Dry/wet cooling systems

Some systems are designed to operate both in dry air cooled mode and wet evaporative cooling mode. There are different types of dry/wet cooling systems, sometimes referred to as ‘hybrid' or ‘adiabatic’ coolers, and these can have a wide range of risk profiles.

There is guidance on these systems in described in Part 1 of Legionnaires’ disease: Technical Guidance.

The Water Management Society, has published a document, endorsed by HSE, called The Control of Legionella in Dry/Wet Cooling Systems. It provides more detailed information to help evaluate between different designs and risk profiles of dry/wet cooling equipment.

This guidance is for dutyholders, including employers, those in control of premises and those with health and safety responsibilities for others. It will help them comply with their legal duties and gives practical advice on how to assess and control the risks due to legionella bacteria in dry/wet cooling systems.

This guidance is freely available to download from the Water Management Society.