Most of the guidance available for closed water systems revolves around installation and commissioning. BG 50/2021 – Water Treatment for Closed Heating and Cooling Systems, and BS 85521:2012 – Sampling and monitoring of water from building services closed systems, do caveat that structured sampling and valve exercising is essential for the ongoing management of the system, not just during commissioning.
A good sampling regime coupled with a good valve exercising regime, is key to keeping closed systems healthy throughout their lifespan. Without regular water sampling and monitoring as part of an on-going maintenance regime, it is very difficult to see if issues like corrosion, solid deposits, or heavy bacterial growth are occurring, until it is too late. If left unchecked, poor water quality can lead to reduced performance and expensive repairs.
A robust sampling regime should be risk based and tailored to the size and complexity of each system. Guidance suggests that multiple sampling locations should be considered dependant on the system size and number of terminal units (e.g. fan coil units and radiators). New systems typically will need more frequent monitoring as system chemistry settles, particularly in buildings where tenant fitouts are connecting to the landlord system, which can cause turbulent conditions. BG 50 states that all areas of each system should have flow for at least 1 hour in every 24-hour period, this makes sure that there is regular contact with chemical inhibitors and biocides and helps prevent stagnation, and bacterial growth.
Equally, it is important to maintain accurate records and carry out trend analysis of the chemical and bacterial results received. Spotting increasing trends can help identify problems before they occur and allow remedial action that maintains protection of the systems. Ultimately, a well-managed sampling regime supports the efficiency of a closed system, extends the lifespan of plant equipment, and helps avoid costly remedials.