The site comprised two ageing Visco cooling towers serving a high-value London commercial property. The towers were originally constructed with:
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316 stainless steel casing
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Mild steel centrifugal fans
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Gravity-fed distribution
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Ageing packing and drift eliminators
While structurally sound, performance and compliance standards had evolved. The towers required upgrading to meet revised duty requirements without full replacement.
In Central London, traditional replacement would have introduced significant logistical challenges:
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Road closures and cranage
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Structural loading reviews
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Pipework re-routing
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Control system modifications
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Programme disruption
The client required a refurbishment partner capable of upgrading non-Vistech towers, working within tight urban constraints, and delivering a long-term engineered solution.
Client Requirements
The project required:
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- Increased thermal performance to meet revised duty
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Upgrade from gravity distribution to spray system
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Replacement of pack and drift eliminators to anti-legionella standard
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Improved access and maintainability
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Replacement of fans with high-efficiency stainless assemblies
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Installation of safe internal working platforms
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Minimal external disruption
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Sequential works to maintain site resilience (one tower at a time)
Additionally, the solution needed to comply with ACOP L8 and HSG274 guidance while enhancing long-term reliability.
Solution
Vistech delivered a complete engineered refurbishment of both towers, demonstrating our capability to modernise and upgrade towers manufactured by other OEMs.
Key Engineering Interventions:
1. Stainless Steel Fan Upgrade
The existing mild steel centrifugal fan units were removed and replaced with:
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316 stainless steel split casings
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316 stainless steel DIDW impellers
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Precision-ground stainless shafts
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Auto-lubrication systems
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Siemens IE4 high-efficiency motors
Split casings allowed roof manoeuvring without cranage — critical in a Central London environment.
2. Gravity to Spray Distribution Conversion
The ageing gravity system was replaced with a high-efficiency spray distribution system constructed from:
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GRP reinforced uPVC
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Stainless steel fittings
This improved water distribution uniformity, increased thermal performance and supported the increased pack depth
3. High-Efficiency Anti-Legionella Packing
New modular 12mm flute anti-legionella PP packing (800mm depth) was installed.
Benefits included:
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Lower pressure drop
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Easy removal for inspection (aligned with HSG274 Pt1 guidance)
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Self-supporting welded construction
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Long-term UV and chemical resistance
4. Stainless Steel Framed Drift Eliminators
New stainless-framed cellular eliminators were installed with:
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<0.0005% drift loss
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T-bar air seals to prevent bypass
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Closed-cell design maximising droplet capture
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ACOP L8 compliance
5. Cleansafe Flooring & Access Improvements
To improve safety and maintainability:
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GRP Cleansafe flooring installed beneath pack
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New stainless steel access doors added
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Sump doors replaced and resealed
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Horizontal casing joints split and re-masticed
This created a safe internal maintenance platform and extended casing service life.
Vistech Delivery Capabilities
Central London Delivery
The refurbishment was delivered within a constrained Central London environment, avoiding:
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Cranage
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Road closures
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Structural modifications
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Pipework reconfiguration
Split fan casings and modular internals enabled manual roof manoeuvring, reducing programme risk and minimising disruption.
Asset Life Extension
By retaining the existing 316 stainless steel casing, the project avoided unnecessary embodied carbon and extended asset life—while delivering an upgraded system that, in key areas, exceeds typical new galvanised replacement standards.
Engineering-Led Approach
Rather than replacing plant, Vistech re-engineered critical performance drivers, including:
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Air movement efficiency
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Water distribution uniformity
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Heat transfer capacity
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Drift control and compliance
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Access, safety and maintainability
Multi-OEM Refurbishment Capability
Vistech successfully upgraded Visco-manufactured towers, demonstrating our ability to deliver engineered retrofit solutions across multiple OEM platforms.
Our refurbishment approach is not constrained by original manufacturer limitations, enabling performance-driven upgrades tailored to site requirements.
Feedback from the client
Kristian Gjetani
Leonari
Get in touch
The Vistech team are always happy to help with any stage of your cooling system project.
