draining of condensate drain.
- Check the foundation surface and it shall be smooth finish to avoid any dust accumulation.
- The foundation surface shall be even in all directions.
- The foundation surface shall be cleaned before installation of AHUs.
- Mark the AHUs position on the foundation for centralisation.
- Place the anti vibration ribbed rubber pads of correct thickness as per approved drawings/submittals.
- In case of multiple rubber pads the pads shall be placed one above the other, with the ribs at right angle to each other.
- AHU sections are assembled at site/location by factory trained personal.
- Installation
- Shift the AHUs to the place of installation in safe manner using fork lift/crane as applicable. Sufficient manpower will be engaged as required for safe shifting and installation.
- Ensure that the correct AHU is shifted to the place of installation.
- Air inlet, outlet, fresh air connection and chilled water connection orientation are as per approved drawings.
- If the AHUs are shipped in multiple sections, the AHUs will be assembled strictly as per the manufacturer’s instructions.
- Remove the movement arrestors provided inside AHUs at Fan and impeller which are fixed during transportation.
- The AHUs are placed correctly on foundation with vibration isolator rubber pads at right location.
- The AHUs will be properly levelled and parallel to room walls/other installations.
- AHUs shall be inspected again for any damage during hoisting/shifting and installation by R&P/ETA.
- Upon satisfactory positioning of AHUs any open air/water outlets of AHUs shall be closed properly and area shall be cleaned, complete protection in areas where other trades are working.
- Air, Chilled water, Electrical and Condensate Drain connections
- Air side connections
- Ducting connection shall be done as per approved shop drawings.
- Provide flexible duct connections as applicable/as approved submittal.
- Provide proper supports as per approved drawings.
- The weight of ducting shall not act on AHUs panel.
- Before making final connections to AHUs ensure inner area of AHUs is clean, especially the impeller of the fan.
- Chilled Water connections
- Chilled water connections shall be made as per approved drawings.
- Ensure supply and return connection is made properly.
- Provide pipe flexible connection and other piping accessories as per approved drawings and submittals.
- The piping shall be free of any strain and shall not exert any load on, AHUs panel/AHUs.
- Provide vibration isolators to piping supports as per approved submittals/drawings.
- Install the control valves, strainer, commissioning set correctly as per direction of flow as per approved drawings.
- Ensure proper operation of valve handles and sufficient space for valve installation.
- The location and orientation of the gauges and commissioning sets shall allow for easy accessibility and readability of readings.
- Electrical connections
- Electrical power connections shall be done as per approved drawings.
- Cables shall be installed and terminated as per approved method statement Ref;ETA/MS/E/015.
- Condensate drain piping connections
- Condensate drain piping shall be terminated at the nearest floor drain.
- Provide the `U’ trap in the condensate drain piping.
- Ensure provision for cleaning of `U’ traps.
- Ensure proper slope to enable easy draining.
- Ensure trap is deeper than ESP of fan – eg., 70mm > 650pa
- Cleaning
- Clean the interiors of AHUs including the impeller, drain tray.
- After completion of installation, it shall be checked and certified by the supplier/manufacturer and inspected by R&P/ETA.
4.6 Testing
- The piping connections to AHUs shall be pressure tested to 1.5 times the working pressures. Coils not included in test.
- Strainer shall be cleaned after pressure testing and initial flushing of chilled water piping system.
- Flow test of the AHUs drain tray, condensate drain pipe and ensure water is drained out completely.
- Inspection
- Work Inspection Request (WIR) shall be raised for consultant’s inspection.
- QC inspection shall be carried out as per the installation checklist and manufacturer’s instructions.
- Inspection shall be recorded in the approved format and signed off by R&P.
- Safety
- All safety precautions shall be followed as per established project safety plan and procedure.
- Only experienced and skilled technicians shall be engaged for carrying out AHUs installation work.
- The people involved in the installation shall use PPE such as safety helmets, safety shoes, harnesses, gloves, etc as required.
- Safety officer shall check and ensure that all safety precautions are followed.
- Safety officer shall check and ensure that all scaffolding and ladders used at site are having duly signed tags.
- Reference
- Manufacturers catalogue.
- Approved submittal.
- Shop drawings.
- Specification section 15700.
- Records
- `Work Inspection Request’ (WIR) duly signed by the Consultants.
8.2 Air Handling Unit installation checklist signed off by R&P.
