Where London's wet cooling lives
Most of London's cooling towers are hidden in plain sight. They sit on the roofs of City and West End office blocks, behind louvres on hospital plant floors, in basement plant rooms with ducted air paths, and on the podium decks of the bigger Canary Wharf buildings. Out in Park Royal, along the Lea Valley and beside the river in the east, you'll find the industrial side: food production, cold stores with evaporative condensers on the refrigeration plant, and warehouses that need chilled space all year.
Each setting changes how the job gets done. An office tower is usually close to openable windows, fresh-air intakes or a busy pavement, so drift control and a clean, well-treated pond matter to the people below. A hospital wants results passed straight to its Water Safety Group. A food site or cold store wants work fitted around deliveries and production. We plan the programme around the building, not the other way round.
Hard London water and what it does to a tower
London's mains water is mostly hard to very hard. Thames Water supplies most of the capital, with Affinity Water in parts of the north and west, Essex & Suffolk Water in parts of the east and SES Water in parts of the south. A lot of it starts life in the Thames, the Lee and the chalk, which is where the calcium comes from.
In a cooling tower, that hardness concentrates every time water evaporates. Push the cycles of concentration too far and calcium carbonate plates out on condenser tubes and fill, cutting heat transfer and giving biofilm somewhere to hide. So London towers usually run at fewer cycles than a soft-water site could, which means more bleed, more make-up and a scale inhibitor matched to the water. Some buildings soften the make-up to claw back water savings, but fully softened water can be harder on some metals, so corrosion then needs a closer eye. Our article on bleed and conductivity control explains the balance.
We test your make-up water rather than assume. You can check the published hardness for your postcode with Thames Water's water quality checker or your own supplier's equivalent.
Getting to roof plant in the capital
Chiswick is on the western edge of inner London, so most sites are a short trip for us. The journey is rarely the hard part. Reaching the tower is. Expect us to ask about:
- Roof access and permits. Many City towers are behind a locked hatch or plant-room door that needs a permit to work, a working-at-height plan and sometimes a check of the edge protection or fall-arrest system.
- Goods lifts and loading bays. Treatment chemicals come in drums. In a tall building that means booking the goods lift and a loading-bay slot, and sometimes agreeing a route through the building with security.
- Out-of-hours work. Cleans are noisy and wet, so some buildings prefer them at weekends or early in the morning before tenants arrive.
- Parking and charges. Central London means controlled parking zones, the Congestion Charge and the ULEZ. We sort the route and parking before the visit so nobody's circling the block with a van full of chemicals.
Send us your building's contractor rules and RAMS template up front and the first visit goes much more smoothly.
Notifying the council in London
The Notification of Cooling Towers and Evaporative Condensers Regulations 1992 say you must tell the local authority, in writing, about every wet cooling tower and evaporative condenser on your premises. In London that means the borough council your site is in, or the City of London Corporation if you're in the Square Mile. Your local council's environmental health team is the place to start. Our guide to notifying the local authority walks through what to send.