OPINION | WATER QUALITY Corroding influence Good water quality is essential for good heat-network performance, says Telford Homes Chris Savoy MADE IN GERMANY High Grade Expansion Joints from ELAFLEX For piping systems of building services, you need compensators to absorb thermal expansion, reduce vibration and noise. ERV rubber expansion joints from ELAFLEX, setting standards for decades and offering the ideal solution. Type ROTEX is an EPDM Rubber Bellows ( PEEK reinforced ) for both LPHW and MPHW to 130 C constant temperature. DIN 4809 approved, no obligation to dismantle this type within 10 years. Many other ERV types available, e.g.: ERV-R: WRAS Approval Type TA: fitted with a white PTFE lining for extensive chemical resistance, FDA approved ERV-GR: for Acids, Alkali and aggressive chemicals ERV-W: white Nitrile ( NBR ) to foodstuff standards ERV-GS: ISO 15540 ( fire resistant ) Email your enquiry to: sales@elaflex.co.uk Check out our configurator: ervconfigurator.elaflex.co.uk ELAFLEX Ltd. Riverside House, Plumpton Road Hoddesdon, Herts EN11 OPA Ph. 01992 45 29 50 E-mail: sales@elafl ex.co.uk www.elafl ex.co.uk Ad_2020_ERV_90x270_Ltd_EN.indd 1 58 October 2020 www.cibsejournal.com CIBSE Oct20 p58 Chris Savoy Telford Homes.indd 58 T elford Homes is a large build-to-rent developer working predominantly in the London area. Over the past few years, we have been improving the quality of the design and delivery of our district heating installations, with the assistance of FairHeat, a specialist in heat networks with which we work on all our projects. Obviously, it is important that the design is correct, with controls in place that allow plant to operate as intended. One thing of which we have become increasingly aware, however, is the importance of correct water quality. For what is required, we turn to BSRIA BG29/2020 PreCommission Cleaning of Pipework Systems (the 6th, revised edition has just been published). Everyone, Im sure, is aware of the importance of leaving a system with the correct chemical inhibitor present, but what you may be less aware of is that this needs to happen from the minute the pipework is filled with water, because corrosion starts straight away and is irreversible Water in all parts of the system also needs to be kept moving, so consideration must be given to how the system will be progressively filled, using system pumps where possible to keep the water circulating. This is particularly important when projects take several years to complete and the works phased, and temporary pumps may be required. With the increased use of plastic pipework, oxygen introduced in the fill water has nothing to attack, which leaves any metal in the system such as boiler plant or radiators as a target. To ensure water quality is optimal, regular samples need to be taken from all parts of the system and analysed, and additional chemical adjustments made if it is found to be deficient. As advocated in BG29, plotting the results on a graph over time shows trends in the chemical properties and provides evidence about the state of the system. Trends are useful because chemical parameters that are above their limits, but which have stabilised, are less of a concern than those within the limits but increasing, as this indicates corrosion is taking place. BG29 now includes more focus on thin-walled carbon steel pipe, which because of its thin wall elevates the importance of correct water treatment where it is used. Although this all sounds expensive, bear in mind that once a building is occupied the potential cost of remedials to systems because of poor water quality would far outweigh the investment. CHRIS SAVOY is head of services at Telford Homes 20.07.2020 10:43:40 25/09/2020 18:41