Air Handling Unit Refurbishment 

Kettering General Hospital


The existing ventilation system had a requirement to upgrade the filtration within the air handling unit to include HEPA filters within the supply ductwork.  As part of the works to the air handling unit, we were asked to modify the AHU to comply with current HTM-03 regulations.





A bespoke HEPA filter bank was installed into the supply ductwork with new transitions installed to ensure smooth airflow across the filters. The belt driven fan with run and standby motors was upgraded to new duplex direct drive EC plug fans to overcome the additional pressure drop from the HEPA filters. The BMS was upgraded to suit the modifications of the EC fans running simultaneously. 


Energy Saving Report

We conduct energy saving reports for all our delivered projects. No matter how small the saving may seem, a saving is a saving. 

Typically, we deliver a 40% saving on every delivered project. 





Fan Upgrade & AHU Remodelling

Prior to installation Halo HVAC validated all technical aspects of the system, designed structural modifications of the AHU, pre-wired all fans, along with Internal-rotor motor PM/EC technology that boasts an efficiency of IE6,  exceeding motor energy efficiency classes set by both the International Electrotechnical Commission and European Efficiency. 


The new maintenance-free fans were installed into the Air Handling Unit, for both supply and extract air streams. Along with bespoke manufactured reinforced bulk heads and fan openings for a seamless installation.


This combines three solutions in a way that previously seemed almost impossible: Reliability, outstanding system efficiency with high-power density for environmental control and 15–20-year extended life cycle for each AHU. 



HALO HVAC AHU refurb - air handling unit refurbishment

High Efficiency Filtration System 


Although we have been known to utilise IAQ technologies such as UVGI, ionisation treatment, to improve indoor air quality (IAQ). Considering the nature of a hospitals function, the likelihood of potential side-effects and down time is much lower with a suitably designed and maintained high-efficiency filtration system.


The system we developed and installed has ease and simplicity of maintenance at the forefront. We installed a new high-quality air filtration system designed to effectively capture and remove airborne contaminants. The new filtration system is compliant to ISO 16890-1:2016, EN 779:2012, DIN 53438-3 (F1) and OEKO-TEX® 100. 


With Halo HVAC IOT it is possible to continuously remote monitor IAQ and accurately adjust based on live data to guarantee a consistent maintenance schedule.




AHU (asset) life extension

Issues arising from AHUs ageing present key challenges for building services. Technological advances and ever-changing compliance requirements, means that there are many air handling units operating beyond their originally conceived application. As HVAC equipment ages, increased challenges to maintaining integrity require to be managed – coinciding with potential declining financial value. This may be a result of cumulative degradation over time such as neglect, corrosion, rust, microbial growth, and environmental conditions such as serving a greater occupancy than when the AHU was first designed, and therefore the AHU doesn't achieve the airflow and thermal conditions required. Where like for like replacements is no longer suitable due to either obsolescence or changes in engineering standards Halo HVAC will have a solution. 




Over time, this air handling unit suffered with degradation, largely due to a lack of maintenance and required fan, coil and filter remediation, a full service, a deep clean, including VOC free rust treatment, new doors, air leakage seals throughout, and damper repairs to meet compliance. 


Additionally, upgrading an AHU prevents unforeseen downtime, improved maintenance, compliance, efficiency, and added value to the asset in its entirety. Halo HVAC conducts asset audits, covering planned preventative maintenance, monitoring, risk management, and financial evaluation including return on investments.

Project Delivery ☆☆☆☆☆

Hospitals operate 24/7 therefore we had to deliver this project with minimal disruption. We completed all works in 2 days and staged the works to allow for ventilation to continue during peak hours.  The system deep clean, new coil installations, pipe work modifications and rust treatments were conducted and commissioned on the first morning.  The new filtration systems, fan upgrades, damper remediation, new anti-leakage seals and commissioning, and BMS integrations were carried out the following evening. 





HALO HVAC AHU refurb - air handling unit refurbishment

To enable an efficient “hassle-free” project delivery, and apart from the coils that were custom built within the unit, most components were pre-designed and fabricated off site. Ensuring safety, compliance, and risk mitigation to support an impeccable project delivery. This process enabled us to maximise on site time and guarantee the health and safety of everyone throughout the entirety of this project. 





Upgrade of the BMS, the AHU communications, all wiring, & panel modifications

The existing legacy controller information, AHU panel and SET files were uploaded with a backup taken, fully checked over for any errors prior to any modifications. Then the software was updated and modified with new security features and speed control operation for the new high efficiency EC fan arrangement and associated sensors.


Enabling the future; HALO disconnected the existing cabling and removed legacy inverters. We then conducted the Installation of all new wiring for each fan output with new bespoke AHU breaker box, terminations, isolators and all new BMS interfaces and controls. 


The new BMS system was then fully validated and commissioned to enable the new fans to perform as per the air flow validations carried out by HALO HVAC using our own BSI and UKAS accredited BSRIA calibrated airflow and pressure reading equipment.



HALO HVAC AHU refurb - air handling unit refurbishment



Conformity & Compliance

HALO HVAC Ltd has passed industry leading conformity and compliance testing, verification, and inspection. Our accreditations highlight our technical competences, reliability, and integrity to provide confidence and trust to deliver our services.


We hold insurances for Contractors All Risk, Professional Indemnity, Employer Liability, Public and Product Liability, and Contract Works. We are members of Constructionline, Building Engineering Services Association, and The Contractors Health and Safety Schemes in Procurement including PAS91 and SSIP.


Call to request copies on 0207 117 2087 or email


Clean Room & Labs, Chandlers Ford 

13 Air Handling Units serving a critical manufacturing process and science laboratories, all requiring refurbishments, controls and BMS modifications, delivered in 5 days, whilst achieving 26t a year CO2e reduction.


5 Star Hotel, Knightsbridge, London

The belt-driven fans in the hotel's air handling units failed, causing no ventilation in critical areas; urgent reinstatement was essential for to ensure the Hotel was fully operational & compliant.


Kettering General Hospital

Bringing the Air Handling Unit in line with compliances such as HTM 03-01 whilst reclaiming lost heat through new ventilation strategies, enabling energy savings.


Food Manufacturer, Rugby

Ventilation is vital for food production, ensuring air quality and contamination prevention. Upgraded filtration and AHU refurbishment guaranteed compliance, reliability and effectiveness.


Offices. Gracechurch Street, London 

With the building owners advertising for new leases a key objective was to ensure the indoor environment is comfortable and healthy. Over time, the existing AHUs became less efficient, leading to higher energy bills and reduced indoor air quality.


5 Star Hotel. Mayfair, London

This luxury hotel operates 24/7 therefore we had to deliver this project with zero disruption. We completed all works in 2 evenings whilst staging the works to allow for ventilation to continue during daytime hours. 


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