【 Weak current College 】 community water supply and sewerage and water heating, water supply---the fifth section of hot water supply system

This section from the hot water supply system of classification, characteristics, composition and selection of a heat source, a hot water quota, temperature, water, hot water heating and heating supply, equipment, network layout and laying a more detailed introduction, this part of the study should focus on mastering the good hot water supply system of classification, heat source selection, hot water heating and hot water supply and pipeline layout requirements. 　　At the same time, it is necessary to pay attention to hot water in the transportation process-specific need insulation measures. First, the hot water supply system overview 1. hot water supply system of classification and characteristics
Hot water supply system characteristics apply to the local hot water supply system, water supply range small decentralized hot water preparation (usually near the water point set small heating equipment for one or more distribution points), the hot water pipes, heat loss is small, the use of flexible hot water consumption, smaller and more dispersed construction, such as modular houses, hospitals, clinics and layout more dispersed workshop and toilet building supply centralized hot water supply system, hot water in a large range of boiler room or heat station set preparation, pipeline transportation to a building or building use, hot-water distribution systems are complex, the equipment more — time of large investment requirements, energy consumption during use, the water point more and more concentrated in construction, such as advanced residential buildings, hotels, hospitals, nursing homes and Stadium and other public buildings in regional water supply system, water supply range in regional boiler house with hot water or heat station through municipal hot water preparation, sent to the entire complex pipe, hot water supply complex, heat loss, equipment, accessories, automated control of advanced technology, management level is high, the one-time investment of large urban areas, within the scope of the residential community
2. the composition of the hot water supply system of hot water supply system in architecture, centralized hot water supply system application more general, the system usually consists of the following. (1) of the first cycle (hot water preparation system)
Also known as htm system, from sources of heat, water heaters and heat supply network. Boiler production of steam (or hot) passed boilling pipeline to the water heater, heat surface heating in cold water. Steam after heat becomes more pressing the frozen water, hydrophobic condensation tank, flow-condensation water and the new add cold water through condensation water circulation pump and then sent back to the steam boiler production. Such a cycle and complete water heating, hot water preparation process.

(2) the second cycle (hot water supply system)
By hot water distribution network and back to the water pipe network. Been heated to a temperature of hot water design requirements, from the water heater exit the water distribution network to each hot-water distribution points, and water heater need cold water from the high water tank or water distribution network. To meet the hot-water distribution points any time the temperature of hot water design requirements, risers and horizontal stem pipes or even water distribution pipes on the return pipe, a certain amount of hot water in the water distribution network and back to the water pipe network flows to compensate for the lost water distribution network, to avoid the heat of the hot water temperature decreases.

(3) Annex
Annex: temperature thermostats, safety valve, pressure relief valve, trap, the expansion tank (carton), pipe automatic compensator, gate valves, faucets and auto exhaust, etc. 3. heat and hot water supply system heat source select currently often used gas, fuel oil and coal as a fuel, boiler output steam or superheated water. Conditions should make full use of geothermal energy, solar energy, industrial heat recovery and heat. 　　Of course, the choice of the heat source must take account of local conditions, economic, technical and safety, and other factors. Second, the hot water quota, water temperature and water 1. hot water quota hot water quota in two ways: first, according to the nature of the use of a building and the improvement of internal health apparatus, with the number of units to determine the temperature calculation by 60 ℃; the second is based on building use properties and internal health units water consumption to determine that health apparatus 1 and l-hour hot water quota, with the function of health equipment, water temperature requirements are also different.　　Production of hot water quota should be based on requirements to determine the production process. 2. the temperature of the water temperature has two meanings: one is the hot water temperature and the temperature of hot water supply. (1) hot water temperature
Domestic hot water temperature should meet the needs of domestic use. However, when in the design of a hot water supply system, you should determine the most adverse of hot-water distribution point so that it is the minimum water temperature and water mixed to achieve domestic hot water temperature requirements, and as a design calculation parameters.
Production of hot water, water temperature should be determined according to the technological requirements.

(2) hot water supply temperature
Hot water supply temperature generally refers to the hot water boiler or water heater outlet water temperature, water temperature too low or too high will cause adverse effects. Hot water boiler or water heater outlet water temperature and water distribution system is the most negative point of water temperature difference, known as the temperature drop value, generally 5 ° c to 15 ° c, used for hot water supply system and water distribution network for heat dissipation. Temperature drop value selection should be based on system size, insulation materials, conduct economic and technical comparison.

(3) chilled water temperature calculation
Hot water system of calculation using cold water temperature should be based on local surface water or groundwater is the most average water temperature of the coldest month. 　　No data available to determine the appropriate form. 3. water quality (1) the water quality requirements for hot water
Domestic hot water should be consistent with our existing standards for drinking water.
Production of hot water should be determined in accordance with the requirements of the production process.

(2) centralized hot water supply system is heated water requirements
Water heating and heating precipitation of calcium and magnesium ions, equipment and pipeline scaling, the dissolved oxygen in the water will accelerate metal precipitates tubes, corrosion of equipment. 　　 　　In General, the daily water consumption is less than 10m3 (at 60 ° c) water supply system, heating water may not be processed on the day of water quality; water of not less than 10m3 (at 60 ° c), and raw water hardness greater than 357mg/l, laundry with hot water treatment should be conducted for other purposes should also be of hot water treatment. Currently, centralized hot water supply system often used electronic descaling, electrostatic cleaner and super strong magnetic water treatment plant etc. TheseUnit volume is small, reliable performance, easy to use. 　　Oxygen equipment was also in some heavy water used in the high buildings. 3. hot water heating and hot water supply way 1. heating hot water heating principle characteristics of direct heating method, also known as a heat exchanger, use gas, fuel oil, coal-fired water boiler for fuel, the cold water directly heated to the required water temperature or high temperature steam or water through a perforated tube or direct contact with the cold water injector hybrid hot water preparation equipment is simple, high thermal efficiency, energy, noise, high requirements to htm, quality is not allowed to cause water pollution that heating method only applies to high-quality noise-medium, not strict, or regular supply of hot water of a public bathroom, laundry room, industrial and mining enterprises, and other user indirect heating method is also called the second heat, use htm through water heaters heat is transferred to the cold water, cooling water heated to the required water temperature noise small, heated water pollution, operational security and stability requirements applicable to the security and stability of the noise low water supply in the hotel, houses, hospitals, office buildings and other buildings
2. hot water supply (1) open and closed
Open the way for hot water supply in hot water distribution system is generally provided by open-water tanks at the top of the tank set height required by the system, pipeline pressure and atmospheric. As user demand for water, outdoor water supply network pressure fluctuation is large, the use of open-type hot water supply. Closed-type hot water supply management simple, water pollution is not vulnerable to the outside world, but the safety relief valve easy failure, poor reliability. Regardless of the way, you must resolve the water heated volume expansion in order to guarantee system security.

(2) not a loop, a half-circle, full loop
No circulation of hot water supply by means of hot water supply system of hot water distribution network level dry pipe, tube and water tube are not set up any circular pipe; half circular hot water supply by means of hot water supply system only in hot water distribution network level dry pipe located circular pipe, the more applicable to a full-day supply of hot water and hot water supply in construction and timing of buildings; total circulating hot water supply by means of hot water supply system of hot water distribution network level dry pipe, risers, even water distribution pipes are equipped with circulating pipe. The system the circulating water pump, water is not used before water and wait time, apply to the superior hotels, hotels and residential buildings of high standard.

(3) return the same program,
With the program refers to each hot water circulation loop lengths are equal, the same as the corresponding pipe diameter, all loops of the same head loss; return refers to each of the hot water circulation loop lengths are not equal, corresponding to the diameter of the pipe is not the same, all loop head loss is not the same.

(4), mechanical natural circulation loop
How is the use of the natural cycle of water distribution and the return pipe in the water temperature of the pressure difference, so that the network to maintain certain cyclic flow to compensate for heat loss in the distribution pipeline to ensure that users on the hot water temperature requirements, and such manner suitable for hot water supply system is small, the user on the water temperature requirements not strictly; mechanical circulatory system is in the backwater dry pipe on circulating water pump, forcing a certain amount of water in the pipe network loops to compensate for heat loss in the distribution pipeline to ensure user requirements for hot water temperature, in such manner applicable to large, and the user on the hot water temperature demanding hot water supply system.

(5) full-day supply, regular mode of supply
Full-day supply, refers to the hot water supply system for the pipe network in any moment throughout the day to remain below the circular flow of water, hot water distribution network throughout the day, any moment can be equipped with water, and water temperature; timing modes of supply, refers to the hot water supply system of water distribution, every day scheduled for the rest of the system stops running, the way in focus, use the circulating pump will supply has been cooling water heated by forced circulation, reach the required temperature is used. 　　　　　　 　　　　 　　Two different ways, in circulation pump selection calculation and management are different.　　Hot water for heating and hot water supply by different criteria for classification, but a complete hot water supply system, is bound by the heating method and supply modes selected combination of an integrated system, shall be based on existing conditions and require reasonable combinations, determine the right programme. 4. heating device type hot water supply system, the design of the cooling water heated to the required temperature of hot water, the device is called a heating device. Hot water supply system of heating with a heat exchanger (direct heat) and the secondary heat exchanger (indirect heat). A secondary heat exchanger is the heat source to room temperature water through a one-time heat reaches the required temperature of hot water, the main heating device has a gas water heater, water heater and coal-fired (oil, gas), water boiler, etc. Secondary heat exchanger is the heat source for the first time Mr. outputs htm (saturated steam or hot water), htm and then through the heat exchanger with a second hot-swap, its main equipments are volumetric water heater, rapid-type water heater, water heater and in special half half that is hot-water heater, etc.　　Specific: ① ② coal-fired hot water boiler; fuel oil (gas) hot water unit; ③ electric heater; ④ volumetric water heaters; ⑤ quick type water heater; ⑥ half volumetric water heaters; ⑦ half that is hot-water heater; ⑧ solar water heater, etc. 5. heating equipment selection and layout (1) heating device of choice for heating equipment should be based on the use of characteristics, heat loss, heat, maintenance management and health factors such as anti-bacteria.　　It should have high thermal efficiency, good effect of heat, energy, fuel combustion safety, smoke and dust removal, unit water jacket-atmosphere, automatic control temperature and flame sensor and automatic alarm function, and to consider saving equipment room, ancillary equipment is simple, small head loss, to the entire system and hot water balance and structure is simple, safe and reliable, easy operation and maintenance, etc. When you use self-provided heat source, the use of a direct supply of hot water heated by oil, gas hot water unit. You can also use secondary heating indirect supply of hot water with the heat exchanger unit, or external with positive displacement, half-volumetric water heater for hot water unit. Indirect heating equipment selection should be considered in conjunction with water thermal storage tank of uniformity,Accumulation, water-supply water hardness, heat supply capacity and systems for cold and hot water pressure balance and stability requirements, the integrated technical and economical comparison. When using steam or hot water as the heat source, conditions permitting, should, as far as possible, using industrial waste heat, heat and geothermal.　　Heating equipment for the use of diversion-volumetric water heater, water heater-positive displacement; if adequate and reliable heat sensitive temperature regulation device, or half that is hot-water heater, rapid-type.　　In the absence of steam, hot water, heat and unconditional use gas, fuel oil and other fuel, and power and plenty of places you can use the electric water heater.　　When the heat source is the use of solar energy, the use of set heat pipe vacuum tube solar water heater or. 2. heating equipment of heating equipment layout positioning must meet the relevant specifications, product samples, etc. ① high pressure boiler is located in the residential and public buildings, set in a separate building, or the candidates have to fire, boiler monitoring and environmental protection departments. ② fuel, gas boilers should be consistent with the relevant provisions of the fire code. ③ water heating equipment and storage devices can be set in the boiler room or single room, room size should guarantee access to and maintenance of equipment, the spacing between devices, pedestrian passageway of the waterway, and shall meet the requirements of ventilation, lighting, lighting, fire and water, and other requirements. ④ htm piping layout, condensate pipeline and condensate pump condensate tank, location, elevation should meet the requirements of the first cycle, hot water storage tanks, expansion pipe and cold water tank location, elevation, the water treatment plant location, elevation, hot water outlet location, elevation, desirable and hot water distribution network. All pipe diameter hydraulic calculation shall be determined. ⑤ volumetric, diversion of positive displacement, half-volumetric water heater side should have not less than the width £ 0.7m channel, front end should be left out of the location of the heating coil. ⑥ water heater the highest point of the upper attachment to the lowest point of the building structure, net margin maintenance requirements should be met, but should not be less than 0.2m, room height shall be not less than 2.2m. ⑦ hot water unit layout should meet the installation, operation and maintenance requirements, its front should stay out of not less than 2/3 units of length, rear stay 0.8 ~ 1.5 m of space, both sides of the channel width, the width for the unit, and not less than 1.0m. 　　Sets the top part (chimney) to the lowest point of the roof is not less than the net margin 0.80m.　　6. hot water pipe network layout and installation 1. hot water pipe network layout arrangement of hot water pipe network may be down or up on to the next to type, in order to meet the entire hot water supply system, water temperature uniform, according to the same program for network layout. Hot water supply system in high-rise buildings, and cold water supply system, take vertical partitions, so as to ensure the system's cooling, hot water pressure balance, easy to adjust the cooling, hot water outlet temperature of mixed mixer, and requirements for the water heater and water for the water will be subject to the same area of water supply system.　　If you need decompression, and decompression of conditions and the specific measures and cold water-supply system in high-rise buildings. 2. hot water pipe laying laying of water pipe network, according to the requirements of the building, you can use Ming installed and concealed two forms. Ming installed as laying in the bathroom, kitchen, and along the walls, beams and columns.　　Concealed duct may be laying in the pipeline trench silo or reserved. 3. hot water pipe insulation and anticorrosion in hot water system, in order to reduce the media in the transportation process of heat loss, avoid reduce hot water preparation, heat circulating flow, improving the long-running economy, piping and equipment for thermal insulation.　　Insulation material choice to follow the principle that the low thermal conductivity, high thermal stability, non-corrosive metal, material density small and have good porosity, low water absorption and a certain mechanical strength, ease of construction, using local materials and low cost. In order to avoid oxygen, carbon dioxide, sulphur dioxide and hydrogen sulfide corrosion on hot water distribution system, and undermine the metal pipe and equipment exterior coating of metal anti-corrosion material, and the pipe inner wall of the device in resistant lining or coloured coating to prevent corrosion. Common corrosion-resistant materials for paint, it is divided into primer and topcoat. Primer on metal surface scratch coat, with attachments, waterproof and rust, paint up light, water and cover.