Hot Water Pipes Research Articles

Validation of an Enhanced Drinking Water Temperature Model during Distribution

Drinking water temperatures are expected to increase in the Netherlands due to climate change and the installation of district heating networks as part of the energy transition. To determine effective measures to prevent undesirable temperature increases in drinking water, a model was developed. This model describes the temperature in the drinking water distribution network as a result of the transfer of heat from the climate and above and underground heat sources through the soil. The model consists of two coupled applications. The extended soil temperature model (STM+) describes the soil temperatures using a two-dimensional finite element method that includes a drinking water pipe and two hot water pipes coupled with a micrometeorology model. The extended water temperature model (WTM+) describes the drinking water temperature as a function of the surrounding soil temperature (the boundary temperature resulting from the STM+), the thermal sphere of influence where the drinking water temperature influences the soil temperature, and the hydraulics in the drinking water network. Both models are validated with field measurements. This study describes the WTM+. Previous models did not consider the cooling effect of the drinking water on the surrounding soil, which led to an overestimation of the boundary temperature and how quickly the drinking water temperature reaches this boundary temperature. The field measurements show the improved accuracy of the WTM+ when considering one to two times the radius of the drinking water pipe as the thermal sphere of influence around the pipe.

Improvement Plan for Prevention of Safety Accidents in Old Facilities

Recently developed buildings are becoming larger, more complex, and higher-rise. After the announcement of the first new city in 1989, other first new cities were created in Bundang New Town in Seongnam-si, Gyeonggi-do, and Ilsan New Town in Goyang-si, where occupancy began in 1992. Subsequently, second new cities were built in 12 locations in 2003. In 2018, third new cities were announced, including the Wangsuk District in Namyangju-si, Gyosan District in Hanam-si, and Gyeyang District in Incheon. The continued announcement of new cities suggests the existence of old equipment in first and second new cities, necessitating the safety management of old facilities. Among major building facilities, cases of safety accidents have been reported due to aging, explosion of refrigerators, fires from aging water substation facilities, and power outages. In December 2018, an accident occurred in which one person was killed and 20 people were injured when a hot water pipe at the regional heating corporation near Baekseok Station in Ilsan ruptured because of aging. Thus, the aging of facilities is a major cause of safety accidents, and the scale of accidents is also increasing, making it urgent to establish improvement measures to counteract the occurrence of accidents in old facilities. To prevent safety accidents in old facilities, this study intends to contribute to safety accident prevention by presenting a replacement standard for the main facility through facility expert surveys and domestic and international useful prior research life management case studies.

Influence of hot water pipe position on the performance of radiant floor heating systems integrated with PCM

To address the slow heating and low efficiency issues of traditional macro-packed phase change material (PCM) radiant floor heating systems, this study innovatively explores the impact of altering the eccentric positions of hot water pipes within the PCM encasement, based on computational fluid dynamics (CFD) numerical simulations. Starting with a concentric case as a baseline, the investigation extends to six different configurations achieved by displacing the hot water pipes vertically (upward and downward) and horizontally. The analysis encompasses the PCM's thermal state, temperature dynamics, spatial distribution, and heat flux. The results indicate that the arrangement of hot water pipes with upward and horizontal displacements demonstrates a more positive impact on improving the thermal performance of the PCM radiant floor heating system, with the effect becoming more pronounced as the displacement distance increases. Cases with upward eccentric movement of r/4 (where r is the encasement radius) and r/2 reached the optimal floor temperature of 297.15 K faster than the concentric case by 2 h and 3.8 h, respectively, during the heating phase. Cases with horizontal eccentric movement advanced by 0.5 h and 2.5 h, respectively. Cases with horizontal displacements of r/4 and r/2 caused smaller temperature fluctuations and provided greater comfort and energy efficiency than those with upward displacements, with average heat flux values being 4.75 % and 11.82 % lower, respectively. These findings offer theoretical support for the optimization and application of macro-packed PCM floor heating systems.

Heat loss from non-circulating domestic hot water pipes increases water consumption and energy demand

Hot water use in showers is a major contributor to residential water and energy consumption, and associated costs and carbon emissions. This study aims to quantify how heat loss from non-circulating pipes contributes to water and energy consumption in residential showers. Heat loss from pipes was modelled for detached dwellings in Melbourne, Australia, using Monte Carlo analysis to quantify variability. Sensitivity analysis was conducted to identify key factors contributing to heat loss. This is the first study to quantify the variability of the impact of heat loss from pipes into increased water (and hence energy) consumption in showers. Under Melbourne conditions, we predicted that heat loss from pipes contributes approximately 2 to 10 % in average shower hot water consumption. Longer pipes, smaller diameter, longer showers and longer intervals between showers were the primary factors driving additional hot water consumption.

Energy-economic-environmental analysis of a net-zero energy greenhouse with fan-coil units and hot-water pipes: Experiment and modelling

This study analysed the performance of a hot-water pipe (HWP) and fan-coil units (FCUs) in controlling microclimate conditions in a net-zero energy greenhouse (NZEG). The performance of a previously developed TraNsient SYstem Simulation (TRNSYS) model for the NZEG was enhanced to include a crop model and several HWP emission standards, and the improved TRNSYS model was used to analyse heating, ventilation and air-conditioning (HVAC) systems for different greenhouse sizes in the Republic of Korea. Further, an economic analysis was conducted. The model validation showed excellent agreement between the measured and simulated values, with Nash-Sutcliffe efficiency of 0.98. The presence of crop in the simulation model reduced the total heating load by 14.5 MWh and increased the cooling load by 4 MWh. The capacity of the FCU was increased as the outside temperature rose from 33.4[Formula: see text] to 36.4[Formula: see text] in summer, and the diameter of the HWP was decreased from 25A to 10A as the outside temperature rose from −21.7[Formula: see text] to −12.2[Formula: see text] in winter to maintain the greenhouse at the desired temperature of 15[Formula: see text]. Notably, the payback period was reduced by 9 years when the annual savings in heating energy costs and revenue from carbon trading were considered as a part of the net economic cash flow.

One disaster two traumas: Being under rubble and burn injuries in the 2023 Maraş, Turkey earthquakes

IntroductionOn February 6, 2023, two separate destructive earthquakes with magnitudes of 7.7 and 7.5 occurred in Kahramanmaraş, Türkiye. More than 50,000 people lost their lives, and over 100,000 were reported injured. In this study, patients referred to hospitals with burn diagnosis and management of burn wounds following the disaster were evaluated. Material and methodsInformation on burn injury admissions related to the earthquake was collected from all burn facilities in the country within 15 days after the earthquake. The patients' demographics, being under rubble, rescue times, burn causes, grafting procedures, and deaths were recorded. ResultsFollowing the earthquake, burn victims were transferred to the 13 Burn Treatment Centers located in 10 provinces. A total of 191 patients were burned. Among the burn patients, 101 (52.9%) were rescued from the rubble 2–60 h after the earthquake. Eight patients who were hospitalized at the burn centers died. Scalding and flame burns were the most common etiologies. Burned total body surface area, concomitant crush injury, hospitalization, and mortality was higher among the patients trapped under rubble (p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively). Victims who stayed longer time under the rubble required significantly more grafting procedures (p < 0.001). ConclusionIn a literature review, it was observed that there are a limited number of publications reporting earthquake-related burns. In the February, 6 Türkiye earthquake, flame burns were seen due to small fires that occurred in collapsed buildings during the earthquake. And also contact burns and hot liquid burns were seen in earthquake victims trapped under rubble. Bursting hot water pipes, overturned stoves, contact with hot central heating radiators, and heated construction irons caused scalding and contact burns. It is believed that prolonged entrapment may cause delays in burn treatment or lead to deeper burns due to prolonged contact with the burning agent, increasing hospitalization rates. This earthquake once again drew attention to burn injuries that could occur during and after earthquakes, including those that may occur under rubble.

Integrating energy efficiency and health safety in building design: A multi-objective optimization approach to minimize virus transmission risk

This study aims to develop an integrated design strategy for an office building in Tehran, optimizing energy efficiency and minimizing virus infection risk, addressing global challenges such as energy conservation and virus transmission. A multi-objective optimization model is developed to identify optimal design parameters for energy performance and infection risk reduction. Environmentally sustainable materials and energy-efficient equipment, such as solar panels, high-efficiency heat pump systems, and advanced air filtration techniques, are employed. The modified Wells-Riley Risk Model calculates infection risk, while energy efficiency is formulated based on the technologies used. Results showcase a significant 14% increase in energy efficiency and a 46% decrease in infection risk compared to traditional building designs, demonstrating the effectiveness of the proposed integrated approach. The optimal design parameters include ventilation rate, the number of solar panels, hot water pipe diameter, and heat pump condenser temperature. This study presents a practical, sustainable solution for designing office buildings that actively address pressing global concerns while fostering healthier, energy-efficient environments. The novelty of this research lies in the development of a multi-objective optimization model that synergizes infection control and energy efficiency, accounting for real equipment parameters and providing a new paradigm for HVAC design. This integrated strategy optimizes decision variables like ventilation rate, filtration level, solar panels, and heat pump operating conditions, offering a comprehensive approach to co-optimize infection control and energy performance.

An analysis of the effectiveness of new generation self-levelling lightweight composite screed for underfloor heating systems

Energy saving has become a significant concern in recent years due to increasing carbon emis- sions and environmental pollution. When examined from a global perspective, it is known that the energy consumed for heating and cooling of buildings is relatively high. In this regard, researchers attach great importance to energy efficiency issues. In recent years, an issue that has been given priority in heating buildings more efficiently is underfloor heating systems. Underfloor heating systems are composite structures of slab concrete, insulation material, hot water pipes, and screed. Here, the thermal performance of the screed is vital as the hot water pipes remain embedded in the screed. This study has produced a new composite and self-leveling screed type that can transfer heat easily. For this purpose, nine screed mixtures were prepared, including a reference (nearly conventional) screed mortar. The screed mortars’ flowability, density, and compressive strength were determined regarding physical properties. Thermal properties, thermal conductivity, specific heat, thermal diffusivity, and heat storage analyses were carried out. In the second stage of the study, a basic underfloor heating system was installed, and the temperatures of the water circulating in the system, the outer surface of the pipe carrying the water, and the outer surface of the screed were measured at specific peri- ods. According to the study results, it has been observed that depending on the thermal prop- erties of the screeds produced within the scope of this study, when used in underfloor heating systems, it can transfer heat from the hot water pipes to the surface with minimum losses.

High-temperature creep behaviors of polybutene-1 with different chain microstructure and molecular weight

The creep resistance of polymer determines the dimensional stability of product under stress. The isotactic polybutene-1 (iPB) with outstanding high-temperature creep resistance and stress-crack resistance is applied widely in the field of hot-water pipes. Although the chain information including weight-average molecular weight (Mw) and aggregate structures of isotactic polybutene-1 (iPB) influence the creep resistance, the crucial factor affecting the creep behavior greatly is unclear. In this work, a series PB samples with varied Mw, isotacticity and configurational sequence were synthesized and characterized based on Gel Permeation Chromatography (GPC), solvent fractionation and Nuclear Magnetic Resonance Spectroscopy (NMR). The Differential Scanning Calorimetry (DSC), Wide-angle X-ray diffraction (WAXD) and Small angle X-ray scattering (SAXS) were used to characterize the aggregation structures of PB samples. The stress-strain behaviors and 95 °C creep deformation of these PB samples were testes by tensile test and Dynamic Mechanical Analysis (DMA), respectively. It was found that these PB samples showed different chain microstructures like 88–99 wt% high isotactic PB (HiPB) fractions, 90–97.6 mol% tetra-meso placements (mmmm) in HiPB fraction, and 50 × 104-160 × 104Mw. Increasing the molecular weight, isotacticity or configurational sequence mmmm enhanced the creep resistance of PB, while mmmm configurational sequence played more important role in creep resistance of PB through adjusting the aggregation structure (crystalline domains) of the final product greatly. Exploring the influencing factors of creep resistance provided guidance for the synthesis of high-performance PB for high-temperature pipe application.

Proposal of detecting for thickness method of hot spring scale inside steel pipes using vibration

At geothermal power plants, there is a problem that hot spring water pipes are blocked by the “hot spring scale”. The hot spring water used for geothermal power generation contains calcium, sulfur, and other substances, and the solid material called the “hot spring scale” adheres to the inside of steel pipes, significantly reducing the efficiency of steam transmission. In addition, there are maintenance costs to remove the “hot spring scale” inside the steel pipes. And it is important to evaluate the thickness of the hot spring scale inside the steel pipe. In this paper, a non-destructive sensor that is evaluated the thickness of the hot spring scale inside the steel tube from the outside of the steel pipe is proposed. The proposed sensor is consisted of a permanent magnet, an alternating excitation coil and an acceleration sensor. The static magnetic field from the permanent, and eddy current inside the steel pipe are generated the vibration in the steel pipe. And the thickness of the hot spring scale is evaluated from this vibration intensity. It is shown that the thickness of hot spring scale from 0 mm to 15 mm can be inspected by this proposed method. In addition, the proposed inspection principle of this inspection method will be clarified by 3-D electromagnetic force analysis and displacement analysis.

Heat Transfer Analysis of Warm Guss Asphalt Concrete for Mini-Trench Overlaying.

Conventional hot mix asphalt overlaying on trench infrastructure typically necessitates extended cooling times for further works and can have adverse effects on buried components, such as electricity cables and hot water pipes. Therefore, this research aims to investigate the use of warm guss mastic asphalt (at an installation temperature of 160 °C) as an overlaying material for mini-trenches, which can reduce the cooling time required for traffic opening and improve the efficiency of the construction process. This research involved two stages: first, lab testing and related research results were used to generate the thermal conductivity and specific heat necessary for simulation work. Second, a finite element model analysis was conducted to evaluate the thermal transmission of the overlaying surface and the buried conduit based on the summer pavement temperature distribution through the Korean Pavement Research Program. Afterward, the field test bed was constructed to verify the simulation. The results indicate that the optimal thickness of the overlaying material and the concrete covering should be designed to ensure thermal durability and meet traffic opening requirements. The overlaying depth of the mini trench using warm mix guss mastic asphalt should be less than 100 mm to meet with the traffic opening time, while the thickness of the concrete covering should be designed to be more than 100 mm to ensure thermal durability. Additionally, the findings suggest that the application of warm guss asphalt could reduce the opening time by 30 min to 1 h and 25 min compared to conventional hot guss asphalt materials. When the pavement surface temperature for the traffic opening is controlled at 50 °C, the asphalt mixture requires at least 2 h to 5 h to meet the cooling criteria for traffic opening, respectively. Overall, this research confirms the potential benefits and optimal use of warm guss mastic asphalt in the construction process of mini-trenches.

Study on Optimization of Copper to Aluminum for Locomotive Finned Tube Radiator

The influence of the improvement of the finned tube radiator unit structure on the fluid flow and heat transfer effect of the locomotive was studied. A saw-toothed fin structure with aluminum instead of copper was proposed to keep the position and size of the flat copper hot water pipe unchanged. CFD simulation analysis was carried out by ICEPAK17.0, under the conditions of an ambient temperature of 24.6 °C, atmospheric pressure of 85,040 Pa and air density ρ = 0.94 kg/m3, to compare the changes of velocity field, temperature field, turbulence field and field synergy angle. The sawtooth structure of the new heat sink increases the turbulence effect of the fluid, reduces the thickness of the outer boundary layer of the water pipe, and strengthens the heat transfer effect of the radiator. Finally, the baffle height, wing window width and sawtooth angle of the sawtooth structure were selected, and the heat transfer coefficient and pressure under three conditions of low, medium and high were used as indexes to analyze the influence of each parameter on the performance of the radiator. The results show that the heat dissipation effect of the serrated aluminum sheet is higher than that of the copper sheet, the heat transfer coefficient is increased by about 1.3%, the average pressure is reduced, the turbulence performance is improved, the synergy angle is reduced by about 2.3°, and the new radiator has better performance. The fin factor has the greatest influence on the heat transfer coefficient and the least influence on the pressure. When the baffle is about 0.15 mm high, the heat transfer coefficient is the largest, and the height change has the highest effect on the pressure. The included Angle factor has the least influence on the heat transfer effect, and the influence on the pressure is higher. By changing the fin window structure, the thermal performance of the finned tube radiator can be improved.

Installation of an ultrafiltration plant in a multi-family house to reduce the hot-water temperature and energy demand: A case study in Germany

Hot-water generation complicates energy efficiency and emission reduction efforts in buildings. High water temperatures are designated for thermal disinfection to prevent human harm from pathogenic microorganisms. Therefore, almost 200 Mt CO2 are annually emitted in the US, Germany and Canada. Heat pumps can replace fossil energies. However, lower temperatures are required to enhance efficiencies.In this case study, the hot-water temperature of the drinking-water installation of a retrofitted multi-family house was decreased by 5 °C to 50 °C. For physical separation of microorganisms, an ultrafiltration plant was installed in the hot-water circulation. To control hygienic safety, microbiological conditions were assessed by laboratory methods such as the cultivation of Legionella spp. and counting of total cells using flow cytometry. The filtrated hot-water was constantly Legionella-free. The cleaning effect of ultrafiltration was 91.15%. Cold-water was not filtrated so that contaminations occurred. As cold- and hot-water pipes (including circulation) are embedded in the same riser strands, temperature transfer occurred promoting bacterial growth. An energy demand calculation revealed that heat losses of the distribution network accounted for 55.25% of the total heat quantity required for hot-water generation. The actual heat up process of water and storage losses constituted 42.74% or 2.01%. Lowering the water temperature by 5 °C saved 7355 kWh yr−1 (equiv. to 1.77 t CO2e yr−1) in this multi-family house. Extrapolation of this case building results in a saving potential of 7.78–14.50 TWh yr−1 (equiv. to 1.87–3.48 Mt CO2e yr−1) in Germany alone, if the energy source is natural gas.

Household flow detection using FEAT (flow estimating accelerometer-thermometer) device

The use of IoT devices in water end use disaggregation verification is an emerging field which offers benefits over conventional approaches, in terms of cost, accuracy and scalability. Having reliably disaggregated water appliance consumption data will enable smart water meter data to be used in household water conservation approaches and for understanding water consumption behaviours. The FEAT device provides a low cost, easily applied and scalable solution that is demonstrated to work even for very low flow conditions of 0.03 l/s. The FEAT device is a combination of a battery, Wi-fi board and MPU6050 sensors providing multi-modal accelerometer and thermometer data. The study places 7 of these FEAT devices onto hot and cold water pipes leading to a shower, which is operated 4 times in a high flow situation, 0.13 l/s, and 4 times in a low flow situation, 0.03 l/s. The data is then analysed and compared with a flow logger to determine if the FEAT device can detect when a domestic appliance is using water. There are limiting cases where the level of noise or external interference limits distorts the data, obscuring the distinguishable peaks in the data due to the similarity of the values. By using high and low pass filtering methods it was possible to enhance the peaks but there are still situations where peaks cannot be detected: for example, if a rigid pipe is not able to vibrate easily or if a hot water boiler is not triggered due to the low flow rate. However, the results show it should be possible to overcome these limiting cases, as it is much less likely for both the vibration and temperature data to be adversely affected by noise or external influences simultaneously, therefore decreasing the effect of noise and external influences. In conclusion, this research paper demonstrates that FEAT devices are a low cost, easily applied and scalable solution for detecting flow. By using high and low pass filtering, placing sensors on freely moving pipes and through the use of multi-modal verification, the FEAT device is shown to work on both metal and plastic pipes even in the lowest flow situations of 0.03 l/s. Therefore the FEAT device is a suitable solution for appliance identification in disaggregation verification datasets.

Experimental and Implementation of a 15 × 10 TEG Array of a Thermoelectric Power Generation System Using Two-Pass Flow of a Tap Water Pipeline Based on Renewable Energy

At the present time, the entire world is suffering from global climate change due to emissions caused by the combustion of fossil fuels. Thus, it is necessary to look for alternative power sources to generate clean electrical energy. Thermoelectric generators (TEG) are one of these alternatives. They convert thermal energy into useful electricity. There are many thermal energy sources such as hot water pipes. The current paper aims to convert waste heat from solar water-fed hot water pipes into electricity using a TEG panel made from 15 × 10 TEG modules. A pipe through which hot water flows serves as the hot side of the panel. The cold side of the panel is cooled using normal tap water. The maximum recorded temperature difference is 42.35 °C which yields an open-circuit voltage of 15.3 V. The maximum efficiency of the panel is 2.1% with an average energy production of 1.435 kWh. This proposed novel TEG panel system can be used continuously day and night. This is in contrast to a solar system, which operates only during the day, as it relies solely on solar radiation.

Parametric sweep simulation for greenhouse temperature field optimization: An Italian case study

The increasing importance of protected cultures in the last decades has led to the definition of aims for greenhouse design and functioning, in order to conjugate productivity and environmental sustainability. In particular, the optimization of greenhouses is finalized to better solar radiation adsorption and ensure to the crops a homogeneous temperature field for the whole growth time. An Italian case study is presented in this paper: the studied farm needs to project greenhouse geometry and design a hot-water pipes heating system to cultivate basil during the winter season, improving the exploitation of natural resources. A simulative analysis has been carried out by mean of COMSOL Multiphysics software, investigating the effects of greenhouse height, number of pipes and water temperature of the heating system on the inside temperature field through a parametric sweep approach. Twenty-seven scenarios have been simulated and three of them have been considered suitable for the farm applications. The simulative approach allows to collect data about the minimum number of pipes, the sensitivity of the internal temperature field to the outside temperature fluctuation (referred also to the height of the greenhouse) and the more suitable heating water temperature needed to ensure the required habitat to the basil crops, minimizing also temperature fluctuations.

Optimization insulation thickness and reduction of CO2 emissions for pipes in all generation district heating networks.

District heating systems are provided solutions for the increasing energy problems in high-population cities. Energy costs go up depending on increasing heat loss in DHS's distribution network. Heat loss from the network consists of 5-20% of transferred energy, and this loss is higher than the other losses in the heating system. In the study, heat losses from the pipes such as supply-return pipes, hot water and circulation pipes into heat canals are investigated based on energy, exergy, economic and environmental. Optimum insulation thicknesses, energy savings, reduction of CO2 emissions, the first investment costs and payback periods of the pipes in the network of all-generation district heating systems are investigated by using Life Cycle Cost Analysis (LCCA) method for fuel types like natural gas, fuel oil and coal. Optimum insulation thicknesses are calculated for different nominal sizes of pipes and various insulation materials such as glass wool, and rock wool for the different climatic zones. According to the results of the study, the heat losses from pipes in the 4th generation DHS network are decreased between 38.19% and 33.33% from the warmest climate zone to the coldest climate zone according to the 3rd generation. Energy savings, reduction of CO2 emissions, payback periods and optimum insulation thickness values of supply and return pipes in the network are respectively changed between 7.80-98.86 $/m, 39.61-322.32 kg CO2/year, 0.028-0.38 years and 0.025-0.0105 m depending on various fuel types, insulation materials, nominal size pipes, climatic zones and all generation types.

Automatic fault diagnosis algorithm for hot water pipes based on infrared thermal images

In recent years, scholars have completed many studies on the fault diagnosis of air-conditioning systems based on Building Energy Management System (BEMS) data, but these studies seldom cover the leakage of water pipes and the damage of insulation layer, that are common but undetected by BEMS. To fill in the gaps, an automatic diagnosis algorithm based on infrared thermal images is proposed here to detect fault occurs on insulated heating pipes. This method can automatically diagnosis of pipeline leakage and insulation damage, so as to prevent pipeline corrosion and heat loss. The algorithm includes two sections: an image segmentation processor and a fault diagnosis module. The fault diagnosis module can detect three categories of faults: insulation damaged, insulation fall-off, and pipeline leakage. Experimental study demonstrates that the overall accuracy of the algorithm is 97.59%, while filed studies in commercial buildings exhibits an accuracy of 92.74%. These data prove the algorithm's feasibility in practice and the method can be applied with an infrared camera installed on an inspection robot or at a fixed location in a machine room. Although images of hot water pipes are used as inputs of the research, this method is also applicable to cold water pipes by modifying relevant parameters.

Design and implementation of a thermoelectric power generation panel based on the temperature difference hot and cold tap water pipes

Design and implementation of a thermoelectric power generation panel based on the temperature difference hot and cold tap water pipes

Investigating Bacterial and Free-Living Protozoa Diversity in Biofilms of Hot Water Pipes of Apartment Buildings in the City of Riga (Latvia)

Background: Biofilms, when formed on the surfaces of water pipes, can be responsible for a wide range of water quality and operational problems. We sought to assess the bacterial and free-living protozoa (FLP) diversity, in relation to the presence of Legionnaire's disease-causing bacteria Legionella pneumophila (L. pneumophila) in 45 biofilms of hot water distribution system pipes of apartment buildings in Riga, the capital city of Latvia.Results: 16S rRNA amplicon sequencing (metataxonomics) revealed that each biofilm contained 224 rather evenly distributed bacterial genera and that most common and most abundant were two genera, completely opposites in terms of their oxygen requirements: the obligately anaerobic Thermodesulfovibrio and the strictly aerobic Phenylobacterium. Water temperature and north-south axis (i.e., different primary water sources) displayed the most significant effect on the inter-sample variations, allowing us to re-construct three sub-networks (modules) of co-occurring genera, one involving (potentially FLP-derived) Legionella spp. Pangenome-based functional profile predictions suggested that all three may be dominated by pathways related to the development and maintenance of biofilms, including quorum sensing and nutrient transport, as well as the utilization of various energy sources, such as carbon and nitrogen. In our 18S rRNA amplicon sequencing data, potential hosts of L. pneumophila were detected in 11 out of 12 biofilm samples analyzed, however, in many cases, their relative abundance was very low (&amp;lt;1%). By validating our findings using culture-based methods, we detected L. pneumophila (serogroups 2, 3, 6 and 9) in nine (20%) biofilms, whereas FLP (mostly Acanthamoeba, Vahlkampfidae and Vermamoeba spp.) were present in six (~13%) biofilms. In two biofilms, L. pneumophila and its potential hosts were detected simultaneously, using culture-based methods.Conclusions: Overall, our study sheds light on the community diversity of hot water biofilms and predicts how several environmental factors, such as water temperature and source might shape it.