The Secret Tunnels of South Heighton

The Air Conditioning Plant Room.  Before & After 2000.

These pictures show the A/C plant room as found in 1993, and after clean-up by the Friends of HMS Forward.

A large fan in the far left-hand corner of the room drew-in untreated air from the adit outside the west airlock through the low-level air trunking on the left, and then through a bank of air filters to remove any air-borne dust or insects that might damage the treatment plant. It was expelled from the fan into ducting that no longer remains to route it to either bypass a gas decontamination plant under normal circumstances, or to pass through it in the event of a mustard gas attack. One remaining hand-operated 'valve' is visible in the distance. The gas decontamination equipment stood on the large concrete plinth to the right near the back of the room. Thereafter the air was forced through the now reinstated 'toppled' trunking towards the camera into an electric heater that sat upon three concrete stanchions. The heated air was then distributed to the main galleries by under floor trunking. The high-level trunking originally connected with the 'toppled' trunking to safeguard the fan motor by keeping air circulating to prevent the air pressure in the tunnel reaching a point where the motor was unable to draw-in further air. The excess air was returned to the adit outside the west airlock. Without a 'load' the motor's speed would increase and eventually destroy it. If you don't believe this, put your hand BRIEFLY over the input nozzle of a vacuum cleaner and hear the motor speed increase! 

The green frame on the right was the main electrical power panel where the public electricity supply or the output from the local standby generator could be selected as needs dictated. Normally the establishment ran on the 3-phase public electricity supply, but since an air-raid might damage the National Grid and interrupt the supply it was necessary, at every alert, to start up the diesel standby engine and run on locally generated power until the threat had passed. The work of sending/receiving or coding/decoding military messages was intolerant of the slightest interruption, and speed and accuracy was paramount.

Ken Wenham, a 14-year-old apprentice electricianís mate for a Brighton firm that specialised in contracts for the Admiralty, remembers them working on the main electrical switching and distribution frame terminating live 3-phase 440-volt cables. He described the precautions taken to cover the floor with thick rubber carpets and similarly insulate every exposed metal item within reach.


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All illustrations and text on this site are © 1941-2021 Geoffrey Ellis, or The Friends of HMS Forward, or Nick Catford.