Installing an air handling unit is a significant project. Whether you’re replacing existing equipment or fitting out a new building, understanding the process helps ensure everything runs smoothly — and helps you ask the right questions of your contractors.
We’ve handled AHU installations across every type of environment — from busy retail environments in Epsom to 24-hour poultry processing facilities where shutting down wasn’t an option. Here’s what to expect from a typical installation, based on how we approach it.
Pre-Installation Planning
Good installation starts long before anyone picks up a spanner. The planning phase is where potential problems get identified and solved on paper rather than on site.
Key planning considerations:
- Access and delivery: How will the unit get into the building? AHUs are large and heavy. Crane lifts, plant room access, and delivery routes all need planning. On our major airport project, logistics planning was critical — we were replacing units within a live operational facility where access was heavily restricted.
- Structural requirements: Can the floor or roof support the unit’s weight? Are there any building modifications needed?
- Service connections: Where are the electrical supplies, water connections (if humidification is required), and drainage points?
- Ductwork coordination: How does the new unit connect to existing or planned ductwork? Are any modifications needed?
- Controls integration: How will the AHU communicate with the building management system?
Tip: The more thoroughly these questions are answered before installation begins, the fewer surprises you’ll encounter on site.
Site Preparation
Before the AHU arrives, the site needs to be ready to receive it.
Typical preparation work includes:
- Plant room cleared and cleaned
- Structural supports or plinths installed
- Electrical supplies run to the installation point
- Pipework roughed in (for water coils, humidifiers, condensate drains)
- Ductwork openings prepared
- Access scaffolding or platforms in place if needed
Skipping or rushing site preparation is a false economy. A properly prepared site means the installation team can work efficiently and safely.
Delivery and Positioning
AHU delivery requires careful coordination. Units are typically delivered in sections for assembly on site, though smaller packaged units may arrive complete.
For our retail complex project in Epsom, we supplied and installed a flat-pack AHU designed for high-capacity airflow in a busy store environment. The flat-pack approach meant we could get the unit into position through standard access routes and assemble on site — avoiding the need for major structural modifications.
The positioning needs to allow for future maintenance access. There’s no point installing a unit if engineers can’t reach filters, belts, and bearings for routine servicing. We always factor this into our installation planning.
Mechanical Installation
With the unit in position, the mechanical connections begin.
Typical mechanical work includes:
- Ductwork connections (supply and return air)
- Pipework connections (heating/cooling coils, humidifiers)
- Condensate drainage
- Vibration isolation (anti-vibration mounts, flexible connections)
- Weatherproofing (for external units)
Quality matters here. Poor ductwork connections leak air and waste energy. Inadequate vibration isolation transmits noise through the building. Shoddy weatherproofing leads to water ingress and premature failure.
Electrical Installation
The electrical work typically happens alongside or immediately after mechanical installation, covering main power supply connection, control panel wiring, sensor and actuator connections, BMS integration, and safety interlocks.
All electrical work should be carried out by qualified electricians and certified appropriately. Our Electroair division handles installation with certified engineers across all disciplines.
Commissioning
Commissioning is where the installation gets tested, adjusted, and proven to work correctly. This is not a box-ticking exercise – it’s a critical phase that determines whether the system actually performs as intended.
Typical commissioning activities:
- Pre-start checks: Verify all connections, clear any debris, check fan rotation direction
- Initial start-up: Run the unit and check for obvious problems (vibration, noise, leaks)
- Air balancing: Measure and adjust airflows to match design requirements
- Controls setup: Configure setpoints, control sequences, and alarms
- Performance verification: Confirm the unit delivers specified temperatures, humidity levels, and air volumes
- Documentation: Record all settings, measurements, and test results
Proper commissioning takes time. Rushing it leads to systems that never quite work as they should.
Handover
The final stage is handover – transferring the completed installation to the client or facilities team.
A proper handover includes:
- Operation and maintenance manuals
- As-built drawings
- Commissioning records and test certificates
- Training for facilities staff (how to operate, basic troubleshooting, filter changes)
- Warranty information
- Maintenance schedule recommendations
Don’t accept handover until you’re satisfied everything is complete and documented. It’s much harder to chase missing information six months later.
Common Installation Pitfalls
Problems we see regularly:
- Inadequate access: Units installed so tight that filter changes become a nightmare
- Poor coordination: Ductwork doesn’t align, services clash, installation drags on
- Skipped commissioning: System “works” but never delivers design performance
- Missing documentation: Nobody knows what the settings should be or how to maintain it
Most of these come down to poor planning or cutting corners to save time. The cheapest installation isn’t always the best value.
Working With i-Flow
At i-Flow Technologies, we don’t just manufacture air handling units — we support the full installation process through our Electroair division. From design coordination through to commissioning support, we work with contractors and end clients to ensure our equipment gets installed correctly and performs as intended.
View our completed projects to see examples of our installation work, or get in touch to discuss your requirements.
