Didcot Ambulance Resource Centre, Oxfordshire – replacement of roof-mounted supply and extract ventilation plant, roof-level ductwork, associated LPHW and electrical services, controls integration and commissioning, coordinated around a full flat-roof replacement at a live operational site.
The brief
ComGas was appointed to support a major flat-roof replacement at Didcot Ambulance Resource Centre. The existing roof carried extensive ventilation ductwork, associated services and the main air-handling equipment, all of which had to be surveyed, isolated and either removed or repositioned before the roofing works could proceed.
The original intention was to retain and reinstate as much of the existing installation as practical once the new roof system was complete. Before work began, ComGas carried out a detailed condition survey of the ventilation plant, ductwork, pipework, controls and associated electrical services.
The survey changed the solution
The survey found the existing ventilation plant to be in significantly poorer condition than expected. Water ingress was evident at numerous unit seals, sections of the LPHW pipework were corroded and leaking, a heat-exchanger return was blocked, valves had seized, internal dampers were not operating correctly and the existing electrical isolators showed signs of deterioration.
The roof-level ductwork was assessed separately. Some sections remained sound and suitable for reuse, but the external insulation and weather protection had deteriorated and could not simply be reinstated.
Rather than remove and reinstall ageing plant carrying a high risk of further failure, ComGas recommended replacing the main ventilation equipment and incorporating the necessary ductwork, mechanical, electrical and controls works into the roofing programme.
A coordinated replacement
The revised installation centred on new Nuaire DAVE supply and extract ventilation units – a DS7A-LES supply unit with LPHW heating coil and a DE7-ES extract unit – both using Nuaire Ecosmart controls.
The existing roof-level installation was stripped back to give the roofing team the access needed to complete the new roof. As that work progressed, ComGas installed the replacement ventilation plant on purpose-designed non-penetrative support systems and rebuilt the roof-level distribution around the new arrangement.
Existing ductwork was retained where its condition allowed, with new sections and transitions installed where required. The completed system was finished with new external insulation and weather protection suitable for an exposed rooftop environment. Associated LPHW pipework, electrical connections and control interfaces were renewed or adapted as part of the same package.
Work of this kind sits within the HVAC and ventilation services ComGas provides, alongside the commercial electrical elements delivered by the same team.
Working around a busy ambulance station
Careful coordination was particularly important because the works were being carried out at a busy operational ambulance resource centre.
ComGas worked closely with the project consultant and roofing team to sequence the removal, replacement and reinstatement works efficiently. This allowed the roofing programme to progress while keeping disruption to the site’s day-to-day operation to a minimum.
The project shows the value of treating mechanical, electrical and controls requirements as one coordinated building-services package rather than a series of disconnected tasks – the approach ComGas takes across public sector and local authority buildings.
Controls and commissioning
The existing control strategy was retained where appropriate and integrated with the new Nuaire plant. Ecosmart NET communications were connected between the plantroom and the new supply and extract equipment, with fan operation, speed settings and temperature control checked during commissioning.
On completion, fan operation and rotation were verified, the wall-mounted controller and valve actuator response were tested, airflow was confirmed at internal outlets and the system was left running with no faults reported.
Integrating new plant with an existing control strategy is a routine part of the building management systems and controls work ComGas carries out.
Technical summary
- Nuaire DAVE DS7A-LES supply ventilation unit with LPHW coil
- Nuaire DAVE DE7-ES extract ventilation unit
- Nuaire Ecosmart controls and NET communications
- Purpose-designed non-penetrative rooftop support frames
- New and adapted roof-level ductwork
- New external weatherproof duct and pipe insulation
- Associated LPHW, electrical and controls works
- Testing and commissioning
The result
The completed works gave Didcot Ambulance Resource Centre a renewed roof-level ventilation installation, coordinated around the replacement roof.
Ageing ventilation plant was replaced with modern Nuaire supply and extract equipment, exposed ductwork and weather protection were renewed where required, associated services were upgraded, and the system was returned to operation following full commissioning.
For ComGas the project brought together surveying, HVAC, ductwork, LPHW services, electrical work, controls and commissioning, delivered collaboratively with the project team in a live public-sector environment. ComGas also provides planned service and maintenance for ventilation and plant installations of this kind.
