Air Handling Unit Refurbishment & Upgrade

Project Overview

At Phoenix Air Handling Ltd, we were engaged to deliver a full refurbishment and upgrade of two existing Air Handling Units, alongside the supply and installation of new extract systems. The project required a careful balance between improving performance and working within the constraints of existing plant.

From the outset, the focus was on bringing the existing systems up to modern performance standards while maintaining reliability and ease of maintenance.

Understanding the Existing System

Both units had reached a point where key components were no longer performing efficiently. The existing fan assemblies, filtration stages and coil arrangements were limiting airflow performance and energy efficiency.

Our approach was not simply to replace like for like, but to re-engineer the internal layout to improve overall system operation.

This included full strip-out of:

• Existing fan and motor assemblies

• Frost coils and associated pipework

• Filter sections and access arrangements

This created a clean starting point to rebuild the units with improved components and better airflow paths.

Refurbishment & Performance Improvements

The upgraded systems were designed to deliver improved efficiency and more stable control across both heating and cooling conditions.

New rigid bag filtration (F7 grade) was introduced to improve air quality while maintaining acceptable pressure drops.

A key part of the upgrade was the integration of run-around coil systems. These were designed to recover energy and stabilise air temperatures across seasonal conditions, delivering strong performance in both winter and summer operation. 

The systems were designed to handle:

• Low external temperatures while maintaining supply air conditions

• High summer loads with controlled humidity levels

• Efficient fluid circulation with optimised flow rates and pressure drops

This resulted in a more balanced and energy-conscious system overall.

Fan & Airflow Design

The fan upgrades were a critical element of the project.

New EC motor-driven fans were installed, selected to provide:

• Consistent airflow delivery

• Improved energy efficiency

• Reduced maintenance requirements

With airflow volumes ranging up to over 4 m³/s and external static pressures around 400 Pa, the systems were engineered to meet the demands of the building while maintaining reliable operation. 

Attention was also given to acoustic performance, ensuring the upgraded units remained suitable for their operating environment.

New Extract Air Handling Units

Alongside the refurbishment works, new extract Air Handling Units were supplied and installed.

These were constructed using:

• Aluminium framework with double skin panels

• Mineral wool insulation

• Weather-resistant external finishes

The units were designed for external installation and built to withstand operating conditions while maintaining thermal and acoustic performance.

Each unit included:

• High-efficiency EC fans

• Integrated filtration• Extract coil systems

• Weather louvre discharge

This ensured a fully matched system between supply and extract, improving overall system balance.

Flat Pack Delivery & Site Assembly

Due to site constraints, the units were supplied in flat pack form and assembled in position.

This allowed:

• Easier access into restricted plant areas

• Reduced lifting requirements

• Greater flexibility during installation

Our team managed offloading, positioning and full reassembly on site, ensuring the final installation met both design and practical requirements.

Delivering a Practical Solution

This project is a good example of how refurbishment, when done properly, can deliver results comparable to new installations.

Rather than replacing entire systems, we were able to:

• Extend the life of existing plant

• Improve efficiency and performance

• Introduce modern components and control capability

All while working within the physical limitations of the existing setup.

The Result

The upgraded systems now provide:

• Improved airflow and system stability

• Better energy performance through heat recovery

• Enhanced air quality through upgraded filtration

• More reliable and maintainable equipment

This project demonstrates Phoenix Air Handling’s ability to deliver bespoke, application-led air handling solutions, combining technical expertise with practical site awareness and strong project coordination.

Case Study – Multi-Zone Air Handling Upgrade for an Educational Facility

Project Overview

Phoenix Air Handling was appointed to design, manufacture, and support the replacement of multiple air handling units serving key areas within an educational facility. The project required a tailored solution to serve distinct environments, including a commercial kitchen, a large assembly space, and a specialist hydrotherapy area, each with very different ventilation, temperature, and air quality requirements.

Our role covered detailed design development, equipment specification, manufacture, and coordination with site teams to ensure a smooth installation process.

The Challenge

The facility required three bespoke air handling systems, each designed to meet specific operational needs:

• High-efficiency ventilation for a food preparation area

• Balanced supply and extract with heat recovery for a large occupied space

• Controlled temperature, humidity, and corrosion resistance for a hydrotherapy environment

In addition, the units needed to achieve strong energy performance, comply with current regulations, and integrate seamlessly with existing building services and control systems.

The Solution

Phoenix Air Handling designed and supplied three bespoke air handling units, each engineered specifically for its intended application.

Key features across the systems included:

• High-performance EC fans delivering low specific fan power

• LPHW heating coils designed to meet space-specific heating demands

• Plate heat exchangers providing efficient heat recovery where required

• Multi-stage filtration with pressure monitoring for maintenance efficiency

• Robust aluminium framework with insulated panel construction for durability and thermal performance

• Fully integrated controls, including time scheduling, fire alarm interlocks, dirty filter indication, and remote enable facilities

For specialist areas, materials and finishes were selected to suit internal or external installation environments, including corrosion-resistant construction where required.

Installation & Coordination

The project also involved careful planning around removal of existing units, modular delivery, and coordination with other contractors on site. Phoenix Air Handling supported the process by:

• Supplying units in modular form where access was restricted

• Coordinating delivery and positioning logistics

• Providing installation guidance and supervision during critical lifts

• Ensuring controls and interfaces were configured for smooth commissioning

This collaborative approach helped minimise disruption and ensured the systems were installed efficiently and safely.

The Outcome

The completed systems provide:

• Reliable and efficient ventilation across all served spaces

• Improved energy performance through heat recovery and efficient fan selection

• Flexible control and monitoring for ongoing operation

• Systems designed around the real demands of the building and its users

This project demonstrates Phoenix Air Handling’s ability to deliver bespoke, application-led air handling solutions, combining technical expertise with practical site awareness and strong project coordination.

Case Study – Commercial Office Development, Central London

Project Overview

Phoenix Air Handling Ltd was appointed to design and supply a complete air handling and ventilation solution for a high-profile commercial office development located in Central London.

The project required multiple Air Handling Units and extract systems to serve a large, modern office space, with a strong emphasis on energy efficiency, acoustic performance, and reliability, while meeting current building regulations and sustainability expectations.

The Challenge

The development demanded a flexible and efficient ventilation strategy capable of supporting high occupancy levels and varying operational demands throughout the building.

Key challenges included:

• Delivering high airflow volumes within strict external static pressure constraints

• Achieving excellent energy efficiency to comply with ErP requirements

• Managing acoustic performance suitable for a premium office environment

• Coordinating multiple external and internal units within limited plant space

• Providing an integrated controls solution to allow simple operation and future adaptability

The Solution

Phoenix Air Handling Ltd designed and supplied a bespoke air handling package consisting of:

• Two external Air Handling Units serving primary supply and extract ventilation

• One internal twin extract fan unit

• Additional in-line extract fans to support localised ventilation requirements

Each Air Handling Unit was manufactured with an extruded aluminium framework, insulated panels, and a durable external finish suitable for rooftop installation.

High-efficiency thermal wheel heat recovery was incorporated within the main Air Handling Units, achieving ErP efficiency classifications of H1 and significantly reducing energy demand during both heating and cooling seasons.

Integrated DX heat pump systems provided both heating and cooling duties, ensuring year-round thermal comfort while maintaining efficient system operation.

Technical Highlights

• Supply air volumes up to 4.04 m³/s

• Extract air volumes up to 3.59 m³/s

• Specific Fan Power as low as 2.05 W/l/s

• Heat recovery efficiencies approaching 80%

• EC fan technology for improved efficiency and controllability

• Duplex fan arrangements for resilience and operational continuity

• Fully fitted controls with MODBUS RTU capability for BMS integration

All units were supplied with fitted controllers, enabling precise fan control, heat recovery management, heat pump operation, time scheduling, and system interlocking.

Installation & Commissioning Support

Phoenix Air Handling Ltd provided post-installation checks and controls commissioning support to ensure the systems were correctly installed, configured, and operating as intended.

This included:

• Verification of unit assembly and sealing

• Inspection of access doors, panels, and ancillaries

• Validation of control inputs and outputs

• Set-point configuration and system demonstrations

This approach ensured a smooth handover and reduced the risk of commissioning delays.

The Result

The completed air handling solution delivers a robust, energy-efficient ventilation system aligned with the operational needs of a modern commercial office environment.

The system provides:

• Consistent indoor air quality

• Reduced energy consumption through high-efficiency heat recovery

• Quiet operation suitable for office use

• Flexible control and future BMS integration

The project demonstrates Phoenix Air Handling Ltd’s ability to deliver tailored Air Handling Systems solutions for complex commercial developments, combining technical expertise with a practical, project-focused approach.