Project Info
This was an unusual project to supply two AHUs to provide ‘controlled’ conditions in isolation rooms at a hospital in Inverness, Scotland. What makes the project interesting is that the units would normally have been mounted within a building plantroom but there was nowhere in the building to install them. Weatherite therefore had to design a solution to meet stringent building regulations and ensure the systems could be maintained without the risk of personnel coming into direct contact with contaminated filters.
THE SOLUTION
Weatherite designed a bespoke weatherproof plantroom enclosure to house the two very large AHUs, so it could be lifted onto the roof for ease of maintenance. The plantroom was built to meet stringent BS6399 part 2&3 and BS5950 part 1 building regulations and had to undergo stringent factory tests prior to dispatch. These tests were carried out by structural engineering experts, Fairhurst, Inverness and were undertaken to simulate wind pressures and snow loads on the sides and roofs of the plantrooms. As the plantroom was categorised as Buildings, this was a mandatory requirement for Scottish Building Regulations.
Both units at Raigmore Hospital provide 100 per cent run and standby capability and can be swapped over in operation during maintenance and service work to ensure continuity of room conditions at all times. The design incorporated a number of elements essential in ensuring isolation of contaminated air, including negative air pressure, bespoke high efficiency filtration systems and high grade H10 HEPA filters.
The air handling system also included a ‘bag in, bag out’ arrangement for removing contaminated particulate filters and gas absorbers in hazardous environments. With this system, FM maintenance personnel are protected from coming into direct contact with the interior of the housing and hazardous containments during filter change-over. Other features include low-temperature hot water heating coils, integral DX cooling, with scroll compressor, and condenser heat rejection in exhaust pat, smoke rated exhaust fans and a separate extract system.
