scholarly journals Forensic Engineering Analysis Of The Negative Effect Of Hot Water Distribution Systems On Heater Operation

2002 ◽  
Vol 19 (1) ◽  
Author(s):  
Edward W. Saltzberg
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Hot Water ◽  
Engineering Analysis ◽  
Water Heater ◽  
Water Heaters ◽  
Negative Effect ◽  
Forensic Engineering ◽  
Construction Defects

Our Office Had Two Condominium Litigation Cases That Had A Number Of Construction Defects. One Was A Luxury Complex And One Was A Moderately Priced Project. However, There Were Two Common Allegations In Both Cases. These Allegations Were That The Occupants Complained That They Did Not Have Sufficient Hot Water And That The Water Heater Was Not Able To Provide A Sufficient Quantity Of Hot Water. We Prepared Calculations On Both Of The Water Heater Systems To Determine If They Were Undersized. The Calculations Determined That The Water Heater Assembly Of Both Installations Were Liberally Sized And Should Have Been Able To Maintain Design Temperature All The Time, Even At Peak Use. To Ensure That The Water Heaters Were Both Operating Correctly, We Had The Water Heater Manufacturer Come Out And Service The Heaters On Both Systems. Both Systems Were Operating Properly.

scholarly journals An Analysis Model for Domestic Hot Water Distribution Systems

2011 ◽  
Author(s):  
Jeff Maguire ◽  
Xia Fang ◽  
Moncef Krarti
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Distribution Systems ◽  
Simulation Software ◽  
Hot Water ◽  
Water Heater ◽  
Domestic Hot Water ◽  
Study Results

A thermal model was developed to estimate the energy losses from prototypical domestic hot water (DHW) distribution systems for homes. The developed model, using the TRNSYS simulation software, allows researchers and designers to better evaluate the performance of hot water distribution systems in homes. Modeling results were compared with past experimental study results and showed good agreement. The model was also compared with existing domestic hot water distribution system modeling software HWSIM for verification. The developed model has several capabilities that are not available in HWSIM, including the ability to integrate any new or existing types of water heater systems, the ability to handle several simultaneous draws to different end uses, and the ability to handle unique annual draw profiles instead of weekly draw profiles. It also allows for draw profiles and ambient conditions to be considered using any time resolution. To demonstrate the abilities of this new model, a series of sensitivity analyses were performed using a benchmark domestic hot water distribution system. The effects of adding insulation to the domestic hot water distribution system of homes with a gas water heater and a solar water heater were also examined.

scholarly journals How Molecular Typing Can Support Legionella Environmental Surveillance in Hot Water Distribution Systems: A Hospital Experience

2020 ◽  
Vol 17 (22) ◽  
pp. 8662
Author(s):  
Luna Girolamini ◽  
Silvano Salaris ◽  
Jessica Lizzadro ◽  
Marta Mazzotta ◽  
Maria Rosaria Pascale ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Molecular Typing ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Gene Sequencing ◽  
Culture Technique ◽  
Hot Water ◽  
Environmental Surveillance ◽  
Risk Map

In this study, we aimed to associate the molecular typing of Legionella isolates with a culture technique during routine Legionella hospital environmental surveillance in hot water distribution systems (HWDSs) to develop a risk map able to be used to prevent nosocomial infections and formulate appropriate preventive measures. Hot water samples were cultured according to ISO 11731:2017. The isolates were serotyped using an agglutination test and genotyped by sequence-based typing (SBT) for Legionella pneumophila or macrophage infectivity potentiator (mip) gene sequencing for non-pneumophila Legionella species. The isolates’ relationship was phylogenetically analyzed. The Legionella distribution and level of contamination were studied in relation to temperature and disinfectant residues. The culture technique detected 62.21% of Legionella positive samples, characterized by L. pneumophila serogroup 1, Legionella non-pneumophila, or both simultaneously. The SBT assigned two sequence types (STs): ST1, the most prevalent in Italy, and ST104, which had never been isolated before. The mip gene sequencing detected L. anisa and L. rubrilucens. The phylogenetic analysis showed distinct clusters for each species. The distribution of Legionella isolates showed significant differences between buildings, with a negative correlation between the measured level of contamination, disinfectant, and temperature. The Legionella molecular approach introduced in HWDSs environmental surveillance permits (i) a risk map to be outlined that can help formulate appropriate disinfection strategies and (ii) rapid epidemiological investigations to quickly identify the source of Legionella infections.

scholarly journals Temperature diagnostic to identify high risk areas and optimize Legionella pneumophila surveillance in hot water distribution systems

2015 ◽  
Vol 71 ◽  
pp. 244-256 ◽  
Author(s):  
Emilie Bédard ◽  
Stéphanie Fey ◽  
Dominique Charron ◽  
Cindy Lalancette ◽  
Philippe Cantin ◽  
...  
Keyword(s):  
High Risk ◽  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Hot Water ◽  
Risk Areas ◽  
Temperature Diagnostic

Occurrence of legionellae in hot water distribution systems of Finnish apartment buildings

1994 ◽  
Vol 40 (12) ◽  
pp. 993-999 ◽  
Author(s):  
Outi M. Zacheus ◽  
Pertti J. Martikainen
Keyword(s):  
Surface Water ◽  
Ground Water ◽  
Water Temperature ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Water Systems ◽  
Hot Water ◽  
Apartment Buildings ◽  
Water Plants

The occurrence of legionellae in the hot water distribution systems of 67 buildings located in different parts of Finland was studied. Most of the buildings were apartment buildings. They had different hot water temperatures, and some received their cold potable water from surface water plants and some from ground water plants. Hot water samples were taken from taps, showers, and water mains just before and after the heat exchanger. Legionella pneumophila was isolated from 30% of the distribution systems. In the legionella-positive samples the legionella concentration varied from < 50 to 3.2 × 105 colony-forming units (cfu)/L (mean 2.7 × 103 cfu/L). The highest concentration of legionellae was found in the shower water. Legionellae appeared more often and with higher concentrations in hot water systems using cold water processed in surface water plants than in hot water systems associated with ground water plants. A high organic matter content in surface waters might favor the occurrence of legionellae and also the growth of other heterotrophic microbes. Mean water temperature just after heating was slightly higher in the legionella-negative systems than in the legionella-positive systems (53.5 vs. 51.5 °C).Key words: Legionella, organic carbon, hot water distribution system, water temperature.

scholarly journals Prevalence of Legionella spp. in hot water samples from Polish hospitals in 2009-2013

2019 ◽  
Vol 73 ◽  
pp. 47-52
Author(s):  
Iwona Gładysz ◽  
Maria Kozioł-Montewka ◽  
Agnieszka Sikora ◽  
Małgorzata Wójtowicz-Bobin ◽  
Jan Karczewski
Keyword(s):  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Microbiological Quality ◽  
The State ◽  
Hot Water ◽  
Epidemiological Surveillance ◽  
Bacterial Counts ◽  
Microbiological Analyses

Background: Microbiological threat from Legionella spp. is associated with the current widespread use of air-condition systems and frequent colonization of hot water distribution systems in public facilities (hospitals, hotels, nursing homes). This poses a particularly high risk in hospitalized patients, as many of them are immunocompromised. More than 50 species and 72 serogroups of Legionella spp. have been described thus far, including more than 20 species being pathogenic to humans. Material/Methods: Microbiological threat posed by Legionella spp. was assessed based on a retrospective analysis of microbiological quality of water from hot water distribution systems in Polish hospitals, determined in 2009-2013 at certified laboratories of the Sanitary-Epidemiological Surveillance. The results were kindly provided by the hospitals’ administration upon request, for which the authors would like to express their deepest gratitude. The study material included samples of hot water from internal distribution systems in 379 Polish hospitals, collected by the State Sanitary Inspectorate. Results: Based on the results of microbiological analyses, we were able to estimate Legionella spp. colonization rates in hospital water distribution systems and to assess the activities undertaken by the State Sanitary Inspectorate to reduce excessive bacterial counts in this reservoir. Microbiological analyses conducted in 2009-2013, i.e. after implementing a statutory obligation to monitor Legionella spp. in hospital hot water distribution systems, showed elevated bacterial counts in 3.92% to 12.7% of the samples. These findings justify further microbiological monitoring of hospital water distribution systems. Discussion: The prevalence of the most pathogenic serotype SG1 in hot water distribution systems of Polish hospitals is relatively low compared to other European countries. To maintain this favorable status, hospital water systems should be monitored not only for the presence of Legionella pneumophila, but also for the prevalence of serogroup 1 L. pneumophila.

scholarly journals Legionella pneumophila’s Tsp is important for surviving thermal stress in water and inside amoeba

2020 ◽  
Author(s):  
Joseph Saoud ◽  
Thangadurai Mani ◽  
Sébastien P. Faucher
Keyword(s):  
Heat Treatment ◽  
Thermal Stress ◽  
Heat Shock ◽  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Water Systems ◽  
Exponential Phase ◽  
Hot Water

ABSTRACTLegionella pneumophila (Lp) is an inhabitant of natural and man-made water systems where it replicates within amoebae and ciliates and survives within biofilms. When Lp-contaminated aerosols are breathed in, Lp will enter the lungs and infect human alveolar macrophages, causing a severe pneumonia known as Legionnaires Disease. Lp is often found in hot water distribution systems (HWDS), which are linked to nosocomial outbreaks. Heat treatment is used to disinfect HWDS and reduce the concentration of Lp. However, Lp is often able to recolonize these water systems, indicating an efficient heat-shock response. Tail-specific proteases (Tsp) are typically periplasmic proteases implicated in degrading aberrant proteins in the periplasm and important for surviving thermal stress. In this paper, we show that Tsp, encoded by the lpg0499 gene in Lp Philadelphia-1, is important for surviving thermal stress in water and for optimal infection of amoeba when a shift in temperature occurs during intracellular growth. Tsp is expressed in the post-exponential phase but repressed in the exponential phase. The cis-encoded small regulatory RNA Lpr17 shows opposite expression, suggesting that it represses translation of tsp. In addition, tsp is regulated by CpxR, a major regulator in Lp, in a Lpr17-independent manner. Deletion of CpxR also reduced the ability of Lp to survive heat shock. In conclusion, this study shows that Tsp is an important factor for the survival and growth of Lp in water systems.IMPORTANCELegionella pneumophila (Lp) is a major cause of nosocomial and community-acquired pneumonia. Lp is found in water systems including hot water distribution systems. Heat treatment is a method of disinfection often used to limit Lp’s presence in such systems; however, the benefit is usually short term as Lp is able to quickly recolonize these systems. Presumably, Lp respond efficiently to thermal stress, but so far not much is known about the genes involved. In this paper, we show that the Tail-specific protease (Tsp) and the two-component system CpxRA are required for resistance to thermal stress, when Lp is free in water and when it is inside host cells. Our study identifies critical systems for the survival of Lp in its natural environment under thermal stress.

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