Determine the consumption of hot water. Water consumption for hot water supply, norms

The second component

In general, the amount of payment for hot water supply is calculated according to the following formula:

P i gv \u003d Vi gv × T xv+ (V v cr × Vi gv/ ∑ Vi gv × T v kr)

Vi Guards- the volume of hot water consumed during the billing period (month) in an apartment or non-residential premises

T xv- cold water tariff

V v cr- the amount of thermal energy used for the billing period for heating cold water at independent production hot water management company

∑ Vi gv- the total volume of hot water consumed during the billing period in all rooms of the house

T v cr- tariff for thermal energy

Calculation example:

Suppose the consumption of hot water in an apartment for a month was 7 m 3. Hot water consumption in the whole house - 465 m 3. The amount of heat energy spent on DHW heating according to the common house metering device - 33.5 Gcal

7 m 3 * 33.3 rubles. + (33.5 Gcal * 7 m 3 / 465 m 3 * 1331.1 rubles) \u003d 233.1 + 671.3 \u003d 904.4 rubles,

Of which:

RUB 233.1 - payment for actual water consumption (DHW line in the receipt)

671.3 - payment for thermal energy spent on heating water to the required temperature (DHW heating line in the receipt)

In this example, 0.072 gigacalories of thermal energy were spent to heat one cube of hot water.

AT a value showing how many gigacalories it took to heat 1 cubic meter of water in billing period called DHW heating factor

The heating coefficient varies from month to month and largely depends on the following parameters:

Cold water supply temperature. AT different time year the temperature of cold water is from +2 to +20 degrees. Accordingly, in order to heat the water to the required temperature, you will have to spend a different amount of thermal energy.

The total volume of water consumed per month in all areas of the house. This value is largely influenced by the number of apartments that have passed their testimony in the current month, recalculations and, in general, the discipline of residents taking their testimony.

The cost of thermal energy for the circulation of hot water. The circulation of water in the pipes occurs continuously, including during the hours of minimum drawdown. That is, for example, at night, hot water is practically not used by residents, but thermal energy is still spent on heating water to maintain the required temperature of hot water in heated towel rails and at the inputs to apartments. This indicator is especially high in new, sparsely populated houses and stabilizes with an increase in the number of inhabitants.

Average values ​​of DHW heating coefficients for each block are given in the section "Tariffs and calculated coefficients"

With the advent of cold weather, many Russians are concerned about the question of how to pay for utilities. For example, to how to calculate hot water and how often you should pay for these services. To answer all these questions, you first need to clarify whether a water meter is installed in this dwelling. If the counter is installed, then the calculation is made according to a certain scheme.

The first thing to do is to look at the receipt for utility services, which came last month. In this document, you should find a column that indicates the amount of water consumed over the past month, we need figures with indicators at the end of the last reporting period.

The first thing to do is to look at the receipt for utility services, which came last month

After these indications are written out, they should be entered in a new document. In this case, we are talking about a receipt for payment of utility bills for the next reporting period. As you can see, the answers to the questions, how to calculate the cost of hot water by the meter, how to determine its consumption, are quite simple. It is necessary to timely and correctly take all the readings of the water meter.

By the way, many management companies themselves enter the above information into payment document. In this case, you do not have to look for data in old receipts. You also need to remember that in situations where the water meter has just been installed and these are the first readings, the previous ones will be zero.

The initial readings of some modern counters may not contain zeros, but some other numbers.

I would also like to clarify that the initial readings of some modern meters may not contain zeros, but some other numbers. In this case, in the receipt in the column where you need to indicate the previous readings, you need to leave these numbers.

The process of searching for previous meter readings is very important if you need to figure out how to calculate hot water from a meter. Without these data, it will not be possible to correctly calculate how many cubic meters of water were used in this reporting period.

So, before you start studying the question of how to calculate the cost of hot water, you should learn how to take readings from a water meter.

Designations on the counter

Almost all modern counters have a scale with a minimum of 8 digits. The first 5 of which are black, but the second 3 are red.

Important

It is important to understand that only the first 3 digits are displayed in the receipt, which are black. Because this is the data of cubic meters, and it is on them that the cost of water is calculated. But the data that is colored in red is liters. They do not need to be listed on invoices. Although these data make it possible to estimate how many liters of water a particular family consumes for a certain reporting period. Thus, you can understand whether it is worth saving on this benefit or whether the expense is within the normal range. And of course, you can determine how much water is spent on taking bath procedures, and how much on washing dishes, and so on.

It is important to understand that only the first 3 digits are displayed in the receipt, which are black

In order to correctly understand how to calculate the tariff for hot water, you should know on which day of the month the readings of this device are taken. Here, it must be remembered that water meter data must be taken at the end of each reporting period, after which they must be transferred to the appropriate authority. This can be done through phone call or over the Internet.

On a note! It should be remembered that the figures are always indicated at the beginning of the reporting period (that is, those that were removed last month) and at the end (these are those that are removed now).

This regulation is spelled out in the Decree of the Government of the Russian Federation of 05/06/2011, its number 354.

How to correctly calculate the service?

It is no secret that the legislation of our country is constantly changing, in connection with which citizens begin to worry about the question of how to calculate hot water or any other utility costs.

If we talk specifically about water, then we should take into account the fact that the payment consists of certain components:

• indicators of the water meter, which is located in the room and controls the flow of cold water;
• indicators of the meter, which shows the consumption of hot water in this apartment;
• indicators of the device, which calculates the consumption of cold water for all tenants;
• data of the meter that controls the consumption by the residents of the house, it is installed in the basement of the house;
• the share of a particular apartment in the total expenditure;
• share, which corresponds to a particular apartment in this house.

The penultimate indicator is the most incomprehensible, although in fact everything is quite accessible. It is taken into account when determining the amount of the resource that was spent on everyone. It is also called "common house needs." This, by the way, also applies to the last indicator, it is calculated when general house needs are calculated.

Calculation of hot water consumption

As for the first two indicators, they are quite understandable. They depend on the residents themselves, because a person himself can choose for himself whether to save the consumption of a particular resource or not. But in other cases, it all depends on how often wet cleaning at the entrance of the house, from the number of riser leaks, and so on.

The worst thing about this settlement system is that almost all of the common house needs are fictitious. Indeed, in every house there are tenants who incorrectly indicate their individual indicators, or, for example, one person is registered in their apartment, but five live. Then the general house needs should have been calculated based on the fact that 3 people live in apartment No. 5, and not 1. In this case, everyone else would have to pay a little less. As you can see, the question of how to calculate hot water still needs careful study.

That is why our officials are still trying to figure out how to calculate the payment for hot water and what mechanism would be the most successful.

Does everyone have the same rates?

To save money, you should always screw on the tap, if in this moment no need to use water

To do this, just go to the site of the management company or just call there. Also, such information is contained on the receipt, which comes to each tenant.

After these data are found, the cost of spent cubic meters of the resource should be calculated. Further, it is quite simple to calculate the payment for hot water, this is done in the same way as in the case of all other resources. You should take the number of cubic meters spent and multiply by a specific tariff.

It should be noted that today there are many ways to save hot water consumption, thereby reducing your costs of paying for it. To do this, you can use special nozzles on the faucet, they will help not to spray water so much and control the power of pressure. You should also open the faucet valve not at full strength, so the jet will go under less pressure, but the water will not scatter in all directions. And of course, you should always screw on the tap, if at the moment it is not necessary to use water. For example, when a person brushes his teeth or washes his hair (while the head is being soaped or the toothbrush is being smeared, the water tap can be closed).

All these tips will help reduce the cost of paying for hot or cold water, thereby helping to correctly calculate the consumption of hot water.

The difference between hot and cold water calculations

Of course, in this formula, as in the one that takes into account the consumption of hot water, there are many flaws. Due to the fact that general house indicators are taken into account, it is difficult to control where the difference between the individual indicators of all residents and the data that was taken from the water meter installed on the house went. Perhaps everything really is, and all this water went to clean the entrance. But this is hardly believable. Of course, there are residents who deceive the state and give incorrect data, but there are also errors in the operation of the pipeline system itself (sewer pipes in most houses are old and can leak, so the water goes nowhere).

Hot water invoice

For a long time our government has been thinking about how to correctly calculate hot and cold water and how to improve the existing mechanism.

For example, in 2013, our authorities came to the conclusion that it is necessary to establish standard norms for general house needs and it is these data that should be taken into account when calculating the cost of one cubic meter water. This helped to somewhat restrain the zeal of our management companies and help the citizens of the country. You can find out these figures from the management company. But this applies only to those cases where the tenants have entered into an agreement with the management company. If we are talking about Vodokanal, then each settlement will have its own separate fixed minimum payment. And, let's say, an overpayment in this reporting period can cover expenses in the next one.

As you can see, there is a whole scheme that makes it clear how to calculate hot water heating or how to calculate how much to pay for cold water consumption.

Calculation of the cost of thermal energy for heating 1 sq. meters of total area in 2017:

January-April 0.0366 Gcal/sq. m * 1197.50 rubles / Gcal = 43.8285 rubles / sq.m.

May 0.0122 Gcal/sq. m * 1197.50 rubles / Gcal = 14.6095 rubles / sq.m

October 0.0322 * 1211.33 rubles / Gcal = 39.0048 rubles / sq.m.

November-December 0.0366 Gcal/sq. m * 1211.33 rubles / Gcal = 44.3347 rubles / sq.m

Calculation of the cost of services for hot water supply for 1 person in 2017:

January-June 0.2120 Gcal/per person per month * 1197.50 rubles / Gcal = 253.87 rubles / person

July-December 0.2120 Gcal/per 1 person per month * 1211.33 rubles / Gcal = 256.80 rubles / person

Calculation of the cost of services for hot water supply according to DHW meter in 2017:

January - June 0.0467 Gcal/cub. m * 1197.50 rubles / Gcal = 55.9233 rubles / cu. m.

July-December 0.0467 Gcal/cub. m * 1211.33 rubles / Gcal = 56.5691 rubles / cu. m

2016

Calculation of the cost of thermal energy for heating 1 sq. meters of total area in 2016:

January-April 0.0366 Gcal/sq. m * 1170.57 rubles / Gcal = 42.8429 rubles / sq.m.

May 0.0122 Gcal/sq. m * 1170.57 rubles / Gcal = 14.2810 rubles / sq.m

October 0.0322 * 1197.50 rubles / Gcal = 38.5595 rubles / sq.m.

November-December 0.0366 Gcal/sq. m * 1197.50 rubles / Gcal = 43.8285 rubles / sq.m

Calculation of the cost of services for hot water supply for 1 person in 2016:

January-June 0.2120 Gcal/per person per month * 1170.57 rubles / Gcal = 248.16 rubles / person

July-December 0.2120 Gcal/per 1 person per month * 1197.50 rubles / Gcal = 253.87 rubles / person

Calculation of the cost of services for hot water supply according to the DHW meter in 2016:

January - June 0.0467 Gcal/cub. m * 1170.57 rubles / Gcal = 54.6656 rubles / cubic meter m

July-December 0.0467 Gcal/cub. m * 1197.50 rubles / Gcal = 55.9233 rubles / cu. m

2015

Calculation of the cost of thermal energy for heating 1 sq. meters of total area in 2015:

Heating consumption standard * Tariff for thermal energy = cost of thermal energy for heating 1 sq. m:

January-April 0.0366 Gcal/sq. m * 990.50 rubles / Gcal = 36.2523 rubles / sq.m

May 0.0122 Gcal/sq. m * 990.50 rubles / Gcal = 12.0841 rubles / sq.m

October 0.0322 * 1170.57 rubles / Gcal = 37.6924 rubles / sq.m.

November-December 0.0366 Gcal/sq. m * 1170.57 rubles / Gcal = 42.8429 rubles / sq.m

Calculation of the cost of services for hot water supply for 1 person in 2015:

standard DHW consumption* Tariff for thermal energy = cost of DHW service per 1 person

An example of calculating the cost of a hot water service for 1 person with a complete improvement of the apartment (floors from 1 to 10, equipped with a sink, washbasin, bathroom 1500-1700 mm long with a shower) in the absence of hot water meters:

January-June 0.2120 Gcal/per person per month * 990.50 rubles / Gcal = 209.986 rubles / person

July-December 0.2120 Gcal/per 1 person per month * 1170.57 rubles / Gcal = 248.1608 rubles / person

Calculation of the cost of services for hot water supply according to the DHW meter in 2015:

Normative consumption of thermal energy for heating 1 cu. m of water * Tariff for thermal energy = cost of service for heating 1 cu. m

January - June 0.0467 Gcal/cub. m * 990.50 rubles / Gcal = 46.2564 rubles / cu. m

July-December 0.0467 Gcal/cub. m * 1170.57 rubles / Gcal = 54.6656 rubles / cubic meter m

year 2014

Calculation of the cost of thermal energy for heating 1 sq. meters of total area in 2014:

Heating consumption standard * Tariff for thermal energy = cost of thermal energy for heating 1 sq. m:

January-April 0.0366 Gcal/sq. m * 934.43 rubles / Gcal = 34.2001 rubles / sq.m

May 0.0122 Gcal/sq. m * 934.43 rubles / Gcal = 11.4000 rubles / sq.m

October 0.0322 Gcal/sq. m * 990.50 rubles / Gcal = 31.8941 rubles / sq. m

November - December 0.0366 Gcal/sq. m * 990.50 rubles / Gcal = 36.2523 rubles / sq.m

Calculation of the cost of services for hot water supply for 1 person in 2014:

DHW consumption standard * Tariff for thermal energy = cost of DHW service per 1 person

An example of calculating the cost of a hot water service for 1 person with a complete improvement of the apartment (floors from 1 to 10, equipped with a sink, washbasin, bathroom 1500-1700 mm long with a shower) in the absence of hot water meters:

January-June 0.2120 Gcal/per person per month * 934.43 rubles / Gcal = 198.0991 rubles / person

July - December 0.2120 Gcal / per 1 person. per month * 990.50 rubles / Gcal = 209.986 rubles / person

Calculation of the cost of services for hot water supply according to the DHW meter in 2014:

Normative consumption of thermal energy for heating 1 cu. m of water * Tariff for thermal energy = cost of service for heating 1 cu. m

January - June 0.0467 Gcal/cub. m * 934.43 rubles / Gcal = 43.6378 rubles / cubic meter m

July - December 0.0467 Gcal/cub. m * 990.50 rubles / Gcal = 46.2564 rubles / cu. m

year 2013

Calculation of the cost of thermal energy for heating 1 sq. meters of total area in 2013:

Heating consumption standard

• January-April 0.0366 Gcal/sq. m * 851.03 rubles / Gcal = 31.1477 rubles / sq.m
• May 0.0122 Gcal/sq. m * 851.03 rubles / Gcal = 10.3826 rubles / sq.m
• October 0.0322 Gcal/sq. m * 934.43 rubles / Gcal = 30.0886 rubles / sq. m
• November - December 0.0366 Gcal/sq. m * 934.43 rubles / Gcal = 34.2001 rubles / sq.m

Calculation of the cost of services for hot water supply for 1 person in 2013:

DHW consumption standard

An example of calculating the cost of a hot water service for 1 person with a complete improvement of the apartment (floors from 1 to 10, equipped with a sink, washbasin, bathroom 1500-1700 mm long with a shower) in the absence of hot water meters:

• January-June 0.2120 Gcal/per person per month * 851.03 rubles / Gcal = 180.4184 rubles / person
• July - December 0.2120 Gcal / per 1 person. per month * 934.43 rubles / Gcal = 198.0991 rubles / person

Calculation of the cost of services for hot water supply according to the DHW meter in 2013:

Normative consumption of thermal energy for heating 1 cu. m of water

• January - June 0.0467 Gcal/cub. m * 851.03 rubles / Gcal = 39.7431 rubles / cubic meter m
• July - December 0.0467 Gcal/cub. m * 934.43 rubles / Gcal = 43.6378 rubles / cubic meter m

year 2012

Calculation of the cost of thermal energy for heating 1 sq. meters of total area in 2012:

Heating consumption standard * Tariff for thermal energy (supplied by MUP ChKTS or OOO Mechel-Energo) = Cost of thermal energy for heating 1 sq. m

• January-April 0.0366 Gcal/sq. m * 747.48 rubles / Gcal = 27.3578 rubles / sq. m
• May 0.0122 Gcal/sq. m * 747.48 rubles / Gcal = 9.1193 rubles / sq. m
• October 0.0322 Gcal/sq. m * 851.03 rubles / Gcal = 27.4032 rubles / sq. m
• November - December 0.0366 Gcal/sq. m * 851.03 rubles / Gcal = 31.1477 rubles / sq. m

Calculation of the cost of hot water services per person in 2012:

DHW consumption standard * Tariff for thermal energy (supplied by MUP ChKTS or Mechel-Energo LLC) = cost of DHW service per person

An example of calculating the cost of a hot water service for 1 person with a complete improvement of the apartment (floors from 1 to 10, equipped with a sink, washbasin, bathroom 1500-1700 mm long with a shower) in the absence of hot water meters:

• January - June 0.2120 Gcal/per 1 person per month * 747.48 rubles / Gcal = 158.47 rubles / person
• July - August 0.2120 Gcal/per 1 person per month * 792.47 rubles / Gcal = 168.00 rubles / person
• September - December 0.2120 Gcal/per 1 person per month * 851.03 rubles / Gcal = 180.42 rubles / person

Calculation of the cost of hot water services according to the DHW meter in 2012:

Normative consumption of thermal energy for heating 1 cu. m of water * Tariff for thermal energy (supplied by MUP "CHKTS" or LLC "Mechel-Energo") = cost of service for heating 1 cubic meter. m

• January - June 0.0467 Gcal/cub. m * 747.48 rubles / Gcal = 34.9073 rubles / cu. m
• July - August 0.0467 Gcal / cub. m * 792.47 rubles / Gcal = 37.0083 rubles / cubic meter m
• September – December 0.0467 Gcal/cub. m * 851.03 rubles / Gcal = 39.7431 rubles / cubic meter m

Introduction:

The topic of calculating utility bills is one of the most difficult. For those who have not encountered the problem before, it is difficult to figure it out right away, and there seems to be no time for this.

However, let's try.

For calculations, RF GD No. 354 (procedure and methods for all occasions), RF GD No. 307 (only for heating and only until July 1, 2016, then RF GD No. 354 is valid), RF GD No. 306 (standards).

The text of the documents is complex, practically inaccessible to the mass payer. There is no clear notation physical quantities, which can confuse the reader, there are no names of physical quantities used in the calculation formulas and explanations. As if they were writing for themselves. Type we know ourselves, but the rest of us do not need to know.

And one more initial remark. Gentlemen from the Criminal Code and from the Developer often show great joy regarding the "energy efficiency" of new buildings, in particular in our area.

The essence of energy efficiency is a strict accounting of all communal resources and measures to save them. Let's see in the course of the discussion how justified such "joy".

Because we have a system DHW closed, that is, non-centralized, then the corresponding section of the RF GD No. 354 (Appendix 2, Section IV) is applied for calculations, when the production public service, in this case, hot water supply, is carried out by the contractor (MC) on our ITP equipment with you from the composition common property.

Regarding this very concept of "production" of hot water supply by the contractor, we will not go into details for now. This is a separate rather "muddy" and controversial topic, who actually produces what and how.

We only note that according to the RF GD No. 354, clause 54 of the Rules, it is clearly defined that the payment for the maintenance of common property ( ITP equipment where the service provider heats water for domestic hot water) is charged separately. That is, "production" - operating costs for this common property are included in the payment for the maintenance and repair of common property and are not included in the calculation of payment for hot water supply.

So, what should be taken into account when calculating the DHW fee?

Total consumption of cold drinking water(via the cold water line) supplied for heating for hot water supply.

The total consumption of thermal energy taken in boilers from the heat carrier from the centralized supply of thermal energy (heating).

Everything seemed simple. I divided the total heat consumption (heating) by the total volume of cold water that was used for hot water supply and the order. Got specific consumption heat per cubic meter of hot water.

However, in our receipts there is no accounting for the total volume of cold water and hot water separately.

And the data individual consumption for hot water and cold water cannot be used due to the systematic measurement error apartment meters. Therefore, the concept of ODN was introduced to eliminate this systematic error and to accurately calculate the total water consumption for the entire house by a common house meter.

In this sense, RF PP No. 354 is not quite correct and the campaign has long been outdated in some places, when it is proposed to use the total readings of the IPU as the basis for the calculations, if there is no common house meter, but at the same time, the authors of the regulatory text completely forgot about the systematic error of the apartment IPU (dead zone IPU at low water flow rates).

According to the law "On Energy Saving ...", the first thing to be done is to install common house metering devices, and where there is no technical possibility due to the design of the house, the technical possibility must be created by reconstructing (attaching) the premises for the installation of utility metering units.

The general house accounting of communal resources is not beneficial for public utilities, and therefore the process is sabotaged. AT " muddy water» cheating is easier.

Also, we don’t have a separate accounting for the consumption of thermal energy in the ITP, which is spent on heating hot water. At least this is not evident from the content of the information given in the receipt.

But what about the super duper energy efficient ITP? Isn't that too easy for a super duper energy efficient "space tech" ITP?

Have you installed one common cold water meter and one common heat energy meter for the entire unit and are happy like elephants?

And according to the Law, each individual house must be equipped with metering devices.

How does it differ then our ITP from the usual heating unit of the old Soviet house?

Why do we get "over the ears" every year about energy efficiency?

I'm looking for some crook - a "money pump" under an energy service contract "authoritatively" to say that we need to install metering devices to improve energy efficiency.

It is already clear to us that a comprehensive accounting of communal resources is needed.

Who prevented the installation of a two-channel heat energy meter? Was it difficult to plug in a meter to account for the consumption of make-up water for the DHW system?

And if they do exist, then why are their readings not used in calculations and not indicated in receipts?

Water consumption for the needs of hot water supply should be determined according to the norms of hot water consumption, taking into account the likelihood of using water taps. Determine the load on DHW system according to the maximum consumption of hot water and take it into account when choosing a heat source. Hello dear friends! We are accustomed to use every day hot water and we can hardly imagine comfortable life if you can not take a warm bath or you have to wash dishes under a tap from which a cold trickle pours. Water at desired temperature and the right amount- this is what the owner of each private house dreams of. Today we will determine the estimated consumption of water and heat for the hot water supply of our house. You must understand that at this stage it is not particularly important for us where we get this heat. Perhaps we will take it into account when choosing the power of the heat supply source and will heat water for the needs of hot water supply in the boiler. Perhaps we will heat the water in a separate electric boiler or a gas column, and perhaps it will be brought to us.

Well, what if there are no technical capabilities to carry out the hot water system at home, then we will go to our own or village bath. Our parents mostly went to the city baths, and now a mobile Russian bath has called under your window. Of course, life does not stand still and the presence of a bathtub and a shower cabin in the house today is no longer a luxury, but a simple necessity. Therefore, we will provide a hot water system in the house. The amount of load on the hot water supply system at home and, ultimately, the choice of heat source power will depend on the correct calculation of hot water supply. So come to this calculation need to be very serious. Before choosing the scheme and equipment of the DHW system at home, we need to calculate the main parameter of any system - the maximum hot water consumption per hour of maximum water consumption (Q g.v max, kg / h).

Practically, with the help of a stopwatch and a measuring container, we determine the flow of hot water, l / min when filling the bath

Calculation of the hourly maximum consumption of hot water per hour of its maximum water consumption

To calculate this consumption, let's turn to the hot water consumption rates (according to chapter SNiP 2-34-76), see table 1.

Hot water consumption rates (according to the chapter SNiP 2-34-76)

Table 1

g and.s - average for heating period, l/day;

g and - the highest water consumption, l / day;

g i.h - the highest water consumption, l / h.

Dear friends, I want to warn you against one common mistake. Many developers, and even young inexperienced designers, calculate the hourly maximum flow hot water formula

G max =g and.h *U, kg/h

g i.h - hot water consumption rate, l / h, the highest water consumption, is taken according to table 1; U - the number of consumers of hot water, U = 4 people.

G max = 10 * 4 = 40 kg/h or 0.67 l/min

Q g.v max \u003d 40 * 1 * (55 - 5) \u003d 2000 kcal/h or 2.326 kW

Having calculated the water flow in this way and choosing the power of the heat source to heat this flow, you calmed down. But getting under the shower, you will be surprised to find that only 3 drops of water per second drip on your dirty and sweaty bald head. Neither washing your hands, nor rinsing the dishes, not to mention taking a bath, is out of the question. So what's the deal? And the mistake is that the maximum hourly water consumption for the day of the highest water consumption is not correctly determined. It turns out that all hot water consumption rates according to Table 1 should only be used to calculate the flow rate through individual devices and the probability of using their action. These norms are not applicable for determining costs based on the number of consumers, by multiplying the number of consumers by the specific consumption! This is precisely the main mistake made by many calculators when determining the heat load on the DHW system.

If we need to determine the performance of heat generators (boilers) or heaters in the absence of hot water storage tanks for subscribers (our case), then the estimated load on the DHW system must be determined by the maximum hourly consumption of hot water (heat) per day of the highest water consumption according to the formula

Q g.v max =G max * c * (t g.sr -t x), kcal/h

G max - the maximum hourly consumption of hot water, kg / h. The maximum hourly consumption of hot water, G max, taking into account the likelihood of using water folding devices, should be determined by the formula

G max = 18 *g * K and * α h * 10 3, kg / h

g - hot water consumption rate, l / with water folding devices. In our case: for a washbasin g y \u003d 0.07 l / s; for washing g m = 0.14 l / s; for a shower g d \u003d 0.1 l / s; for a bath g in \u003d 0.2 l / s. Choose greater value, that is, g \u003d g in \u003d 0.2 l / s; K and - dimensionless coefficient of use of a water-folding device for 1 hour of the highest water consumption. For a bathtub with a characteristic (highest) flow rate of hot water g x \u003d 200 l / h, given coefficient will be equal to K and = 0.28; α h is a dimensionless value determined depending on the total number N of water-folding devices and the probability of using them Р h for 1 hour of the highest water consumption. In turn, the probability of using water folding devices can be determined by the formula

R h =g and.h *U / 3600 * K and *g*N

g i.h - hot water consumption rate per hour of the highest water consumption, l / h. It is taken according to table 1, g i.h = 10l / h; N is the total number of taps installed in the house, N = 4.

R h \u003d 10 * 4 / 3600 * 0.28 * 0.2 * 4 \u003d 0.0496. At R h< 0,1 и любом N по таблице (N * Р ч = 0,198) определяем α ч = 0,44

G max \u003d 18 * 0.2 * 0.28 * 0.44 * 10 3 \u003d 444 kg / h or 7.4 l / min.

Q g.v max \u003d 444 * 1 * (55 - 5) \u003d 22200 kcal / h or 25.8 kW

No, neither the desired temperature, nor the proper flow of hot water - discomfort

As you can see, dear friends, the consumption of water and, accordingly, heat has increased by about 10 times. In addition, the heat consumption for hot water supply (25.8 kW) is 2 times more than the total heat consumption for heating and ventilation of the house (11.85 + 1.46 = 13.31 kW). If this data is presented to the "Customer", then his hair will stand on end and he will demand that they explain to him - what's the matter? So let's help him. Tables 2 and 3 below will help us with this. Now let's turn to table 2 and calculate the hourly highest flow water when loading all water consumers at the same time. Adding all the typical flow rates, we get 530 l/h. As you can see, the total typical flow rate turned out to be more than the calculated one (444l/h) by 86 l/h. And this is not surprising, since the likelihood that all water folding devices will work at the same time is very small. We have and so the value of meeting the demand for hot water from the maximum is 84%. In reality, this value is even less - about 50%. Let's try to get a real value, for this we use table 3. Do not forget that hot water consumption rates are developed for consumers at t g.av = 55 ° C, but we will find costs from the table at t g.av = 40 ° C.

The minimum total consumption of hot water, with an average water temperature equal to tg.w = 40 ° C and the simultaneous operation of all water intake devices with a security of this flow rate of 84%, will be equal to G min \u003d [ (5 * 1.5) + (20 * 5) + (30 * 6) + (120 * 10)] * 0.84 \u003d 342.3 l / h (239.6 l / h at t g.v \u003d 55 ° C)

The maximum total consumption of hot water, with an average water temperature equal to 40 ° C and the simultaneous operation of all water intake devices with a security of this flow rate of 84%, will be equal to G max \u003d [ (15 * 3) + (30 * 5) + (90 * 6 ) + (200 * 15)] * 0.84 \u003d 869.4 l / h (608.6 l / h at t g.v \u003d 55 ° C)

The average consumption at t g.w. = 55 ° C will be equal to G medium = (G min + G max) / 2 = (239.6 + 608.6) / 2 = 424.1 l / h. So we got what we were looking for - 424.1 l / h instead of 444 l / h according to the calculation.

Hot water consumption rates for water-folding devices (chapter SNiP 2-34-76)

table 2

Hot water consumption rates for various water intake devices

Table 3

Thus, when calculating hot water supply in without fail it is necessary to take into account such nuances: the number of residents; frequency of using the bathroom, shower; the number of bathrooms where hot water is used; specifications plumbing elements (for example, the volume of the bathroom); the expected temperature of the heated water, as well as the likelihood of using water taps at the same time. In the following posts, we will take a closer look at three common hot water systems. Depending on the method of heating water, these systems, for private country house, subdivided: DHW with storage water heater(boiler); DHW with instantaneous water heater; DHW with a double-circuit boiler.

What do you think I'm doing?!!!

The obtained values ​​of water and heat consumption for the needs of hot water supply - G max \u003d 444 kg / h or 7.4 l / min and Q g.v max \u003d 22200 kcal / h or 25.8 kW we accept, with subsequent clarification, when choosing a heat source. Today we have completed the 4th point of our plan for the house - we have calculated the hourly maximum consumption of hot water for a private house. If you haven't joined yet, please join!

Sincerely, Gregory

The calculation of hot water supply systems consists in determining the diameters of the supply and circulation pipelines, selecting water heaters (heat exchangers), generators and heat accumulators (if necessary), determining the required pressure at the inlet, selecting booster and circulation pumps if they are needed.

The calculation of the hot water supply system consists of the following sections:

The estimated costs of water and heat are determined and, on the basis of this, the power and dimensions of the water heaters.

The supply (distribution) network is calculated in the drawdown mode.

The hot water supply network is calculated in circulation mode; the possibilities of using natural circulation, and if necessary, parameters are determined and circulation pumps are selected.

In accordance with the individual task for the course and diploma design, the calculation of storage tanks, the coolant network can be made.

2.2.1. Determination of the estimated costs of hot water and heat. Selection of water heaters

To determine the heating surface and further selection of water heaters, hourly flow rates of hot water and heat are required, for calculating pipelines - second flow rates of hot water.

In accordance with clause 3 of SNiP 2.04.01-85, the second and hourly consumption of hot water is determined by the same formulas as for cold water supply.

The maximum second flow of hot water in any calculated section of the network is determined by the formula:

- second consumption of hot water by one device, which is determined by:

a separate device - according to mandatory Appendix 2;

various devices serving the same consumers - according to Appendix 3;

various devices serving various water consumers - according to the formula:

, (2.2)

- second consumption of hot water, l / s, by one water-folding device for each consumer group: taken according to Appendix 3;

N i is the number of water folding devices for each type of water consumer;

- the probability of operation of devices, determined for each group of water consumers;

a - coefficient determined according to Appendix 4, depending on the total number of devices N in the network section and the probability of their action P, which is determined by the formulas:

a) with the same water consumers in buildings or structures

, (2.3)

where
- the maximum hourly consumption of hot water in 1 liter by one water consumer, is taken according to Appendix 3;

U - the number of hot water consumers in a building or structure;

N is the number of devices served by the hot water supply system;

b) with different groups of water consumers in buildings for various purposes

, (2.4)

and N i - values ​​related to each group of hot water consumers.

The maximum hourly consumption of hot water, m 3 / h, is determined by the formula:

, (2.5)

- hourly consumption of hot water by one device, which is determined by:

a) with identical consumers - according to Appendix 3;

b) for different consumers - according to the formula

, l/s (2.6)

and
- values ​​related to each type of hot water consumer;

magnitude is determined by the formula:

, (2.7)

- coefficient determined according to Appendix 4, depending on the total number of devices N in the hot water supply system and the probability of their action P.

Average hourly hot water consumption , m 3 / h, for the period (day, shift) of maximum water consumption, including, is determined by the formula:

, (2.8)

- the maximum daily consumption of hot water in 1 liter by one water consumer, is taken according to Appendix 3;

U is the number of hot water consumers.

The amount of heat (heat flow) for the period (day, shift) of maximum water consumption for the needs of hot water supply, taking into account heat losses, is determined by the formulas:

a) within the maximum hour

b) during the average hour

and - maximum and average hourly consumption of hot water in m 3 / h, determined by formulas (2.5) and (2.8);

t s is the design temperature of cold water; in the absence of data in the building, t is assumed to be + 5ºС;

Q ht - heat loss by the supply and circulation pipelines, kW, which are determined by calculation depending on the lengths of the pipeline sections, the outer diameters of the pipes, the temperature difference between hot water and the environment surrounding the pipeline and the heat transfer coefficient through the pipe walls; while taking into account the efficiency of pipe insulation. Depending on these values, heat losses are given in various reference manuals.

When calculating in course projects, heat loss Q ht by supply and circulation pipes can be taken in the amount of 0.2-0.3 of the amount of heat required to prepare hot water.

In this case, formulas (2.9) and (2.10) will take the form:

a), kW (2.11)

b) , kW (2.12)

A smaller percentage of heat loss is accepted for systems without circulation. In most civil buildings, fast sectional water heaters with variable performance are used, i.e. with adjustable heat carrier consumer. Such water heaters do not require heat storage tanks and are calculated for the maximum hourly heat flow.
.

The selection of water heaters consists in determining the heating surface of the coils according to the formula:

, m 3 (2.13)

K - heat transfer coefficient of the water heater, taken according to table 11.2; for high-speed water-to-water heaters with brass heating tubes, the value of k can be taken in the range of 1200-3000 W / m2, ºС, and the smaller one is accepted for devices with smaller section diameters;

µ - coefficient of reduction of heat transfer through the heat exchange surface due to deposits on the walls (µ=0.7);

- estimated temperature difference between the coolant and heated water; for counterflow instantaneous water heaters
º is determined by the formula:

, ºС (2.14)

Δt b and Δt m - greater and lesser temperature difference between the coolant and the heated water at the ends of the water heater.

Coolant parameters in the winter settlement period, when they work heating networks buildings, are taken in the supply pipeline 110-130 ºС and in the reverse -70, the parameters of the heated water during this period t c = 5 ºC and t c = 60 ... 70 ºC. AT summer period the heating system works only for the preparation of hot water; the parameters of the heat carrier during this period in the supply pipeline 70…80 ºC and in the return 30…40 ºC, the parameters of the heated water and t c = 10…20 ºC and and t c = 60…70 ºC.

When calculating the heating surface of a water heater, it may happen that the summer period will be decisive, when the temperature of the heat carrier is lower.

For storage water heaters, the calculation for the temperature difference is determined by the formula:

, ºC (2.15)

t n and t k - initial and final temperature of the coolant;

t h and t c - temperature of hot and cold water.

However, storage water heaters are used for industrial buildings. They take up a lot of space, in these cases they can be installed outdoors.

The heat transfer coefficient for such water heaters, according to table 11.2, is 348 W / m 2 ºC.

The required number of standard sections of water heaters is determined:

, pcs (2.16)

F is the calculated heating surface of the water heater, m 2;

f - heating surface of one section of the water heater, taken according to Appendix 8.

The pressure loss in an instantaneous water heater can be determined by the formula:

, m (2.17)

n - coefficient taking into account the overgrowth of tubes, is taken according to experimental data: in their absence, with one cleaning of the water heater per year, n = 4;

m is the coefficient of hydraulic resistance of one section of the water heater: with a section length of 4 m m=0.75, with a section length of 2 m m=0.4;

n in - the number of sections of the water heater;

v - speed of movement of heated water in the tubes of the water heater without taking into account their overgrowth.

, m/s (2.18)

q h - maximum second water flow through the water heater, m/s;

W total - total area the living section of the water heater tubes is determined by the number of tubes, taken according to Appendix 8, and the diameter of the tubes, taken 14 mm.