Every homeowner must know how to calculate hot water for subsequent payment. The fact is that the provision of this service occurs in quantitative terms, and if the consumption hot water calculate incorrectly, it can result in quite a large sum overpayment or debt.

In addition, if, as a result of such an error, you do not pay for the hot water supplied to you on time, this may lead to its shutdown.

If you do not pay for the hot water supplied to you on time, this may lead to its shutdown

Payment for services for the supply of hot water to the population is regulated by Decree of the Government of the Russian Federation dated May 6, 2011 No. 354. According to it, it must include 2 components:

1. Providing hot water supply directly to residential or non-residential premises.
2. Provision of hot water supply for general house needs or for land plot, as well as the auxiliary buildings located on it.

Usually centralized systems hot water supply is used in cities to supply such water to apartments, communal apartments and rooms in apartment buildings. Tariffs for hot water are set by the Federal Tariff Service, as well as its divisions in the regions, so if you don’t know how to calculate the tariff for hot water, you can go to the website of this body. In addition, your local resource supply organization can provide you with an example of such a calculation.

Tariffs for hot water are set by the Federal Tariff Service

In any case, it is worth knowing that the formula for calculating the cost of hot water includes not only the tariff itself, but also other indicators. For example, if your utility organization has established a two-rate tariff, then you will pay:

• payment for the consumption of one cubic meter of hot water;
• payment for the maintenance of the hot water supply system based on one gigocalorie.

With a one-component tariff, only consumed cubic meters are paid, which includes expenses for other needs. In addition, the approved methodology, which answers the question of how to calculate and how much a cube of hot water costs, also takes into account what category of consumers you belong to. This could be industry, public institutions or the population.

A common house hot water meter is used, which is installed on the basis of a decision of the general meeting of owners of residential premises

If other categories of consumers have all questions about utility bills are decided by special employees on the staff of a legal entity, then the population calculates and pays for the consumption of hot water independently. At the same time, he is also entrusted with the obligation to pay expenses for general household needs. For this purpose, a common house hot water meter is used, which is installed on the basis of a decision of the general meeting of owners of residential premises.

A separate scheme is used to calculate hot water supply if an individual boiler room is installed in the house. So, in the bills there is no line “hot water supply”, and instead there are 2 positions: water heating and cold water supply for hot water supply. This subtlety will need to be taken into account by all homeowners in such houses.

Payment for hot water for the population

• according to the counter;
• according to the general standard.

The first option is the most profitable for the owner of a residential premises, since it allows him to pay only for the volume of hot water that he actually consumed. At the same time, every month he will need to transfer meter readings to the local resource supply company. It is usually called “Vodokanal” or “Teploenergo” and is municipally owned.

Payment for hot water by meter

In the second case, you have to pay based on the general standard established by the Government, taking into account the number of residents registered in a particular living space. Typically, the standard is applied when the apartment does not have a meter installed or it is broken. At the same time, as a measure to encourage the population to install metering devices, the Government has been gradually increasing the standards by 1.6 times by 2017 since 2015.

As for specific figures, for 2016 in Moscow the standard for hot water consumption is 166 liters per day per person. It may be different in other regions. In any case, it will be more profitable to pay using a meter, so it makes sense to install it in the premises as early as possible.

Important! In addition to the standard and meter readings, the cost of hot water is also calculated taking into account the readings of a common house meter.

You can find out how to calculate one for hot water by contacting a company that provides services for managing your apartment building. Generally speaking, apartment meter readings are subtracted from the readings of the general building meter, and the resulting balance is divided, based on a special formula, among all residents registered in the house.

Hot water payment receipts

Directly residents apartment buildings Usually they don’t do calculations alone. Since this is the responsibility of the local housing department or homeowners association, for them there is a special line in the payment receipt with this indicator, which will need to be paid as part of the general receipt. If the amount in your opinion is too high, this may be the reason for your request to recalculate it. This should do Management Company within ten days. If this does not happen, you have the right to appeal the company’s actions to the Housing Inspectorate or court.

It is also worth keeping in mind that modern technologies allow you to make payments utilities remotely or on a special schedule. This will be especially convenient if you leave your region of residence for some time or are very busy. To make payments according to the schedule, you will need to write a statement to your local bank branch about this or set it up accordingly Personal Area on your bank's website.

In any case, try to pay the cost of hot water in full and on time

Next, the required payment amounts will be withdrawn from your account at the right time, which will allow you to avoid becoming a debtor on utility bills. In any case, try to pay the cost of hot water in full and on time.

Transmission of meter readings

As you already understood, the easiest way to calculate hot water consumption is to take readings from a meter installed in a residential area. This procedure must be carried out once a month. To do this, you will need to write off the first 5 digits of the readings from the meter.

Calculation of hot water consumption

Based on them, you can independently calculate your hot water consumption. To do this, subtract the new readings from last month’s readings. The difference you receive will be your monthly expense.

If you are wondering how to calculate hot water from a receipt, then you can do this by multiplying the readings obtained using a meter by the tariff in force in your region. This calculation may be useful to you when you have questions about the numbers indicated in payment receipt. With complaints about this, you often contact the resource supply company, where you are required to recalculate the hot water you consumed.

Unscheduled water meter check

After you take the hot water meter readings, they will need to be transferred to the water supply organization. This can be done in several ways, for example:

• using the website of such an organization or management company;
• using special forms;
• at the office of the organization that supplies you with burning water.

After transmitting the readings individual device To meter hot water, you will only have to wait until you receive a receipt for payment. If you have figured out how to calculate hot water before this time, you can double-check the amount billed to you to avoid mistakes. At the same time, if several water meters are installed in your apartment, you will have to transmit readings from all of them.

By the way, you will need not only knowledge of how to calculate hot water, but also how to check the accuracy of the meter reading. To do this, record the readings of the three red numbers on its scale, after which approximately 30 liters of water are drained from the tap using a ten-liter bucket. If the meter shows a higher or lower number, this may be a sign that the water meter requires an unscheduled check.

Internet banking for paying for hot water

After an invoice is issued to you based on the testimony you provided, you can pay it in several ways, for example, at Russian Post, through Internet banking, and also using an ATM. If you delay payment for more than 3 months, you may be charged a penalty and your hot water may be turned off. After six months, utility companies will be able to go to court to evict you from the premises you occupy.

Water consumption for hot water supply needs should be determined according to hot water consumption standards, taking into account the likelihood of using water taps. Determine the load on DHW system according to the maximum flow rate of hot water and take it into account when choosing a heat source. Hello, dear friends! We are used to using it every day hot water and we can hardly imagine comfortable life, if you cannot take a warm bath or you have to wash dishes under a tap from which a cold stream flows. Water desired temperature and in the right quantity - this is what the owner of every private home dreams of. Today we will determine the estimated water and heat consumption for hot water supply to our home. You must understand that at this stage it is not particularly important to 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 water in a separate electric boiler or a gas water heater, or perhaps they will bring it to us.

Well, what if there are no technical capabilities If we install a domestic hot water system at home, then we will go to our own or the village bathhouse. Our parents mostly went to the city baths, and now the mobile Russian bathhouse under your window has rung. Of course, life does not stand still and having a bath and shower in the house today is no longer a luxury, but a simple necessity. Therefore, we will provide a hot water supply system in the house. The correct calculation of the hot water supply will determine the load on the domestic hot water system and, ultimately, the choice of the power of the heat source. Therefore, this calculation must be approached very seriously. Before choosing the design and equipment of a domestic hot water system, we need to calculate the main parameter of any system - the maximum hot water flow per hour maximum water consumption(Q g.v max, kg/h).

In practice, using a stopwatch and a measuring container, we determine the consumption of hot water, l/min when filling the bathtub

Calculation of the hourly maximum hot water flow rate per hour of maximum water consumption

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

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

Table 1

g и.с – average for heating season, l/day;

g and – maximum water consumption, l/day;

g i.h – 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 hot water flow using the formula

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

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

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

Q year max = 40 * 1 * (55 – 5) = 2000 kcal/h or 2.326 kW

Having calculated the water flow in this way and selected the power of the heat source to heat this flow, you have calmed down. But when you get into the shower, you will be surprised to discover that only 3 drops of water per second are dripping onto 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 greatest water consumption was not correctly determined. It turns out that all hot water consumption rates according to Table 1 should be used only to calculate the flow rate through individual devices and the likelihood of using their action. These standards are not applicable for determining costs based on the number of consumers, by multiplying the number of consumers by specific consumption! This is precisely the main mistake made by many calculators when determining the heat load on a hot water supply 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 hot water system must be determined by the maximum hourly consumption of hot water (heat) for the day of greatest water consumption using the formula

Q g.v max =G max * s * (t g.wed –t x), kcal/h

G max – 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 taps, 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 taps. In our case: for a washbasin g y = 0.07 l/s; for washing g m = 0.14 l/s; for shower g d = 0.1 l/s; for a bath g in = 0.2 l/s. We choose a larger value, that is, g = g in = 0.2 l/s; K and – dimensionless coefficient of use of a water-folding device for 1 hour of maximum water consumption. For a bathtub with a characteristic (highest) hot water flow g x = 200 l/h, this coefficient will be equal to K u = 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 R h for 1 hour of greatest water consumption. In turn, the probability of using water-folding devices can be determined by the formula

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

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

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

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

Q year max = 444 * 1 * (55 – 5) = 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 approximately 10 times. In addition, the heat consumption for hot water supply (25.8 kW) is 2 times greater 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 highest hourly water consumption when loading all water consumers at the same time. Adding up all the typical costs, we get 530 l/h. As you can see, the total characteristic consumption turned out to be 86 l/h more than the calculated one (444 l/h). And this is not surprising, since the likelihood that all water taps will work at the same time is very small. Our maximum requirement for hot water is already 84%. In reality, this value is even less – about 50%. Let's try to get the real value, for this we use table 3. Do not forget that hot water consumption standards are developed for consumers at t g.av = 55 o C, but from the table we will find costs at t g. av = 40 o C.

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

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

The average flow rate at t g.v = 55 o C will be equal to G avg = (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 calculations.

Hot water consumption standards for water taps (chapter SNiP 2-34-76)

table 2

Hot water consumption standards for various water intake devices

Table 3

Collection point	Sink	Kitchen sink	Economical shower	Shower standard	Shower comfort.	Bath
DHW temperature, o C	35-40	55	40	40	40	40
Consumption time, min	1,5-3	5	6	6	6	10-15
Hot water consumption for domestic needs, l	5-15	20-30	30	50	90	120-200

Thus, when calculating hot water supply, it is imperative to take into account the following nuances: the number of residents; frequency of use of the bath, shower; number of bathrooms where hot water is used; technical characteristics of 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 next posts We will take a closer look at three common hot water supply 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 double-circuit boiler.

What do you think I’m doing?!!!

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

Best regards, Gregory

Introduction

1. Determination of the thermal loads of the microdistrict for heating, ventilation, hot water supply

2. Selecting a scheme for connecting the hot water heater to the heating network and temperature chart TsKR

Thermal hydraulic calculation of a shell-and-tube heater

Calculation of two-stage sequential circuit connection of DHW water heaters

Thermal and hydraulic calculation of plate hot water heaters

List of sources used

INTRODUCTION

In this work, the thermal loads of the microdistrict for heating and hot water supply are calculated, a scheme for switching on hot water heaters is selected, and thermal and hydraulic calculations of two heat exchanger options are performed. Only residential buildings of the same type, 5-10 storeys, will be considered. The coolant system is closed, 4-pipe with installation of a hot water heater in the central heating substation. All calculations are carried out using aggregated indicators. We accept residential buildings without ventilation.

Calculation and graphic work is carried out in accordance with the current standard norms and rules, technical. conditions and basic provisions for the design, installation and operation of heat supply systems for residential buildings.

1. Determination of the thermal loads of the microdistrict for heating, ventilation, and hot water supply.

Maximum heat flow for heating residential buildings in the microdistrict:

where is the aggregated indicator of the maximum heat flow for m²;

A - total area of ​​the residential building, m²;

The coefficient of heat flow for heating residential buildings (share of residential buildings)

80 W/m² Astrakhan

A= 16400 m² - as specified

0, because Only residential buildings are considered.

Maximum heat flow for hot water supply

where is the coefficient of hourly uneven consumption of the number of FGPs

The aggregated indicator of the average heat flow for hot water supply is 376 W/ml;

U - the number of residents in the microdistrict, according to the assignment, is equal to 560 people;

376 W/ml;

Thermal loads on ventilation for a residential building are zero.

2. Selecting a scheme for connecting the hot water heater to the heating network and the temperature schedule of the central heating system

Selecting a heater connection diagram

where - from formula (2)

From formula (1)

When accepted two-stage scheme, when a single-stage parallel circuit is adopted

Conclusion: there is only one heater, therefore one common heater located in the central heating center is connected in 2 ways step scheme.

According to the instructions of the TsKR, heat supply is carried out according to the domestic heating schedule of 130/700C, therefore the parameters of the break point, which are calculated, are known and amount to;

Maximum flow on - average heat flow for hot water supply (DHW)

where is the maximum heat flow to the hot water supply from formula (2)

Coefficient of hourly unevenness in FGP consumption

3. Thermal hydraulic calculation of a shell-and-tube heater

Outside air temperature at the "breaking point"

where is the indoor air temperature,

Design air temperature for heating design,

water temperature in the falling pipeline at the “break point”,

The water temperature is approximately in the return line at the "breaking point", at design temperature coolant in the falling pipeline 1300C.

Estimated water temperature difference in the heating network, determined by the formula

where is the design temperature network water in the supply pipeline,

Estimated temperature of network water in the return pipeline,

4. Calculation of a two-stage sequential connection scheme for DHW water heaters

heating ventilation shell and tube heater

Select and calculate a water heating installation for DHW central heating station equipped with a water heater consisting of shell-and-tube type sections with a pipe system of straight smooth pipes with a block of supporting partitions in accordance with GOST 27590. The heating system of the microdistrict is connected to the main heating network according to a dependent circuit. The central heating station has storage tanks.

Initial data:

The temperature of the coolant (heating water) in accordance with the calculated increased schedule is accepted:

At the calculated outside air temperature for heating design;

in the supply line ? 1 = 130 0С, in reverse - ? 2 = 700С;

at the break point of the temperature graph t` n= -2.02 0С;

in the supply line ? 1 n= 70 0С, reverse ? 2 n= 44.9 0C.

Cold temperature tap water tc=5 0 WITH.

The temperature of the hot water entering the SGV is th=60 0 WITH.

Maximum heat flow for heating buildings Qo max= 1312000 W.

Estimated thermal performance of water heaters Qsph=Qhm=QhT=210560 W .

6 Heat loss by pipelines Qht=0.

Take water density ?= 1000 kg/m3.

Maximum calculated second water consumption for hot water supply qh= 2.5 l/s.

Calculation procedure:

Maximum calculation of water for heating:

Temperature of heated water behind the 1st stage water heater:

Consumption of heating network water for DHW:

4 Consumption of heated water for DHW:

Heat flow to stage II of the SGV water heater:

Heat flow for heating at the break point of the network water temperature graph at outside air temperature t`n:

Heating water flow through the first stage of the water heater:

Estimated thermal performance of the first stage of the water heater:

Estimated thermal performance of the second stage of the water heater:

Temperature of heating network water at the outlet of the second stage water heater:

The temperature of the heating network water at the outlet of the first stage water heater, subject to equality:

12 Average logarithmic temperature difference between heating and heated water for stage 1:

The same for stage II:

The required cross-section of the water heater tubes at the water speed in the tubes and with single-flow operation:

From the table adj. 3, based on the obtained value, we select the type of water heater section with the following characteristics: , .

Water speed in tubes:

Speed ​​of network water in the annulus:

Calculation of the 1st stage of the DHW water heater:

e) heat transfer coefficient at:

e) required heating surface of stage 1:

g) number of sections of the 1st stage water heater:

We accept 2 sections; actual heating surface F1tr=0.65*2=1.3 m2.

Calculation of the second stage of the SGV water heater:

a) average temperature of heating water:

b) average temperature of heated water:

c) heat transfer coefficient from heating water to the walls of the tubes:

d) heat transfer coefficient from the walls of the tubes to the heated water:

e) heat transfer coefficient at

f) required heating surface of stage II:

g) number of sections of the second stage water heater:

We accept 6 sections.

As a result of the calculation, we obtained 2 sections in the 1st stage heater and 6 sections in the 2nd stage heater with a total heating surface of 5.55 m2.

Pressure loss in water heaters (6 consecutive sections 2 m long) for water passing in tubes taking into account? = 2:

Stage I: PV 76*2-1.0-RG-2-UZ GOST 27590-88

II stage: PV 76*2-1.0-RG-6-UZ GOST 27590-88

5. Thermal and hydraulic calculation of plate hot water heaters

Select and calculate the water heating installation of a plate heat exchanger assembled from 0.3p plates for the SGW of the same central heating station as in the example with shell-and-tube sectional heaters. Consequently, the initial data, flow rates and temperatures of coolants at the inlet and outlet of each stage of the water heater are taken to be the same as in the appendix. 3.

We check the ratio of strokes in the first stage heat exchanger, first taking the pressure loss for the heated water? Рн = 100 kPa, for the heating water? Рgr = 40 kPa.

The stroke ratio does not exceed 2, but the flow rate of heating water is much greater than the flow rate of heated water, therefore, an asymmetrical arrangement of the heat exchanger is adopted.

By optimal speed water and the open cross-section of one interplate channel, we determine the required number of channels for heated water and heating water:

General live section channels in the package along the flow of heated and heating water (taken equal to 2, =15):

Actual speeds of heating and heated water:

Calculation of the 1st stage water heater:

a) from Table 1, Appendix 4; we obtain the heat transfer coefficient from the heating water to the plate wall:

b) heat absorption coefficient from the plate wall to the heated water:

d) required heating surface of the 1st stage water heater:

e) according to Table 1, Appendix 4, heating surface of one plate, number of strokes through heating and heated water in the heat exchanger:

f) actual heating surface of the first stage water heater:

g) stage 1 pressure losses for heating and heated water:

Calculation of the second stage water heater:

a) heat transfer coefficient from the heating water to the plate wall:

b) heat absorption coefficient from the plate to the heated water:

c) , heat transfer coefficient:

d) required heating surface of the second stage water heater:

e) number of strokes through heating and heated water in the heat exchanger:

We accept by heating water, by heated water.

f) actual heating surface of the second stage water heater:

g) pressure loss of stage II for heating and heated water:

As a result of the calculation, we accept two heat exchangers (stages I and II) of a collapsible design (p) with plates of type 0.3p, 1 mm thick, made of steel 12×18N10T (version 01), on a cantilever frame (version 1k) as a DHW heater. With sealing gaskets made of rubber brand 51-1481 (symbol 12). The heating surface of stage I is 8.7 m2, stage II is 8.7 m2. Specifications plate heat exchangers are given in Table 1-3 app. 4.

Symbol heat exchangers:

Steps: P 0.3r-1-8.7-1k-0.1-12 CX1=

II Stage: P 0.3r-1-8.7-1k-0.1-12 CX2=

LIST OF SOURCES USED

1. SNiP 2.04.01-85. Internal water supply and sewerage of buildings.

Lipovka Yu.L., Tselishchev A.V., Misyutina I.V. Hot water supply: method. instructions for course work. Krasnoyarsk: SFU, 2011. 36 p.

GOST 27590-88. Water-to-water heaters for heating systems. Are common technical specifications.

SNiP 2.04.07-89*. Heating network.

5. SNiP 23-01-99. Construction climatology.

6. STO 4.2 - 07 - 2012 Quality management system. General requirements to the construction, presentation and execution of documents of educational activities. Instead of STO 4.2 - 07 - 2010; date entered 02/27/2012. Krasnoyarsk: IPK SFU. 2012. 57 p.

Tutoring

Need help studying a topic?

Our specialists will advise or provide tutoring services on topics that interest you.
Submit your application indicating the topic right now to find out about the possibility of obtaining a consultation.

Published: 05.12.2010 | |

Throughout 2004, our organization received applications for the development of technical proposals for boiler houses for heat supply to residential and public buildings, in which the loads on hot water supply were very different (to a lesser extent) from those previously requested for identical consumers. This was the reason for analyzing the methods for determining the loads on hot water supply (DHW), which are given in the current SNiPs, and possible errors arising when they are used in practice.
E.O. SIBIRKO

Currently, the procedure for determining heat loads on hot water supply is regulated normative document SNiP 2.04.01–85* “Internal water supply and sewerage of buildings.”

The methodology for determining the estimated flow rates of hot water (maximum second, maximum hourly and average hourly) and heat flows (heat power) per hour at average and maximum water consumption in accordance with section 3 of SNiP 2.04.01–85* is based on the calculation of the corresponding costs through water-folding devices (or groups of similar devices with subsequent averaging) and determining the probability of their simultaneous use.

All service tables with data on various specific consumption rates, etc., given in SNiP, are used only for calculating the flow rate through individual devices and the probability of their operation. They are not applicable for determining costs based on the number of consumers, by multiplying the number of consumers by specific consumption! This is precisely the main mistake made by many calculators when determining the heat load on the hot water supply.

The presentation of the calculation methodology in section 3 of SNiP 2.04.01–85* is not simple. Introduction of numerous superscript and subscript Latin indices (derived from the corresponding terms in English language) makes it even more difficult to understand the meaning of the calculation. It is not entirely clear why this was done in the Russian SNiP - after all, not everyone speaks English and easily associates the index “ h"(from English hot- hot), index " c"(from English cold- cold) and " tot"(from English total- result) with corresponding Russian concepts.

To illustrate the standard error encountered in calculations of heat and fuel needs, I will give a simple example. Need to determine DHW load for a 45-apartment residential building with a population of 114 people. The water temperature in the DHW supply pipeline is 55°C, temperature cold water V winter period-5°C. For clarity, let’s assume that each apartment has two similar water points (sink in the kitchen and washbasin in the bathroom).

Option I of calculation is incorrect (we have repeatedly encountered this method of calculation):

According to the table “Rates of water consumption by consumers” of the mandatory Appendix 3 of SNiP 2.04.01–85*, we determine for “Apartment-type residential buildings: with bathtubs from 1500 to 1700 mm long, equipped with showers” ​​the hot water consumption per inhabitant at the hour of greatest water consumption is equal to q hhr, u = 10 l/h. Then everything seems to be quite simple. The total consumption of hot water per house at the hour of greatest water consumption based on the number of inhabitants of 114 people: 10. 114 = 1140 l/h.

Then, the heat consumption per hour of greatest water consumption will be equal to:

Where U- number of residents in the house; g - density of water, 1 kg/l; With- heat capacity of water, 1 kcal/(kg °C); t h - hot water temperature, 55°C; t c - cold water temperature, 5°C.

The boiler room, actually built on the basis of this calculation, clearly could not cope with the load of hot water supply at the moments of peak hot water supply, as evidenced by numerous complaints from the residents of this house. Where is the mistake here? It lies in the fact that if you carefully read section 3 of SNiP 2.04.01–85*, it turns out that the indicator q hhr, u, given in Appendix 3, is used in the calculation method only to determine the probability of operation of sanitary fixtures, and the maximum hourly flow of hot water is determined completely differently.

Calculation option II - in strict accordance with the SNiP methodology:

1. Determine the probability of the device operating.

,

Where q hhr,u = 10 l - according to Appendix 3 for this type of water consumer; U= 114 people - the number of residents in the house; q h0 = 0.2 l/s - in accordance with clause 3.2 for residential and public buildings, it is allowed to take this value in the absence technical characteristics devices; N- the number of sanitary fixtures with hot water, based on the two water points we have adopted in each apartment:

N= 45. 2 = 90 devices.

Thus we get:

R= (10 x 114)/(0.2 x 90 x 3600) = 0.017.

2. Now let’s determine the probability of using sanitary appliances (the ability of the appliance to supply normalized hourly water flow) during the estimated hour:

,
Where P- the probability of the device action determined in the previous paragraph, - P= 0,017; q h0 = 0.2 l/s - second water flow rate related to one device (also already used in the previous paragraph); q h0,hr - hourly water consumption by the device, in accordance with clause 3.6, in the absence of technical characteristics of specific devices, it is allowed to take q h0,hr = 200 l/h, then:

.

3. Since P h is less than 0.1, we further use the table. 2 of Appendix 4, according to which we determine:

at .

4. Now we can determine the maximum hourly hot water flow:

.

5. And finally, we determine the maximum thermal load DHW (heat flow during the period of maximum water consumption during the hour of maximum consumption):

,

Where Q ht- heat losses.

Let's take into account heat losses, taking them as 5% of the design load.

.

We got a result more than twice the result of the first calculation! As practical experience shows, this result is much closer to the real needs for hot water for a 45-apartment residential building.

You can give for comparison the result of the calculation using the old method, which is given in most reference literature.

Option III. Calculation using the old method. Maximum hourly heat consumption for hot water supply needs for residential buildings, hotels and hospitals general type by the number of consumers (in accordance with SNiP IIG.8–62) was determined as follows:

,

Where k h - coefficient of hourly unevenness of hot water consumption, taken, for example, according to table. 1.14 reference book “Adjustment and operation of water heating networks” (see Table 1); n 1 - estimated number of consumers; b - the rate of hot water consumption per consumer, adopted according to the relevant tables of SNiPa IIG.8–62 and for apartment-type residential buildings equipped with bathrooms from 1500 to 1700 mm in length, is 110–130 l/day; 65 - hot water temperature, °C; t x - cold water temperature, °C, we accept t x = 5°C.

Thus, the maximum hourly heat consumption for DHW will be equal to:

.

It is easy to see that this result almost coincides with the result obtained using the current method.

Application of the hot water consumption rate per inhabitant per hour of greatest water consumption (for example, for “Apartment-type residential buildings with bathtubs from 1500 to 1700 mm long” q hhr == 10 l/h), given in the mandatory Appendix 3 SNiP 2.04.01–85* “Internal water supply and sewerage of buildings”, is illegal for determining the heat consumption for the needs of hot water supply by multiplying it by the number of inhabitants and the temperature difference (enthalpies) of hot water and cold water. This conclusion is confirmed both by the given calculation example and by a direct indication of this in the educational literature. For example, in the textbook for universities “Heat supply”, ed. A.A. Ionin (M.: Stroyizdat, 1982) on page 14 we read: “...Maximum hourly water consumption G h. max cannot be mixed with the water consumption given in the standards at the hour of greatest water consumption G i.ch. The latter, as a certain limit, is used to determine the probability of operation of water-folding devices and becomes equal to G h. max only with an infinitely large number of water taps.” Calculation using the old method gives a much more accurate result, provided that daily hot water consumption rates are used at the lower limit of the ranges given in the corresponding tables of the old SNiP than the “simplified” calculation that many calculators perform using current SNiP.
The data from the table in Appendix 3SNiP 2.04.01–85* must be used specifically to calculate the probability of operation of water-folding devices, as required by the methodology outlined in Section 3 of this SNiP, and then determine bhr and calculate the heat consumption for the needs of hot water supply. In accordance with the note in paragraph 3.8 of SNiP 2.04.01–85*, for auxiliary buildings of industrial enterprises the value q hr can be determined as the sum of water costs for using a shower and household and drinking needs, taken according to the mandatory Appendix 3 according to the number of water consumers in the most numerous shift.

The main parameters of residential buildings are water supply, sewer system and delivery electrical energy. Regardless of the number of residents ( a private house or multi-storey), the calculation of the main networks must be carried out according to certain rules, using the appropriate formulas. To create the right electrical diagram It doesn’t take much time; it’s much harder to decide on the water supply. A particular difficulty is the design and calculation of hot water supply. In order to carry out all operations correctly, you need to know not only the technical side of the issue, but also the regulatory framework.

The most commonly chosen type of network is the circulation type. The principle of operation of such a system is the constant circulation of liquid. The only drawback circulation system hot water supply is too expensive. The costs are only justified when the maximum number of users for a residential building is reached.

Also, in addition to the high pricing policy, constant circulation of water leads to significant heat losses, which entails additional costs. If there is a circulation system, designers try to reduce the length of the pipeline as much as possible. This option allows for additional savings on liquid transportation.

What is the waiting period and how is it calculated?

The waiting period is the time period that passes from the time the user opens the tap until hot water is supplied. They try to reduce this time as much as possible; for this purpose, the hot water supply system is optimized, adjustments are made, and if the indicators are poor, they are modernized.

To set the waiting period, generally accepted standards are used. To calculate it correctly, you should know the following:

• To reduce the waiting period, you should create high pressure water in the system. But setting too high pressure parameters can lead to damage to the pipeline.
• To reduce the waiting period, increase throughput device through which the user receives liquid.
• The waiting period increases in direct proportion to the internal diameter of the pipeline, as well as if there is a circuit at a large distance from the consumer.

The correct sequence for calculating the waiting period is:

• Determination of the number of consumers. After the exact figure, you should make a small reserve, since there are peak hot water consumption.
• Determination of the characteristics of the pipeline: length, internal diameter of the pipes, as well as the material from which they are made.
• Multiplying the length of the pipeline and its internal diameter by the specific volume of water, which is measured in l/s.
• Determination of the shortest and most convenient fluid path. This parameter also includes sections of the circuit located farthest from the water tap. All volumes of water are also added.
• The amount of liquid is divided by the water flow per second. When obtaining this parameter, the total fluid pressure in the system is also taken into account.

To achieve the most accurate results, you should correctly calculate the specific volume of the pipeline. The following formula is used for this:

Cs = 10 (F/100)2 3.14/4, where F is the internal diameter of the pipeline.

When determining the specific volume, you cannot use the value of both the external and nominal diameter of the pipes. This will significantly reduce the accuracy of calculations. There are tables in which the specific volume value is pre-calculated for certain materials (copper and steel).

Calculation of hot water consumption per day

The amount of hot water that the user needs per day is a parameter calculated in advance. Typically, such data is taken from tables, where they are divided by type of room and its square footage. European parameters should not be confused with those of other countries; they are strikingly different from each other.

On average, hot water consumption per person per day ranges from 25 to 50 liters. Compiling and calculating the amount of hot water per person is possible only after the status of the room or building is known.

How to calculate a pipeline

For long-term operation of a hot liquid transportation system, the pipeline should be calculated under peak load conditions. This allows you to make a certain reserve, which will eliminate the occurrence of malfunctions in the system with a sharp increase in pressure.

To calculate a pipeline, most often, ready-made diagrams and tables with relevant data are used. The material most often used is copper or galvanized steel. You should know that an important calculation parameter is the equivalent Fixture Unit. This device called a conditional element for a certain type of water folding mechanisms.

Pipeline calculation sequence:

• The calculation begins with determining the Fixture Unit parameter, which is mandatory for each water intake point.
• The main hot water transportation network is divided into separate sections (nodes). The principle is based on the design of the heating system.
• Find the total number of Fixture Units that will be located at different sites.
• Based on the total Fixture Unit amount and the building type, find estimated flow rate at each section of the system.
• Design flow, also referred to as throughput volume, is an important component in determining the diameter of the pipeline. The internal diameter of the pipes is determined under the condition that the final figures will not exceed generally established limits.

When calculating the circulation network, you can use general position, that for each Fixture Unit element there is 3 l/s. A separate point is the calculation recirculation pump, which has a certain throughput capacity. To determine this parameter, it is necessary to know the exact number of water points.

To provide the circulation network with additional savings, a thermostat is installed on the pump. The thermostat ensures that the device turns on when the temperature of the transported liquid drops. When the water temperature on the return circuit reaches a value less than the nominal value by 5 degrees, the pump turns off.

What you need to have to start calculating hot water supply

It is impossible to start calculating a hot water supply system without having technical and design documentation for the house. At the same time, the size of the house is not important; a private plot requires the same plan as a multi-story building.

The calculation begins with a certified architectural plan, on which the selected correct location buildings, as well as the placement of sanitary fixtures. The location of the house will help you choose the water supply system along the shortest route.

It is necessary to know the number of people who will live in the building. Naturally, it is impossible to find out the exact number of residents, so it is better to carry out the calculation using the maximum data. Such figures will allow you to calculate the correct time of peak loads.

Determine the location where the hot water supply equipment will be placed. This area, must be indicated on the diagram.