25939985_mUK: Precise environmental control is a necessity to ensure passengers on the London Eye, at one time the world’s largest cantilevered observation wheel, have an unobscured view of the capital city.

To ensure the right conditions are maintained, a Colman Moducel system installed in 2002 was replaced by a Dunham-Bush water-based chiller system. 

The new air conditioning system was part of a £12.5m upgrade plan initiated by owners Merlin Entertainments in 2009 in an effort to make the London Eye run more efficiently and cut down on its carbon emissions.

Built to celebrate the millennium, the 120m diameter, 135m tall London Eye comprises 32 ovoidal capsules, offering visitors a panoramic view of London and up to 40km in all directions.

Working alongside the Sweett Group, Dunham-Bush was commissioned to upgrade the capsules with a temperature control solution to ensure visitors enjoy views across London, no matter the weather.

“Each 8m capsule fitted to the London Eye needs specific environment-control requirements depending on time of day, number of passengers and prevailing weather conditions as the London Eye rotates,” explained Dunham-Bush md Mike Holding. “The ride is around 30 minutes which means comfortable conditions within the capsule need to be achieved as quickly as possible and then maintained for the remainder of the ride.

“Extremes of temperature and humidity must be managed – from the environments that crowds of visitors on hot sunny days create, to visitors with wet coats on rainy days. Not only do passengers need to be comfortable on their journey, but the glass in each capsule must remain free from condensation to ensure a clear view of the capital.”

Dunham-Bush designed and manufactured a climate control system to be installed into each of the capsules. This new system was developed to improve comfort and prevent condensation through temperature and humidity control, and fresh air introduction.

A two-circuit 15kW air cooled chiller module is mounted under the floor of the capsule. Each is equipped with four-scroll compressors, two plate heat exchangers and two air-cooled condensers fitted with EC fans. Two Dunham-Bush VBH 1200 Q air handling units, each equipped with cooling coils, filters and electric heater elements, are also used to pre-condition 280 l/s of fresh air before introduction into the capsule. The modular arrangement allows a complete chiller to be lifted out of a capsule and replaced with minimum disruption to the operation of the attraction, should the need arise.

Two Dunham-Bush Panther 7 fan coils installed in the roof of each capsule maintain comfort conditions in the space and ensure the glass is clear.

“Our engineers had to adapt the initial design for installation at an angle to fit the roof void with multiple air discharge paths to distribute the air along the length of the capsule,” Mike Holding revealed.

The AHUs and FCUs are controlled from a single controller which also monitors the chiller, ensuring a fully integrated system that responds to the prevailing conditions at all times.

“Once passengers enter the capsule and the doors close, the first obligation is to achieve the design temperature within the capsule through the AHUs. Once the temperature has been achieved, the Panther FCUs ensure comfortable conditions are maintained for the passengers for the duration of their journey.”

All the capsules have now been upgraded and are said to have been proven over at least one full season with excellent results.