Fitzwilliam House is a prestigious large scale ‘occupied’ commercial building which sits in the shadow of the Gherkin in central London and is the UK headquarters for several specialist insurance companies. Following construction three decades ago it found itself in need of replacing its third generation of water chillers to serve the central air conditioning plant.

The building’s water cooled chiller plant is situated in the basement of the building, with a total installed capacity of 2 x 700kW. The chillers are significant in physical scale and access is incredibly limited as the basement plantroom is only served by a very small and low capacity goods lift. A narrow stairwell exists but is only suitable as an emergency exit. When the original chillers were installed they were positioned by crane into their location and the foundations and building constructed around them, this naturally renders the same replacement logic impossible today.

When the second generation of chillers were procured a compact/ demountable solution was required. With the heat exchangers being the largest items a decade ago, the solution opted for was to use ‘Plate-to-Plate’ compact heat exchangers on the chilled water and condenser water sides. Although plate to plate ‘HEX’s’ are efficient they can also be delicate, and due to other factors on site the heat exchanges regularly fouled with system debris, which led to localised freezing in the evaporators, and high condensing conditions in the condensers. Ultimately this led to the premature demise of the chillers.

CoolTherm were initially approached to replace one of the two machines to ensure the building had cooling to see it through the summer. As the machine needed to be fully demountable, CoolTherm saw this as the ideal opportunity to install the latest TT700 Danfoss Turbocor compressor which delivers 700kW of cooling and has an amazingly small footprint. Measuring only 800mm(l) x 500mm(w) x 500mm(d) and weighing only 144kg (a screw compressor by comparison would measure circa 1500mm x 900mm x 800mm and would weigh more than 1000kg). The TT700 compressor has been applied globally for some time however we believe it is the first application of its kind in the UK.

Flooded ‘Shell and Tube’ heat exchangers offer the site the robust build quality required along with incredibly high levels of thermal heat exchange efficiency, however they are physically very large and heavy. CoolTherm set about working with manufacturing partner Geoclima to construct compact flooded heat exchangers which could be mounted into the goods lift vertically and remain under the 1000kg limit of the goods lift.

The chillers were fully constructed, and performance tested in the Italian Geoclima factory before being shipped to CoolTherm’s Bristol facility for demounting and preparation for installation on site. The components were taken to site in the dead of night, as despite the building’s impressive scale it has zero parking and off-loading facilities. A specialist team of in-house CoolTherm engineers took the components through the building paying attention to the significant health and safety risk associated with moving such heavy components. Once the components were situated in the basement, the engineering team reassembled the machine back to ex-factory conditioning and commissioned it into operation. The chiller was operational just in time to serve the building throughout the UK’s hottest summer on record and performed exceptionally well, delivering chilled water non-stop while achieving excellent efficiency levels.

The chiller benefits from a hardwired remote monitoring system which allows CoolTherm service teams to monitor 24/7, with the aim to constantly optimise performance, and react instantly should a fault arise. The graphic below shows an example of what can be instantly downloaded via a secure web browser.