MBS/Specific/TBT-MBS-014

AHU (Air Handling Unit) Installation

Mechanical Building Services › Specific › AHU (Air Handling Unit) Installation

Presenter		Project
Location		Date

Air handling units (AHUs) are large assemblies that filter, heat, cool, and distribute air through buildings.
AHU sections can weigh several tonnes each and require planned crane lifts or specialist rigging into plant rooms.
Installation involves connecting ductwork, pipework, electrical supplies, and control systems to each AHU section.
Restricted plant room access makes delivery, positioning, and connection of AHU sections particularly challenging.
Sheet metal ductwork connections create sharp edge laceration hazards during handling and fixing.
Lifting AHU sections through roof openings or into plant rooms requires specific lift plans and exclusion zones.
LOLER 1998 requires a lift plan for every AHU section lifted by crane or specialist handling equipment.
Electrical connections to AHU motors, heaters, and controls must be carried out by competent electricians.
Commissioning involves running fans, testing airflows, and balancing the system — noise levels can be very high.
Insulation of AHU casings and ductwork connections generates dust and fibre requiring RPE and extraction.

Lifting hazards	AHU sections are heavy and awkward — dropping them during installation causes fatal crush injuries in confined plant rooms.
Sharp edge injuries	Sheet metal ductwork and AHU casing edges cause deep lacerations to unprotected hands and arms.
Electrical safety	AHU motors and heater banks operate at dangerous voltages — isolation and competent connection are essential.

Don't

Prepare a specific lift plan for every AHU section placed by crane or specialist rigging
Plan the delivery route and confirm door widths and floor loading before moving AHU sections
Wear cut-resistant gloves when handling sheet metal ductwork and AHU casing sections
Ensure only competent electricians make electrical connections to AHU motors and heaters
Establish exclusion zones below all crane lifts during AHU placement through roof openings
Isolate electrical supplies before working on AHU wiring, controls, or motor connections
Wear hearing protection during AHU commissioning when fan noise exceeds 85 dB(A)
Use RPE when installing insulation on AHU casings and ductwork connections
Coordinate AHU installation with other trades in the plant room to prevent access conflicts
Commission and balance the AHU system fully before handing over to the building operator

DON'T lift AHU sections without a specific lift plan approved by the appointed person
DON'T handle sheet metal ductwork without cut-resistant gloves — edges cause deep lacerations
DON'T force oversized AHU sections through restricted openings — plan the route in advance
DON'T make electrical connections to AHUs unless you are a qualified and competent electrician
DON'T stand beneath AHU sections being lifted through roof openings or into plant rooms
DON'T run AHU fans during commissioning without hearing protection for all nearby workers
DON'T leave AHU access panels open where other workers could contact rotating fan components
DON'T install insulation on AHU casings without RPE for dust and fibre protection
DON'T energise AHU heater banks without confirming airflow is established through the unit
DON'T block plant room access with packaging and offcuts during AHU installation work

See also: HVAC System Installation Safety | Ductwork Installation Safety

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