Are closed systems a ‘closed book’?

Pre-commission cleaning of closed circuit pipework systems, and the subsequent monitoring of water quality, are essential in any building. Getting either wrong can mean disruption to occupants while systems are re-cleaned or, in the worst cases, complete closure of buildings while entire systems are ripped out and replaced due to early failure. However, according to Dr Pamela Simpson, a specialist in water microbiology who established water quality specialists, Whitewater Technologies, in 1998, and, Chris Parsloe, of Parsloe Consulting, although the risks associated with open systems (where the circulating water might come into contact with humans) are generally appreciated, there is less awareness of the problems that can affect closed systems. 

Aclosed re-circulating pipework system is one which, as the name implies, is closed, i.e. the water in them is not exposed to the atmosphere, and is not significantly depleted due to evaporation or draw-off. The water is permanently enclosed, and typically spends all of its time being heated, cooled, and re-circulated, in the process of delivering heating or cooling. All systems serving terminal devices – from radiators to fan coil units or chilled beams – are examples of closed systems. 

The potential problems start during construction. In large buildings, heating and cooling circuits can include pipes that are over a metre in diameter. In an ideal world, these pipes would be installed in a clean, debris-free condition, but in practice, nothing can be ruled out.