Everything you need to know about the closed DHW system

Knowing the ins and outs of your heating system is essential to maintaining a warm and cozy home. A closed domestic hot water system (DHW) is a vital part of many home heating systems. However, what is it precisely and why is it relevant? Let’s dissect it.

To begin with, DHW is an acronym for domestic hot water. Put simply, it’s the hot water that emerges from your faucets for regular household chores like dishwashing and bathing. Now picture a closed loop in your heating system that is only used to effectively heat this water. In a word, that is the closed DHW system.

However, what makes this closed system important? To begin with, energy conservation and efficiency are key. You can make sure that your water maintains a constant temperature without needless heat loss or fluctuations by keeping the hot water loop isolated from the rest of your heating system.

Reliability is yet another important advantage of a closed DHW system. It functions separately from the primary heating system in your house, so problems or maintenance requirements with one won’t always impact the other. This implies that your hot water supply won’t be interrupted as much when you need it.

You may be asking yourself now, just how a closed DHW system functions. Basically, to maintain the efficient flow of hot water, a system of pipes, a boiler or water heater, and occasionally a circulation pump are needed. Together, these parts function as a single unit to give you consistent hot water throughout your house.

Network diagrams

Thus, let’s begin by discussing how hot water—that is, water—enters our houses. Pumps installed as boiler equipment move it from the boiler house to the house. The pipes, also known as heat pipes, are used to transport the heated water. They can be put in underground or above ground. Additionally, they must be insulated in order to minimize coolant heat losses.

Scheme for circular connections

The pipe is brought to the apartment buildings, from where the route is branched into smaller sections that supply the heat carrier to each building. The smaller diameter pipe enters the basement of the house, where it is divided into sections that deliver water to each floor, and already on the floor to each apartment. It is clear that such a large amount of water cannot be consumed. That is, all the pumped water in the DHW cannot be consumed, especially at night time. Therefore, another route is laid, which is called the return line. It moves water from the apartments to the basement, and from there to the boiler room through a separately laid pipeline. True, it should be noted that all pipes (and return and supply) are laid along one route.

In other words, it appears that the hot water within the home circulates in a ring. It also moves all the time. In an apartment building, the hot water circulates precisely from bottom to top and back again. However, to ensure that the liquid’s temperature remains constant throughout all floors (within a tiny deviation), ideal conditions for its speed must be established, as this has no bearing on the temperature’s actual drop.

It should be mentioned that separate routes for heating and DHW can currently be approached apartment buildings. Alternatively, a single pipe that can withstand temperatures of up to +95C will be supplied and split between the house’s basement hot water supply and heating system.

Distribution Scheme for DHW

Please take note of the picture above. This plan calls for installing a heat exchanger in the building’s basement.

This indicates that the hot water supply system does not use mains water. All it does is warm the chilly water that comes from the water supply system. Furthermore, the route from the boiler house is not connected to the domestic hot water system itself, which is a different route.

There is a house network in use. Additionally, a pump that is installed in each apartment provides the water supply. This plan is the most up to date by far. The ability to regulate the liquid’s temperature range is one of its advantages. It should be noted that apartment building hot water temperatures are governed by stringent regulations. In other words, it shouldn’t be above +75C or below +65C. Variations of up to 3C are permitted, but not larger ones. Deviations can even reach 5C at night.

Why this temperature

There are two causes.

• The higher the temperature of water, the faster it kills pathogenic bacteria.
• But we have to take into account the fact that high temperature in the DHW system means burns in contact with water or metal parts of pipes or faucets. For example, at a temperature of +65C a burn can be received in 2 seconds.

Water’s temperature

It should be mentioned, incidentally, that a variety of factors can affect the temperature of the water in an apartment building’s heating system. However, it shouldn’t go above +95C for two-pipe systems and +105C for one-pipe systems.

Take note! The law states that 10% of the payment is withheld if the water temperature in the district heating water system is 10 degrees below average. A 30% discount is applied to the payment if the temperature is expected to be between +40 and +45C.

In other words, it appears that an apartment building’s water supply system, or HTW, uses a customized method of payment based on the coolant’s actual temperature. But as experience has shown, very few people are aware of it, so disagreements on this matter almost never occur.

Dead-end circuits

In the DHW system, there are also so-called dead-end schemes. In other words, water is supplied to users, and when it is not used, it cools down. As a result, the heat transfer medium is greatly overused in these systems. These floor plans are utilized in service buildings or modest homes with no more than four stories. Nevertheless, all of this is history now.

Circulation is the best choice. The easiest is the riser pipe that goes through every floor and enters the basement before connecting to the apartments. Every entryway has a separate riser pipe. When the riser reaches the top floor, it turns and goes past every apartment before entering the basement, where it is discharged and joined to the return pipeline.

Dead-end plan

The importance of the temperature regime of hot water

It is important to keep an eye on the hot tap’s water temperature for both economical and epidemiological safety reasons.

This is particularly important for young children, the elderly, people with disabilities, and other citizen groups. The water temperature shouldn’t deviate from the established norms by more than the maximum amount, either in a smaller or larger direction, in order to protect citizens’ lives and health.

In addition to being comfortable, water that is within accepted standards protects citizens’ health and safety from diseases.

The water’s temperature can occasionally—though it does so infrequently—significantly rise above the accepted standards. This deviation puts the skin at risk for thermal damage.

To prevent this, you should be aware of the following effects that hot water at a particular temperature can have on the skin:

• +50°C – if the skin is exposed to water of this temperature for more than 1.5 minutes, minor thermal burns may occur;
• +55°C – when exposed to water of this temperature, skin burns can occur within 15 seconds;
• +60°C – thermal damage to the skin will occur if exposed for 5 seconds;
• +65°C – severe thermal damage to the skin will occur if exposed for 2 seconds;
• +70°C – when water of this temperature is exposed to the skin, severe thermal damage occurs instantly.

Situations where hot water flows from the tap at a temperature much below the standard are not uncommon. This not only increases its consumption and, consequently, the expenses associated with paying for subpar service, but it also opens the door to the emergence of numerous unfavorable circumstances.

For instance, the most favourable conditions for the life and development of numerous harmful microorganisms that can cause a number of diseases in humans are created in the hot water supply system in the event of a significant drop in water temperature.

It is under these circumstances that legionella bacteria most frequently start to grow. The ideal habitat for its vital activity and reproduction is warm, fresh water. This pathogenic bacteria is a bacillus that is gram-negative and has a maximum size of three microns.

In pipes and boilers, Legionella thrives when the water entering the hot water supply system is underheated.

They consequently start to grow quickly and establish sizable colonies. Thus, there is a serious risk to people’s health.

Warm, fresh water is the ideal environment for these pathogenic bacteria. This is the reason they frequently infect heating systems with low temperatures, where they establish entire colonies.

Numerous illnesses, the most serious of which is pneumonia with multiple complications, can be brought on by Legionella.

In addition to washing dishes with water tainted by underheated water, bathing or showering, and other hygiene practices can introduce this bacteria into your body.

The likelihood of your infection is almost zero when the water is heated to the temperatures determined by current regulations, as this eliminates the bacteria’s ability to survive and grow. Water needs to be heated to at least 80°C in order to be completely thermally sanitized.

Let’s examine the impact of water temperature on Legionella growth and activity:

• At water temperatures below 20°C, the bacterium loses its activity, it stops reproducing, it goes into anabiosis, but it does not die;
• Water temperatures that range from 25 to 45°C are the most favorable environment for this bacterium to live, thrive and multiply;
• If the water temperature remains at 55°C for 6 hours, the bacteria will die;
• If the water temperature is 60°C, Legionella colonies will be killed within 35 minutes;
• When the water temperature rises to 65°C, the bacteria are killed within 2 minutes;
• At a water temperature of 70 to 80°C, there is a complete thermal disinfection of water.

Calculation of the required amount of hot water supply

The required amount of hot water supply must be calculated for both closed and open water supply systems. The computation is carried out based on multiple variables that are defined by the quantity of residents and their way of life in a specific building.

When determining the hot water supply, the following are considered:

• expected water temperature;
• The number of people living in the building;
• operational characteristics of the sanitary equipment;
• Frequency of use of showers, baths and other things;
• The number of bathrooms where hot water is used.

Let’s look at the computation using a typical family of four as an example. For instance, filling a 140-liter bathtub can take up to ten minutes, and during that time, taking a shower uses about 30 liters of water. This indicates that the building should receive 170 liters of water at the necessary temperature from the water heater in 10 minutes. The average water consumption is assumed in these computations. The amount of hot water used can differ slightly in real life.

Features of open DHW

The principle of operation needs to be considered when installing an open DHW system. Depending on how the coolant is transported and circulated to the radiators, there are two types of open DHW. Differentiate between open systems that rely on natural circulation and those that employ pumping equipment.

Natural circulation works this way: the open system prevents the presence of excess pressure, so the index is slightly higher at the lowest point because of the hydrostatic action of the liquid column, and at the highest point it corresponds to atmospheric pressure. Naturally, the coolant circulates because of the low head.

Natural circulation works on a very basic principle: colder water with a higher mass and lower temperature displaces hotter water with a smaller mass because the coolant has a different temperature and, therefore, a different density and mass. This is the straightforward justification for the existence of the so-called gravity system. Absolute energy independence is the primary benefit of this type of system, provided that the heating boilers operate in parallel and do not require electricity.

It’s critical to understand! Large diameter and slope are used in the construction of self-feeding pipelines.

Pumping equipment is used in the event that natural circulation is not possible. This shortens the time it takes for the room to heat up by speeding up the coolant flow through the pipeline. The coolant is moved by the circulation pump at a rate of 0.3 to 0 m/s.

Hot water supply in an apartment building

Apartment buildings’ hot and cold water supply systems are created using essentially distinct designs.

A well-designed hot water supply consists of a single or double-pipe riser distribution system, centralized and circulating.

In the first scenario, every riser in a particular area of the building is merged into a single unit, referred to as "idle" because it has no users. To maintain uniform pipe diameters throughout the building and optimize water distribution for every apartment, the risers are looped along the building’s height.

Risers with a specific diameter are made for buildings with varying numbers of floors:

• up to 5 floors – 25 mm;
• 6 floors and above – 32 mm.

The bathroom towel dryer is mounted on the supply riser, which has the drawback that if the boiler room’s water is only moderately heated, it will have already cooled down by the time it reaches the furthest tenants. Experts advise cutting a special jumper pipe (bypass) between the forward and return wiring to prevent such scenarios.

The system has two risers for the supply and discharge of water in the case of a two-pipe distribution. All a diverting circulation riser is when you use a heating elbow to dry towels.

Cold water supply of an apartment building

Apartment building cold water supply pipelines are constructed using a dead-end design, with one branch leading from the water supply source to the final consumer, where the pipeline ends.

A water-metering unit, comprising steel pipes, fittings, and a water meter, is installed at the building’s cold water supply. The meter is first installed so that the arrow on the device’s body and the direction of the cold water flow line up.

The assembly is firmly fastened to the surface (either the wall or the floor), taking care to ensure that the meter’s axis is between 30 and 100 centimeters above the ground. There are metal supports installed where the pipeline turns.

There are metal supports installed where the pipeline turns.

Following guidelines for an apartment building’s water supply

Recall that the relevant building codes and regulations, specifically SNiP "Internal water supply and sewerage of buildings" (No. 2).04.01-85), are taken into consideration when designing the internal water supply of the apartment building.

Important factors influencing the effectiveness of the water supply system’s operation are regulated by this document. There are sections in this SNiP that go into great detail about the details of:

• temperature and other parameters of water in the internal pipe network;
• rules for calculating water consumption depending on the number of consumers and sanitary appliances;
• composition and rules for selecting a cold water supply system depending on sanitary and hygienic requirements, technical and economic feasibility, etc. д.;
• parameters of the hot water supply system;
• diameter for fire water supply, etc.

An actual professional designer can complete the labor-intensive and responsible task of designing an apartment building’s water supply efficiently.

Pipe selection

Pipe replacement is eventually necessary for any hot water supply system, whether it is open or closed. Which pipes are suitable for DHW?

Diameter

All calculations in a system with an open water supply for an apartment building’s occupants are limited to choosing the pipe diameter (connections and risers). Which diameters should be used when doing manual hot water supply plumbing repairs, replacements, or installations?

Steel water supply lines are typically sized DU15. Sizes DU25–DU32 are for dead-end or circulating risers with water points, and DU20 is for idle risers.

Riser systems for water supplies. 25 mm in diameter

It helps to keep in mind a few details when selecting the size of pipes:

1. DN (aka nominal bore) roughly corresponds to the inner diameter of the pipe. Plastic and metal-polymer pipes are labeled with the outer diameter, so their size should be one step larger than that of steel pipes (DN20 instead of DU15 and so on);

The nominal bore for steel pipes and the outer diameter for plastic pipes are specified.

1. When replacing old pipes, the capacity of the new water supply should not be lower than. Simply put, the inside diameter of new risers and connections should be at least as large as the old ones.

Material

For hot water supplied from the elevator station, only metal pipes are permitted (see section "Hot water pipes"). Metal pipe service life). The instruction relates to the well-known instability of water supply parameters: metal-plastic or polypropylene water pipes frequently result in apartment flooding when they overheat or experience hydrostroke.

Breaking of a metal-plastic pipe when the allowed pressure is higher than

Note: The entire cost of the flooding damage will be borne by the tenant if he changed the pipes on his own and used materials not specified in the building’s design.

We highly advise you to examine two varieties of pipes, which are quite different from the black steel pipes you are probably familiar with from Soviet-era homes.

Corrugated stainless steel water supply lines are shown in the picture.

Assessment

We now know what an open hot water supply scheme is. Let us now attempt to compare it with the alternative, which is the closed heat supply scheme (which uses the coolant heat from the heat exchanger to heat water for domestic use).

Advantages

Simpleness and affordability are obvious. There isn’t any sophisticated or costly equipment in the elevator station. Its only maintenance consists of periodic checking of the nozzle size and yearly replacement of the gate and valve valves (it also experiences abrasive wear).

Removed the nozzle and elevator for testing

Disadvantages

Unfortunately, those are far more common.

• Poor water quality. If the water in the HTW system (heated in the heat exchanger in a closed heating system) is potable and must meet the requirements of SanPiN 2.1.4.10749-01, the heating system coolant may contain a large amount of suspended solids, iron oxides and other impurities;
• There is a high probability of water hammer. If circulation in a heating pipe or elevator is stopped quickly (e.g. by turning the lever of a ball valve), the inertia of the water flow will cause a short-term pressure surge at its front;

Hydrostroke’s effects on the DHW system

• Strong influence of human factor on actual water supply parameters. Read more about it.

The temperature and pressure standards are what distinguish open hot water supplies from closed hot water supplies. These match the specifications of the heating pipeline: the water temperature should be between 50 and 75 degrees Celsius, and the pressure should range from 3 to 7 kgf/cm2.

As an example, in a closed heating system, water is supplied at 50–65°C and 1.5–5 kgf/cm2 pressure from the heat exchanger.

However, the DHW system from the elevator unit will receive water from the supply if a careless or lazy plumber forgets to switch DHW to the return with the arrival of cold weather. Remember, this water can heat up to 150 degrees, which is too hot for various types of polymer and metal-polymer pipes, flexible fittings, and rubber gaskets on faucets.

Flexible and plastic supply lines are not very good at withstanding extended overheating.

Dismantling of the sewerage system in the apartment

There are numerous subtleties involved in replacing an outdated sewer pipe that need to be considered during the process. The first step is to identify the pipe’s most susceptible locations for deformation. Additionally, all connections must be disconnected from the pipe, and any debris must be cleared out. All of this is required to guarantee more comfortable work.

The water supply faucet for the apartment is then turned off next to the riser. It is best to cut off the water supply to the entire riser if the replacement will take a long time. The cast iron sewer pipes need to be carefully disassembled at the last minute. Adjustable wrenches and other tools can be used for all of this.

It won’t be feasible to install the new pipe correctly later, so it should be installed as a complete set with a range of adapters and couplings. To stop leaks in the riser, sealant needs to be applied to every connection.

Note: Every fitting and collar needs to be spotless. It is best to use silicone grease made especially for connecting sewer pipes.

Hot water supply

An apartment’s hot water supply is made up of an entire network of pipes and other equipment that heats cold water and provides hot water to users. Sometimes, to heat these types of rooms in an apartment, special pipes are installed in the toilets or bathrooms. They also perform the role of dryers.

Typical layout for a home’s hot and cold water supply system

There are multiple ways to categorize all hot water supply systems:

Systems for supplying hot water locally; centralized systems; networks for heating that are closed or open.

Systems for providing hot water are classified as local or centralized based on how far they can operate.

Local hot water systems

Systems for supplying hot water locally are installed for a single building or a collection of small items. In this instance, the customer heats the water directly. Boilers of the gas or electric flow type heat the water.

These systems are only utilized when centralized hot water supply is not an option, and they need to be maintained on a regular basis.

System for supplying hot water locally

Local hot water systems’ benefit

Minimal heat loss; simple repair; autonomous operation.

Central hot water supply systems

The closure of local and district boiler houses as well as heat supply systems is what led to the development of centralized systems for the apartment’s hot water supply. Central hot water systems will be far more practical in terms of convenience.

An apartment building’s centralized hot water supply system schematic

All of this is predicated on the idea that installing the necessary hardware and extra connections to heat cold water is not necessary. There are drawbacks to this kind of hot water supply system as well. Regular maintenance and repairs are necessary for pipes, but local utilities are rarely able to meet customer demands. This cannot be said of local water supply systems, as there are also significant drops in water pressure and inadequate temperature in the system.

Open or closed heat networks can be used by centralized systems to heat water and deliver it to the user. Open heating networks allow network water to be mixed with water that has already been heated in specialized equipment. The water is then delivered to the customers. Surface-based water heating is accomplished by closed heating networks. There is no physical contact between the water to be heated and the heat transfer medium, which is either steam or superheated water.

Although open heating networks are thought to be more sensible, there may be significant declines in the temperature regime of the water supply. These days, such systems are extremely uncommon.

Closed system for the home’s water and heating

An apartment can supply hot water in a number of ways, including:

A boiler house heats the water before supplying it to the customer. There are designated hot spots in neighborhoods or districts where the water is heated. Specialized equipment installed in the basement of a multi-story building is used to carry out water heating. In the apartment of the customer, water is heated.

The supply of hot water may be running. In this instance, heating is provided by the water that is continuously flowing through the pipes. The water is heated all the time. A dead-end hot water supply is also present. In this instance, the water can just cool down over time rather than being used right away. To heat and maintain the water temperature in the apartment, special tanks have been installed.

It makes sense to use separate hot water supply systems for each apartment in order to save money. The centralized hot water supply has a monthly cost that the user must pay.

Diagrammatic schematic of a water heating boiler

The most cost-effective solution would be to use a boiler to provide hot water for the apartment, since water bills are based on the cold water meter. The customer supplies the hot water on his own.

The equipment necessary for the network to work

A specific set of equipment is needed for the closed district heating and cooling system (closed DHW system), as it is a fairly complex engineering system that must operate continuously and safely.

Water metering station

Water is delivered to the home’s water supply system via it. It has a water flow meter mounted on it. Furthermore, the unit’s design allows for the potential to cut off the water supply while doing planned or emergency pipe fitting repairs. Installed alongside the water metering unit is:

• magnetic or mesh filter of coarse purification;
• cocks and valves through which cold water is supplied;
• measuring devices – pressure gauges, thermometers;
• bypass – bypass pipeline, which is used for the time of maintenance of the water-metering unit.

Of course, a system of pipes is necessary to guarantee the DHW system functions, and these pipes can be categorized into three groups:

Water flows to the risers on the outlets located in the building’s basement. They handle the direct delivery of sanitary supplies, home appliances, towel rails, and other items to the apartments and then route them through intermediaries to the final users. Each group’s pipes are arranged according to a variety of schemes. For instance, water can be supplied to the adjacent apartment through risers installed in one apartment.

Although the pipe diameters are chosen during the building design process, the following measurements are typically followed:

• Sockets from 32 to 125 mm;
• Standpipes from 25 to 40 mm;
• Pipes between 15 – 20 mm.

The following resources are established while creating the project for a closed DHW system:

• metal-plastic;
• pipes made of food-grade stainless steel;
• galvanized pipes.

It is important to keep in mind that metal-plastic pipes can have varying operating temperatures and pressures when placing an order for pipes. It should be noted that dishonest contractors often install pipes and pipe fittings during major repairs that do not meet the specifications of the working documentation.

Advantages and disadvantages of the system

Maximum heat transfer with lowest heat transfer fluid costs is an advantage of the open DHW system. The apparatus is inexpensive on its own, and it doesn’t require the installation of expansion tanks, pumps, or other extras.

The systems have excellent safety and reliability metrics and don’t require any extra funding to operate. Using it has the benefit of making system draining and refilling simple, which is crucial in the summer and winter. It is simple to fill the system and release extra air thanks to the expansion tank.

Leaks notwithstanding, the structure holds together. It is not subjected to high operating pressure, and malfunctions have no effect on it. This also makes filling up the tank simple. Since there’s no need to monitor the maximum pressure, a bucket can be used to top off the tank directly.

It’s important to understand! The fact that the liquid cools down and heats up more slowly with intense discharging is one of the drawbacks. Deaeration and chemical treatment of the water are required in order to make it fit for further use and purification, as the quality of the water in the heat carrier for DHW is far from ideal. It is not possible to use the system during the summer.

Heating the thermal circuit to create hot water is not a financially sensible solution.

The DHW heating medium’s water quality is subpar, necessitating the expenditure of money on chemical and deaeration water purification in order to make it fit for use. It is not possible to use the system during the summer. Heating a heat circuit to generate hot water is not financially viable.

Payment

Last but not least, we will address a few queries regarding the annual increases in heat and hot water rates.

How is the supply of hot water and heating charged?

The amount of heat required to heat water or keep the apartment at a comfortable temperature is the primary factor in determining heating costs. Depending on the area, the cost of heat energy in 2017 ranges from 1000 to 1800 rubles per gigacalorie.

2017 utility rates for the city of Berdsk

The receipts are far more common, though, because heat meters are not installed in every apartment:

• Fixed payment for heating a square meter (it is calculated as a product of the heat consumption norm for a given region and the price of a unit of heat energy);

Simplified plan: the heated area meter is used to determine the heating costs.

• The cost of a cubic meter of hot water including the meter (90-170 rubles per cube).

How can you reduce your heating costs?

To cut expenses, it’s imperative to:

1. Install heat meters on each radiator;
2. Install throttles or thermostatic heads on the supply lines, allowing to limit the flow of coolant through the heater.

The picture shows a sectional radiator with a thermostatic head and heat meter controlling the supply line.

Is it feasible to heat an apartment using the hot water supply?

In a technical sense, sure. It suffices to create a closed heating circuit (such as the most basic one-pipe leningradka) and connect it to the DHW riser’s break for this purpose. You will receive the heat in this manner for free because the riser pipe is free of metering devices.

The most basic heating system is the "Leningradka."

• Any change in the configuration of public utility networks requires approval from the housing organization and, in the case of HTW and heating, from the respective service providers. Obviously, such a change in the heat supply scheme will not be authorized by any of the organizations;
• Unapproved redesign of communications is an administrative offense and is punishable by a fine with an order to restore the original configuration at your own expense;

Uncoordinated redevelopment of communications is regarded as an administrative violation under the Housing Code.

• Finally, and most importantly, you can only disconnect from the central heating system by the entrance or the house, providing a plan for an alternative heating scheme and coordinating it with electricity or gas suppliers (alternative heat sources). Without an official termination of the heating service, you will continue to receive bills, which you want to get rid of.

You must disconnect the heaters from the heating risers and complete an act of disconnection with housing authority representatives in order to cease paying for DH services.

Arranging an open water supply scheme

Any kind of water supply consists of a water source, a pump that raises water, pipelines, manifolds that distribute water through pipes, and an additional water heater installed to provide hot water.

Both open and closed schemes can be used for water supply. The consumer does not have access to the water that is circulated in closed loop circuits, which is the primary distinction between the two types of circuits. It is connected to open devices that are able to consume it. As a result, a water supply must be continuously replenished for an open DHW system. Water is the heat carrier in them.

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Thus, it is imperative that all of the following components be installed correctly when installing an open-type water supply:

1. in order to ensure a uniform and constant supply of water, a pump is installed, with its help the required water pressure is set throughout the scheme. They can be submersible or outdoor. The location of their installation depends on this;
2. To distribute the liquid and heat throughout the house, a pipe layout is installed, through which the coolant will be dispersed;
3. since water from the very entrance to the house is distributed between two schemes – cold and hot water supply, a distribution manifold is installed for this purpose. The wiring scheme will also include taps for consumers – faucets, showers, bathtubs, sinks, etc.д. Their number and placement will depend on the layout of the house and the needs of the occupants;
4. Further for functioning open system of hot water supply requires installation of water-heating device – storage or flow-through, it provides heat supply to the building. The peculiarities of their functioning are explained by their name: the storage first collects water and then heats it, and the flow-through heats it directly in the pipe. For large buildings, one water heater is not enough, so it is usually built a central heating station – a central heating unit, which plays a major role in ensuring the functioning of the heat supply and hot water supply of the house;
5. Various additional devices can be installed for different needs – various automatic devices, filters, relays, etc.д. The number and composition of valves depends on the complexity of the project as a whole.

The type of circulation distinguishes the open system of water supply and heat. The forced circulation scheme is described in the previous section, meaning that a pump is used to move the liquid through the pipe. However, it is also feasible to install a scheme with natural circulation without the need for a pump. Since no electricity is needed to circulate the water, an open hot water supply system with natural circulation has the advantage of being economically advantageous.

Faults

What anomalies in the water supply system’s functioning can the apartment owner fix himself? These are a few of the most common scenarios.

Leaking valves

Leakage on screw valve stems is described.

A typical point of leakage is indicated by an arrow.

• Cause: Partial exhaustion of the gland or wear of the rubber sealing ring.
• Solution: open the valve thimble as far as it will go. The thread on the stem will press the gland from below and the leak will stop.

Noise of valves

Description: There is a loud noise and a vibration of the faucet when you open the hot or (less frequently) cold water faucet. One possibility is that the noise is coming from your neighbors’ faucet.

Loud noises coming from the neighbors’ tap can cause a lot of bad feelings.

Cause: An ongoing series of water hammer attacks is caused by a deformed and crushed gasket on the screw faucet when it is half-open. Its valve, with a split-second interval, closes the seat in the mixer body. The effect is more noticeable on hot water because the pressure is typically noticeably higher.

1. Shut off the water to the apartment;
2. Unscrew the problem tap;
3. Replace the gasket with a new one;
4. Remove with scissors the chamfer at the new gasket. The chamfer will prevent the valve from beating in the turbulent water stream later on.

Changing a screw faucet’s gasket

It should be noted that ceramic faucets do not have the aforementioned issue and are completely compatible with screw threaded ones.

The image depicts a ceramic tap.

Cold towel dryer

• Description: the towel rail in your bathroom is cold and won"t heat up.
• ReasonIf the water supply scheme of a residential apartment building uses continuous circulation of hot water, the culprit is the air left in the jumper between risers after the water has been discharged (e.g. for inspection and repair of stop valves).
• Solution: go to the top floor and ask your neighbors to bleed the air from the jumper between the DHW risers and towel dryers.

If this isn’t possible for some reason, the basement can provide the solution:

1. Shut off the DHW riser pipe passing through your apartment, to which your supply lines are connected;
2. Go up to the apartment and open the hot water taps to the full;
3. After all the air is out of the riser through them, close the taps and open the tap on the riser.

The riser can be directly bypassed from the basement if a discharge pipe is installed.

A small detail: there might not be any pressure difference between the heating system’s strings right after the heating season ends. In this instance, even without air slugs in the risers, towel dryers will remain cold.

The difference between the route’s threads can be zero right after the heating season ends.

Constituent elements of the central water supply system. Types of schemes

Generally speaking, a water supply system includes:

• Distribution duct;
• Water intake design;
• Purification unit.

The water travels a considerable distance straight from the pumping unit to the reservoir before being delivered to the building. The water enters the distribution channel after being thoroughly cleaned and disinfected. Special installations receive a water flow from the distribution channel.

Take note that there are three different types of water supply systems:

• Collector;
• Serial;
• Mixed.

If there are a lot of sanitary appliances in the apartments, collector wiring in the house is frequently utilized. The collector scheme guarantees that all sanitary installations and appliances run steadily.

In this article, we"ll dive into the closed domestic hot water (DHW) system, a crucial component of home heating and insulation. A closed DHW system is a setup where the water used for heating is circulated within a closed loop, ensuring efficiency and minimizing energy loss. We"ll explore how this system works, its key components like the boiler, expansion tank, and circulation pump, and why it"s a popular choice for many homes. From understanding the benefits of this system in terms of energy savings and consistent hot water supply to learning about maintenance tips and potential issues to watch out for, this article aims to provide you with all the essential knowledge you need to make informed decisions about your home"s heating and insulation needs.

Where to start With choosing a water heater

There are numerous ways to supply hot water in a country home. Selecting the appropriate water heating apparatus is crucial. The capacity, power source, and design of water heaters vary. There are many different models of these devices available on the market, but they can all be categorized into two groups:

• flow-through;
• storage.

Based solely on their names, it is already possible to deduce each species’ functional characteristics.

It’s crucial! Tank and flow type gas water heaters are thought to be the most practical. Indirect heating devices also exist, which run on the heat from electric water heaters and heating boilers.

Flow heaters ↑

They do not have a reserve of water and instead heat it continuously. They have very high expectations because of this fact. It is common knowledge that water absorbs a great deal of heat. It takes a tremendous amount of heat energy per unit of time to heat it in real time. Furthermore, a flow heater needs to be able to run practically instantly: turn it on, and hot water starts to flow; turn it off, and the heating stops.

Operation of a standard flow water heater scheme

As an aside, the most obvious example of a flow-through gas water heater is the gas heater that most people are familiar with.

Storage heaters ↑

Organization’s dead-end hot water supply system

Extremely slow to heat a specific amount of water with a single KWh. One drinks heated water when necessary. When the faucet is opened, they also activate instantly, but the power rating will be at its lowest during this period. The overall dimensions of storage water heaters are their only drawback. Should substantial amounts of water be required, the heating tank’s dimensions must be remarkable.

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This is a very popular method for heating water in homes. There are two kinds of heating boilers:

1. Single-circuit – heats only tap water.
2. Dual-circuit – used for both water heating and heating.

Where to go if the hot water is not up to par

The Decree of the Government of the Russian Federation from 06.06.2011.05.2011 г. No. 354 "On Provision of Utility Services to Owners and Users of Premises in Apartment Buildings and Residential Buildings" should be followed if the hot water temperature is below the required level and you wish to obtain recalculation. This document lays out the steps you should take in order.

Let’s quickly review what you should do next:

• If you have found that the temperature of hot water significantly deviates from the norm, you should immediately notify the dispatcher of the management or resource supply company. The notification can be either in writing or verbally;
• The dispatcher, whom you notified about this fact, is obliged to record your appeal;
• In the appeal, which you submit to the dispatcher, clearly state the essence of the problem, specify your surname, name, patronymic and contact information, including address and phone number;
• The dispatcher who received your request is obliged to introduce himself and state his position. After he registers your appeal, you should check with him under which number it is registered;
• If the dispatcher is aware of the causes of your problem, he should inform you about them, as well as the measures that are being taken to eliminate them;
• If nothing is known about the reasons that caused your problems, an appropriate inspection will be carried out upon your request. If necessary, its timing will be agreed with you;
• According to the results of the inspection, an appropriate act should be drawn up. It will record whether the inspection revealed violations, the reasons that led to them, the methodology by which the measurements were made, and other information;
• The above act is drawn up in two copies, one of which is given to you as the applicant, and the second remains in the organization that carried out the inspection;
• In case you are not satisfied with the results of the inspection, you have the right to insist on its repetition with the involvement of independent specialists.

When an impartial specialist participates in an inspection, the time of the inspection should be decided upon in consultation with all parties involved.

The management or resource supply company will pay for this inspection, but you will be responsible for covering all inspection costs if the findings support those of the prior inspection.

What to do once you have the actual document in hand

Once you have the act, which certifies that the hot water temperature is not up to date, you can demand with confidence that the management or resource supply company do a new calculation.

You have every right to file a complaint with the Federal Service for Supervision of Consumer Rights Protection and Human Welfare or to make an appeal to a justice of the peace if, despite your appeal to the dispatcher and, more importantly, the outcomes of multiple inspections, no action is taken to resolve the root causes of the issue.

A little bit about the regulatory framework

Any modern person is well aware that without most public services, including the availability of hot water, life is not comfortable at all. And often the centralized water supply system does not always provide consumers with access to hot water. But if you read the normative documentation, namely sanitary norms and rules (SanPiN) 2.1.4.2496-09, then the requirements for the temperature of hot water in a city apartment will become clear. The temperature limit should not exceed 60 – 75 degrees Celsius. This level is mandatory at all consumer connection points. Maintaining this temperature is necessary to prevent the spread of bacterial and other infections that can harm the health of people living in the house.

How often do you call a plumber?

• The wife fixes everything.
• Everything is fixed by the husband.
• Everything fixes itself.
• From 1 year and more.
• Once a year.

Because JavaScript is disabled in your browser, there aren’t many options for the poll.

• My wife fixes everything. 32%, 655 votes 655 votes 32% 655 votes 32% 655 votes – 32% of all votes
• The husband fixes everything. 29%, 596 votes 596 votes 29% 596 votes 29% 596 votes – 29% of all votes
• Everything fixes itself. 20%, 404 votes 404 votes 20% 404 votes 20% 404 votes – 20% of all votes
• From 1 year or more. 14%, 292 votes 292 votes 292 votes 14% 292 votes – 14% of all votes
• Once a year. 6%, 116 votes 116 votes 116 votes 6% 116 votes – 6% of all votes

Votes in total: 2063 Cast ballots: 2022 January 17, 2018

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• My wife fixes everything.
• The husband fixes everything.
• Everything repairs itself.
• From 1 year or more.
• Once a year.

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Features of a closed system

It is designed as a separate closed circuit for the heat main. Heat exchangers from the CHP mains heat the water inside of it. Here, more pumps are needed. The water is better and the temperature regime is more consistent. The consumer does not remove it from the system; it remains there. Automatic recharge restores minimal water loss.

The heat transfer medium that is provided to the heating system is the source of energy for a closed autonomous system. The temperature regimes for hot water and heating systems are kept distinct.

The system’s drawback is the intricate nature of the water treatment procedure. Water delivery to heat sources that are far apart is also expensive.

Closed DHW system

The idea behind a closed system is this: cold drinking water is heated in a separate heat exchanger after being drawn from the central water supply. It is delivered to the water intake points after being heated.

A closed system has supply and return pipelines that are used to circulate water in a circular manner. It also implies that the heat carrier and hot water operate independently. A system like this will maintain regular pressure even if you use the sink and shower simultaneously. The system’s ease of use in controlling the hot liquid’s temperature is another benefit.

Dead ends and circulating DHW are possible. The supply water pipes are the only components of the dead-end system, and they are connected using the same technique as in the first instance.

The benefit of closedDHW is that it saves money by maintaining a steady temperature. An installation of a towel dryer is feasible. Water heaters are necessary for closed DHW; we will discuss several kinds of them below.

Open system

A coolant that is constantly circulating within the system is what distinguishes an open DHW system. The central heating system is the source of hot water. There is no difference in the quality of water coming from the heating equipment or the tap. It turns out that people use the coolant as a result.

The reason the open system gets its name is because hot water is supplied by the heating system’s open taps. A multi-story building’s DHW scheme permits the use of an open type. This kind is too expensive for private homes.

It should be noted that the open system saves money because the liquid doesn’t need to be heated by water heating devices.

Apartment building water supply rules

It is rare to find a high-rise building in a modern metropolis without a water supply system. Water supply systems for apartment buildings: Today, we will discuss their characteristics and operational principles.

Three universal elements are present in all multi-apartment building houses, even though their systems for hot and cold water supply may differ. They are going to be in every construction. These fundamental components consist of:

The divisions and branches required to supply water to the taps directly in the apartments already; risers, which are installed inside the apartment building and serve to conduct water to the distribution systems; and the mains, or the pipes and systems that carry water from external sources to in-house common risers.

The interruption of the water supply is caused by the breaking of one of the universal elements.

For this reason, it’s critical to comprehend who is in charge of ensuring that each structure operates as intended. The city services, not the management companies, are in charge of fixing any breaks that happen on the main line.

Additionally, city services maintain and replace the trunk lines on a scheduled basis.

The management company is in charge of the communal risers; its representatives should be contacted if there is a problem with this system. There’s a pretty good reason why a lot of apartment building water supply risers are in terrible shape.

First of all, since the riser is situated in each individual apartment, both the residents and the staff of the management company should evaluate its integrity. How many of us check the riser pipe on a regular basis? Not in my opinion.

The management company’s staff should visit each apartment on a regular basis and ask the tenants to show the riser. However, there are two possible scenarios here: first, some dishonest organizations might not ask the tenants to do this, and second, apartment owners might choose to stop the system from being inspected.

Recall that it is critical to report riser pipe malfunctions or replacements in a timely manner in addition to conducting a thorough inspection of the pipe’s state. If not, it might just burst, in which case you’ll have to deal with the flooding of the apartment—likely including your own as well as the one below.

The homeowners are responsible for determining the state of the branches and connections. They swap out these system components on their own or with the help of invited experts from the management company or specialized businesses.

The distribution system, both upper and lower Modern homes typically feature a downstream water supply system. This indicates that water enters the common riser pipe from the basement through the main pipes. Nearly all modern homes have this design since it is the most practical and cost-effective.

Modern metropolitan areas also contain overhead wiring. This construction is unique in that it has an installed special water storage tank on top of the building. Pipes installed inside the house allow water to enter. The common riser is then used to distribute the water to the apartments. Since additional pipes must be installed in addition to the riser—the same pipes that carry water from the main line to the storage tank—the use of this distribution is frequently unnecessary. This raises the price of water supply services, making it unprofitable for the management company as well as the residents.

Although any component of the water supply system is susceptible to failure, the portion of the building that supplies hot water still experiences far more frequent breakdowns. For this reason, megacities still periodically turn off their hot water systems for safety, usually during the summer.

In this period, the services not only verify that the structure is sound, but they also fix any malfunctions. A rust deposit more frequently forms inside the hot water supply pipes, obstructing the flow of water and raising the risk of pipe bursts.

News on the topic

• 27.08.2017 г. Courts on heat energy as part of hot water supply On July 31, 2017, the Arbitration Court of the Moscow District adopted the Resolution on the results of consideration of the cassation appeal against the Decision of the Arbitration Court of the Moscow Region of 12.12.2016 in case No. A41-18008/16, as well as the Decree of the 10th AAC of 17.04.2017, No. 10AP-805/2017 in case No. A41-18008/16, which addressed the issue of the procedure for determining the cost of the component for heat energy used for heating cold water for the purposes of providing a hot water supply (HTWS) public utility service, in calculations by utility service providers with resource supplying organizations.
• 25.07.2017 г. "Observance and protection of citizens" rights in the sphere of housing and communal services" Report of the Commissioner for Human Rights in the Russian Federation. This report was prepared on the basis of Part 2 of Article 33 of the Federal Constitutional Law "On the Commissioner for Human Rights in the Russian Federation" and is devoted to analyzing the situation with the observance and protection of the rights of citizens in..
• 19.07.2017 г. Why drinking tap water has become dangerous for health Nikolay Pavlovich, there is an opinion that in Russia half of the pipes that provide cold and hot water supply, as well as drainage, should be replaced. Is it?

Popular answers to housing and utilities questions

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Drawing up a heat supply scheme

The heat supply scheme is a pre-project document that outlines the legal relationships, operational parameters, and advancement of a city district’s or settlement’s heat supply system. The federal law contains some standards pertaining to it.

1. for settlements are approved by executive authorities or local self-government bodies, depending on the number of population.
2. There should be a single heat supplying organization for the relevant territory.
3. The scheme specifies energy sources with indication of their main parameters (loading, work schedules, etc.).) and radius of action.
4. Measures for the development of the system of heat supply, conservation of excess capacity, creation of conditions for its uninterrupted operation are specified.

As per the approved scheme, the settlement’s boundaries contain the location of the heat supply facilities.

Autonomous heat supply of a residential building

An organized system is built into older structures. Different schemes let you select the kinds of heat supply systems that will save you money on energy. Here, it’s possible that they will disconnect their phone when it’s not needed.

The heating standards are taken into consideration when designing autonomous systems. Without it, the house could not be operated. Comfort for the occupants of the house is ensured by adherence to the rules.

Boilers, whether gas or electric, are typically the source of water heating. Selecting the system flushing technique is essential. Hydraulic systems employ the hydrodynamic method. It is possible to use chemicals for autonomy. In this instance, consideration must be given to the safety of the reagents’ effects on pipes and radiators.

Topic	Everything you need to know about the closed DHW system
Description	A closed DHW (Domestic Hot Water) system is a method of heating water for household use using a closed-loop system. It"s efficient and safe, ensuring hot water is readily available.

In order to maximize their heating and insulation strategies, homeowners must have a thorough understanding of the closed DHW (Domestic Hot Water) system. Improved temperature control, lower risk of corrosion, and enhanced energy efficiency are just a few benefits of this system. A closed DHW system reduces heat loss and keeps impurities out of the system by shutting off the water supply from the atmosphere.

The expansion tank is a crucial part of the closed DHW system because it allows water to expand as it heats up and maintains steady pressure levels throughout the system. Furthermore, by releasing excess pressure, a pressure relief valve is necessary to maintain safe operating conditions. The longevity and efficiency of the system depend heavily on routine maintenance, which includes making sure the insulation is adequate and looking for leaks.

To reduce heat loss, homeowners should give priority to materials with high thermal resistance when choosing insulation options for the closed DHW system. In addition to increasing energy efficiency, proper insulation also contributes to stable water temperatures, which lessens the strain on the heating system and lowers utility costs.

All things considered, the closed DHW system provides a good option for homeowners looking to maximize their insulation and heating tactics. Homeowners can increase energy efficiency, lower expenses, and improve comfort levels in their homes by making educated decisions based on their understanding of its features and advantages.

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🔴 RECIRCULATION. How it works?? #water supply #heating #recirculation #HWS