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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, Émilie Bédard, Catherine Taillandier, Daphné Lecellier, Marc-André Nantel-Gauvin, Manuela Villion, Céline Laferrière and Michèle Prévost

Article (2016)

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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

Subjects: 1000 Civil engineering > 1000 Civil engineering
1000 Civil engineering > 1005 Hydraulic engineering
1000 Civil engineering > 1007 Water resources and supply
Department: Department of Civil, Geological and Mining Engineering
Funders: NSERC Industrial Chair on Drinking Water
PolyPublie URL: https://publications.polymtl.ca/4798/
Journal Title: Building and Environment (vol. 108)
Publisher: Elsevier
DOI: 10.1016/j.buildenv.2016.08.038
Official URL: https://doi.org/10.1016/j.buildenv.2016.08.038
Date Deposited: 19 Jul 2021 15:55
Last Modified: 16 May 2023 11:02
Cite in APA 7: Boppe, I., Bédard, É., Taillandier, C., Lecellier, D., Nantel-Gauvin, M.-A., Villion, M., Laferrière, C., & 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, 230-239. https://doi.org/10.1016/j.buildenv.2016.08.038

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