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Investigative approach to improve hot water system hydraulics through temperature monitoring to reduce building environmental quality hazard associated to Legionella

Inès Boppe, Emilie Bedard, Catherine Taillandier, Daphné Lecellier, Marc-André Nantel-Gauvin, Manuela Villion, Céline Laferrière and Michèle Prévost

Article (2016)

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Cite this document: Boppe, I., Bedard, E., Taillandier, C., Lecellier, D., Nantel-Gauvin, M.-A., Villion, M., ... Prévost, M. (2016). Investigative approach to improve hot water system hydraulics through temperature monitoring to reduce building environmental quality hazard associated to Legionella. Building and Environment, 108, p. 230-239. doi:10.1016/j.buildenv.2016.08.038
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Abstract

Several countries have promulgated control measures and design guidelines to limit the proliferation of Legionella within hot water distribution systems (HWDS). However, there is little information on how to assess and improve existing HWDS unable to maintain water temperatures >= 55 degrees C throughout the system. A 50-year old hot water system of a 10 story hospital was investigated in terms of temperature distribution and Legionella pneumophila prevalence. Concentrations of L. pneumophila were correlated with the maximum temperature reached at the tap, with a significant decrease observed at T >= 55 degrees C. Continuous temperature and flow monitoring was performed on the overall HWDS, characterizing the principal and secondary horizontal return loops for all 9 wings, and detailed investigations of the secondary vertical return loops was completed in Wing 3. Results indicated the system inability to systematically maintain desired operating temperatures of 55 degrees C. The deficient hydraulic distribution was the root cause of the poor temperature maintenance throughout the secondary loops, but defective devices were also identified as playing an important role in sectorial temperature failure. A simple stepwise investigative approach was developed to identify hydraulic deficiencies. The implementation of flow restrictions on identified recirculation loops and increased pumping efficiency was conducted within a short period of 2 months, with no major system upgrade. These corrective measures resulted in a balanced system with increased flow velocities (>0.2 m/s). As a result, the proportion of taps achieving 55 degrees C within 2 min increased from 11% to 74% and L. pneumophila prevalence decreased from 93.1% to 46.1% after 4 weeks. (C) 2016 The Authors. Published by Elsevier Ltd.

Uncontrolled Keywords

legionella pneumophila; infectious disease; drinking water; hot water distribution system; hydraulic balancing; pneumophila; risk; disinfection; contamination; surveillance

Open Access document in PolyPublie
Subjects: 1000 Génie civil > 1000 Génie civil
1000 Génie civil > 1005 Génie hydraulique
1000 Génie civil > 1007 Ressources et approvisionnement en eau
Department: Département des génies civil, géologique et des mines
Research Center: Non applicable
Funders: NSERC Industrial Chair on Drinking Water
Date Deposited: 19 Jul 2021 15:55
Last Modified: 20 Jul 2021 01:20
PolyPublie URL: https://publications.polymtl.ca/4798/
Document issued by the official publisher
Journal Title: Building and Environment (vol. 108)
Publisher: Elsevier
Official URL: https://doi.org/10.1016/j.buildenv.2016.08.038

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