A concept motel and American restaurant, Molly’s Diner, had recently been built in Oxford.

The standard, single extraction system fitted in rooms with a fan had developed teething problems. A consultant brought in to advise suggested a central core ventilation system, but this failed to work in practice. At this point Antony Grice was approached and asked to redevelop the entire system.

We quickly discovered that the root of the problem was the physical size of the ductwork that needed to fit into the relatively shallow riser cupboard. The specified volume control dampers – allowing the user to restrict or direct more flow into individual rooms – were a particular problem. We reverse engineered the original design to create a superior, bespoke solution that would also be quicker and easier to install.

The original consultant on the project insisted that the central core of the ventilation take the form of a spiral duct. We identified a versatile plastic moulding that would take up less space and allow sharper bends. We mocked up an exact replica of the riser cupboard in our workshop to calculate exactly what products were needed to build the system, including the ventilation, electrical services and hot and cold works. We then mixed and matched products to ensure all the parts fitted within the predefined moulds and were accessible within the restricted space.

To resolve the fire damper issue, we proposed use of a fire collar, which in the event of a fire will crush the plastic and stop any fire transmitting through the pipework from one side to another. This takes up less space, is more economical and 10% quicker to install.

The ongoing project has been successful so far, with all the original issues resolved. Some minor issues remain, such as the client and consultant’s request to modify the amount of spiral duct used. When complete and approved, it is expected that the re-engineered solution will be rolled out across all the client’s sites over the next few years.