Calculation of payment for hot water supply

The average consumption of thermal energy for hot water supply to the consumer is determined by formulas 20 and 21

(20)

(21)

where: Qgvz, Qgvl - the average heat consumption for direct hot water supply to the consumer without taking into account heat losses, respectively, in winter and summer, W;

a - the rate of water consumption for hot water supply, l / day person, approved by local authorities or administrations. In the absence of approved norms, it is accepted according to the application in accordance with SNiP 2.04.01-85;

m is the number of measurement units per day (number of residents, students in educational institutions, places in hospitals)

txz, tchl - the average temperature of cold (tap) water, respectively, in winter and summer, °C. It is taken during the heating season txz=5oC, in the summer period txl=15oC;

c - specific heat capacity of water, in calculations we take equal to 4.187 kJ / (kg oC)

0.28 is the conversion factor for the dimensions of physical quantities.

Note: we find the number of residents of residential buildings based on the calculation of n + 1 people per n-room apartment, for the rest of the buildings we find according to Appendix B based on the volume of the building given to us and the results obtained empirically for buildings of a different volume, but of the same type.

m - find by the formula:

m=V/in (22)

where: m is the number of units of measurement related to days;

V is the volume of the building in terms of external measurement, m3;

c - obtained by experience obtained by application

Table 5.1 - average heat consumption for hot water supply in summer for various types of buildings

building type	a, l/day person	m, units	Qavz, W	Qavl, W
Residential building 9 floors	120	297	87047,73	69638,18
Residential building 5 floors	120	165	48359,85	38687,88
Residential building 12 floors	120	132	38687,88	30950,3
Administrative buildings	7	132	2256,79	1805,43
Cinemas	5	600	7327,25	5861,8
Theaters	5	750	9159,06	7327,25
Kindergartens	30	139	10184,87	8147,90
Schools	8	100	1953,93	1813,28
Polyclinics	6	972	14244,17	11395,33
Hospitals	180	224	98478,24	78782,59
Hotels	200	225	109908,75	87927,00

The required amount of heat for the needs of hot water supply for a certain period is determined by the formula:

(23)

where: nз, nл - the number of hours of operation of the hot water supply system per day, respectively, in the winter and summer periods, h.

zз, zл - the duration of the hot water supply system

respectively in winter and summer periods, days.

The calculated values ​​of the required amount of heat for the needs of hot water supply for a certain period are shown in Table 5.2.

Table 5.2 - Calculated values ​​of the required amount of heat for the needs of hot water supply for various types of buildings

building type	Qavz, W	nz, h	zz, days	Qavl, W	nl, h	zl, days	Qgw, gJ
Residential building 9 floors	87047,73	24	250	69638,18	24	85	2391,65
Residential building 5 floors	48359,85	24	250	38687,88	24	85	1328,70
Residential building 12 floors	38687,88	24	250	30950,3	24	85	1062,96
Administrative buildings	2256,79	12	250	1805,43	12	85	31,00
Cinemas	7327,25	16	250	5861,8	16	85	134,21
Theaters	9159,06	5	250	7327,25	5	25	44,51
Kindergartens	10184,87	16	250	8147,90	16	85	186,55
Schools	1953,93	12	250	1813,28	12	25	23,06
Polyclinics	14244,17	12	250	11395,33	12	85	195,68
Hospitals	98478,24	24	250	78782,59	24	85	2705,71
Hotels	109908,75	24	250	87927,00	24	85	3019,76

Note: the number of days of hot water supply in summer for residential buildings, office buildings, cinemas, kindergartens, clinics, hospitals and hotels is determined by the formula:

Zl=365-Zht-30

where: Zht is the duration of the heating season in days;

30 - the number of days allotted for the repair of the heating main.

For schools and theaters, the number of days of hot water supply in summer is determined by the formula:

Zl=365-Zht-30-60

where: Zht is the duration of the heating season in days;

30 - the number of days allotted for the repair of the heating main.

60 - summer vacation (tour).

Determining the load on the DHW source.

Table 5.3 - Calculated values ​​of the heat load on the source of hot water supply

building type	Qgw, gJ	Number of buildings, pcs	Qgvs total, gJ
Residential building 9 floors	1700	17	40658,11
Residential building 5 floors	944,45	14	18601,75
Residential building 12 floors	75,56	7	7440,7
Administrative buildings	30,36	3	93,00861
Cinemas	262,35	2	268,4235
Theaters	86,65	1	44,51303
Kindergartens	182,18	4	746,217
Schools	60,86	5	115,3039
Polyclinics	191,28	2	391,3614
Hospitals	2646,99	1	2705,709
Hotels	2957,46	1	3019,765

(25)

General principles for performing Gcal calculations

The calculation of kW for heating involves the performance of special calculations, the procedure for which is regulated by special regulations.The responsibility for them lies with the communal organizations that are able to help in the performance of this work and give an answer on how to calculate Gcal for heating and decipher Gcal.

Of course, such a problem will be completely eliminated if there is a hot water meter in the living room, since it is in this device that there are already pre-set readings that display the received heat. By multiplying these results by the established tariff, it is fashionable to obtain the final parameter of the consumed heat.

3 Total heat consumption and gas consumption

A boiler is selected for design
double-circuit. When calculating gas consumption
it is taken into account that the boiler for heating and
DHW works separately, that is, with
turning on the DHW circuit heating circuit
turns off. So the total heat consumption
will be equal to the maximum flow. V
In this case, the maximum flow
heat for heating.

1. ∑Q = Q_omax= 6109 kcal/h

2. Determine the gas flow rate by the formula:

V=∑Q /( η ∙Q_nR),
(3.4)

where Q_np=34
MJ / m3 \u003d 8126 kcal / m3 - the lowest
heat of combustion of gas;

η – boiler efficiency;

V= 6109/(0.91/8126)=0.83 m3/h

For the cottage choose

1. Boiler
double-circuit AOGV-8,
thermal power Q=8 kW, gas consumption
V=0.8 m3/h,
nominal inlet pressure of natural
gas Рnom=1274-1764 Pa;

2.
Gas stove, 4 burners, GP 400
MS-2p, gas consumption V=1.25m3

Total gas consumption for 1 house:

Vg =N∙(Vpg
∙Ko +V2-boiler
∙ K_cat), (3.5)

where Ko \u003d 0.7-coefficient
simultaneity for gas stove
accepted according to the table depending
from the number of apartments;

TO_cat=1- simultaneity factor
for the boiler according to table 5;

N is the number of houses.

Vg =1.25∙1+0.8∙0.85 =1.93 m3/h

For 67 houses:

Vg \u003d 67 ∙ (1.25 ∙ 0.2179 + 0.8 ∙ 0.85) \u003d 63.08
m3/h

similar

	Ministry of Education and Science, Youth and Sports of Ukraine National Metallurgical Academy of UkraineGichev Yu. A. Heat supply sources for industrial enterprises. Part I: Lecture notes: Dnepropetrovsk: NmetAU, 2011. - 52 p.		Ministry of Education and Science of Ukraine Ministry of Industrial Policy of Ukraine National Metallurgical Academy of Ukraine - State Institute for Training and Retraining of Industrial Personnel (hypoprom) Under the editorship of Professor Shestopalov G.move to 0-16320291
	Ministry of Education and Science of Ukraine Ministry of Industrial Policy of Ukraine Educational and Scientific Complex "National Metallurgical Academy of Ukraine State Institute for Training and Retraining of Industrial Personnel (Hypoprom)" Edited by Professor Shestopalov G.move to 0-3612123		Ministry of Education and Science, Youth and Sports of Ukraine National University of Physical Education and Sports of UkraineThe work was carried out at the National University of Physical Education and Sports of Ukraine, the Ministry of Education and Science, Youth…
	Ministry of Education and Science, Youth and Sports of UkraineMinistry of Education and Science, Youth and Sports of Ukraine, Sevastopol National Technical University (Sevntu) from 23 to…		Ministry of Education and Science, YOUTH AND SPORTS OF UKRAINE Ministry of Education and Science, Youth and Sports of the Autonomous Republic of Crimea Republican Higher Educational Institution "Crimean Humanitarian University" (Yalta) Institute of Economics and Management
	Ministry of Education and Science of Ukraine Ministry of Industrial Policy of Ukraine National Metallurgical Academy of Ukraine - State Institute for Training and Retraining of Industrial Personnel (hypoprom) Under the editorship of Professor Shestopalov G.Sociology. Course of lectures // Shestopalov G. G., Amelchenko A. E., Kurevina T. V., Laguta L. N., edited by Prof. G. G. Shestopalov. - Dnepropetrovsk: ...		National University of Physical Education and Sports of Ukraine Lyudmila Anatoliivna GridkoThe work was carried out at the National University of Physical Education and Sports of Ukraine, the Ministry of Education and Science, Youth…
	National University of Physical Education and Sports of UkraineThe work was carried out at the National University of Physical Education and Sports of Ukraine, the Ministry of Education and Science, Youth…		National University of Physical Education and Sports of UkraineThe work was carried out at the National University of Physical Education and Sports of Ukraine, the Ministry of Education and Science, Youth…

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Other ways to calculate the amount of heat

It is possible to calculate the amount of heat entering the heating system in other ways.

The calculation formula for heating in this case may differ slightly from the above and have two options:

1. Q = ((V1 * (T1 - T2)) + (V1 - V2) * (T2 - T)) / 1000.
2. Q = ((V2 * (T1 - T2)) + (V1 - V2) * (T1 - T)) / 1000.

All values ​​of the variables in these formulas are the same as before.

Based on this, it is safe to say that the calculation of kilowatts of heating can be done on your own. However, do not forget about consulting with special organizations responsible for supplying heat to dwellings, since their principles and calculation system can be completely different and consist of a completely different set of measures.

Having decided to design a so-called “warm floor” system in a private house, you need to be prepared for the fact that the procedure for calculating the volume of heat will be much more difficult, since in this case it is necessary to take into account not only the features of the heating circuit, but also provide for the parameters of the electrical network, from which and the floor will be heated. At the same time, the organizations responsible for monitoring such installation work will be completely different.

Many owners often face the problem of converting the required number of kilocalories into kilowatts, which is due to the use of many auxiliary aids of measuring units in the international system called "Ci". Here you need to remember that the coefficient that converts kilocalories to kilowatts will be 850, that is, in simpler terms, 1 kW is 850 kcal. This calculation procedure is much simpler, since it will not be difficult to calculate the required amount of gigacalories - the prefix "giga" means "million", therefore, 1 gigacalorie - 1 million calories.

In order to avoid errors in calculations, it is important to remember that absolutely all modern heat meters have some error, and often within acceptable limits. The calculation of such an error can also be done independently using the following formula: R = (V1 - V2) / (V1 + V2) * 100, where R is the error of the common house heating meter

V1 and V2 are the parameters of water consumption in the system already mentioned above, and 100 is the coefficient responsible for converting the obtained value into a percentage. In accordance with operating standards, the maximum allowable error can be 2%, but usually this figure in modern devices does not exceed 1%.

How to calculate the cost of hot water

According to Decree No. 1149 of the Government of the Russian Federation (dated November 08, 2012), the calculation of the cost of hot water is carried out according to a two-component tariff for closed and open heat supply systems:

• in open - using components for the coolant and for thermal energy (according to article 9, paragraph 5 of the Federal Law No. 190);
• in closed ones - using components for cold water and for thermal energy (according to article 32, paragraph 9 of the Federal Law No. 416).

The invoice format has also changed with the division of the service into two lines: the consumption of hot water supply (in tons) and heat energy - Q. Before that, the tariff for hot water supply (hot water supply) was calculated for 1 m3, already including the cost of this volume of cold water and heat energy spent for heating it.

Calculation Order Dependence

Depending on the price of the components, the estimated cost of 1 m3 of hot water supply is determined.For the calculation, consumption standards in force in the territory of the municipality are used.

The procedure for calculating the cost of hot water according to the meter depends on:

• type of heating system at home,
• the presence (absence) of a common house appliance, its technical characteristics, which determine whether it can distribute Q for the needs of water supply and heating,
• the presence (absence) of individual devices,
• suppliers of thermal energy and coolant.

The division into price per cubic meter of cold water and heating costs, among other things, should encourage management companies serving the housing stock to deal with direct heat losses - to insulate risers. For owners, two-component billing means that the payment for 1 m3 of hot water supply may vary relative to the normative in case of excess consumption Q in fact.

Multi-apartment buildings without building flow meters

Quantity Q for heating 1 m3 of hot water is determined according to the recommendations of the State Committee for Tariffs, according to which the amount of heat energy is calculated by the formula: Q = c * p * (t1– t2) * (1 + K).

In this formula, according to the consumed cubic meters, the heat loss coefficient on the pipelines of the centralized hot water supply is taken into account.

• С – heat capacity of water (specific value): 1×10-6 Gcal/kg. x 1ºC;
• P is the weight of water (by volume); 983.18 kgf/m3 at t 60° C;
• t1 is the average annual temperature of DHW from centralized systems, taken as 60°C (the indicator does not depend on the heat supply system);
• t2 is the average annual temperature of cold water from centralized systems, taken according to the actual data of those enterprises that supply cold water to organizations preparing hot water (for example, 6.5°C).

Based on this, in the following example, the amount of heat energy will be:

Q=1*10-6 Gcal/kg * 1ºC * 983.18 kgf/m3 * 53.5°C * (0.35 + 1) = 0.07 Gcal/m³

Its cost for 1 m3:

1150 RUB/Gcal (DHW tariff) * 0.07 Gcal/m³ = 81.66 RUB/m³

DHW tariff:

RUB 16.89/m³ (CWS component) + RUB 81.66/m³ = RUB 98.55/m³

Example No. 2 of calculation without taking into account the heat loss coefficient on centralized pipelines for one person (without an individual water meter):

0.199 (Gcal - the standard for DHW consumption per person) * 1540 (rubles - the cost of 1 Gcal) + 3.6 (m3 - the standard for DHW consumption per person) * 24 (rubles - the cost of m3) = 392.86 rubles.

Multi-apartment buildings with house flow meters

The actual payment for hot water in houses equipped with common house meters will change monthly, depending on the volumetric indicators of thermal energy (1 m3), which, in turn, depend on:

• the quality of the metering device,
• heat loss in hot water networks,
• excess supply of coolant,
• the degree of adjustment of the optimal flow rate Q, etc.

In the presence of individual and common house appliances, payment for hot water supply is calculated according to the following algorithm:

1. The readings of the house flow meter are taken according to two indicators: A - the amount of thermal energy and B - the amount of water.
2. The amount of thermal energy spent per 1 m3 of coolant is calculated by dividing A by B \u003d C.
3. Readings of the apartment water meter are taken in m3, which are multiplied by the result C to get the Q dimension for the apartment (D value).
4. The value of D is multiplied by the tariff.
5. A component is added to heat the coolant.

Example when consuming 3 m3 according to the apartment meter:

At the same time, if it is difficult to influence the results of general house readings by the forces of one apartment, then the readings of individual water meters can be influenced by legal methods, for example, by installing water savers: http://water-save.com/.

Read more

Heat meter calculation

Calculation of the heat meter consists in choosing the size of the flow meter. Many mistakenly believe that the diameter of the flowmeter must match the diameter of the pipe on which it is installed.

The diameter of the heat meter flow meter should be selected based on its flow characteristics.

• Qmin — minimum flow, m³/h
• Qt - transition flow, m³/h
• Qn - nominal flow, m³/h
• Qmax — maximum allowable flow, m³/h

0 - Qmin - the error is not standardized - long-term operation is allowed.

Qmin - Qt - error not more than 5% - long-term operation is allowed.

Qt – Qn (Qmin – Qn for flowmeters of the second class for which the Qt value is not specified) – error not more than 3% – continuous operation is allowed.

Qn - Qmax - error not more than 3% - work is allowed no more than 1 hour per day.

It is recommended to select flow meters of heat meters in such a way that the calculated flow rate falls within the range from Qt to Qn, and for flow meters of the second class for which the Qt value is not specified, in the flow range from Qmin to Qn.

In this case, one should take into account the possibility of reducing the coolant flow through the heat meter, associated with the operation of control valves and the possibility of increasing the flow through the heat meter, associated with the instability of the temperature and hydraulic conditions of the heating network. It is recommended by regulatory documents to select a heat meter with the closest value of the nominal flow rate Qn to the calculated flow rate of the coolant. Such an approach to the choice of a heat meter practically excludes the possibility of increasing the coolant flow rate above the calculated value, which quite often has to be done in real heat supply conditions.

The above algorithm displays a list of heat meters that, with the declared accuracy, will be able to take into account the flow rate one and a half times higher than the calculated one and three times less than the calculated flow rate. The heat meter chosen in this way will allow, if necessary, to increase the consumption at the facility by one and a half times and reduce it by three times.

For high-speed water heaters is determined by the formula

=

where
_b,
_m
– large and small temperature difference
between heat carriers and heated
water at the ends of the water heater.

More often
total speed water heater
works according to the countercurrent scheme (cold
water meets the cooled coolant,
and heated - hot).

Wherein

_b
= t_n
– t_G
(or t_To
-t_X)

_m
= t_To
– t_X
(or t_n
– t_G)

where t_n
and t_To
- initial and final temperature
coolant

t_G
and t_X
start and end temperature
heated water ( t_X
= 5,
t_G
= 75
)

_b=
60-5 = 55

_m
= 90-75=15

==
0,48

Let's define
required heating surface
water heaters

=
666.4 m2

Calculate
required heating surface
water heater, determine the required
number of heater sections

where
—
the required number of sections of the received
water heater (rounded to the nearest integer)
number of sections up)

—
heating surface area
sections (we take from appendix 6)

=3,54

=298
section

Task #4

Make a hydraulic calculation
yard sewer network
wastewater from a residential building to a city
network, according to the given option
master plan.

The surface of the land -
horizontal.

Initial data	Number option
1	8
Option yard sewer master plan		1
*Number taps in building N	192
*Number U residents	144
*norm consumption of cold and hot water per hour highest water consumption q l	14,3
mark ground surface		51
mark yard sewer pipe tray nets in the first well		49
mark city ​​sewer pipe tray		48
Length plots:
l, m		25
l, m		8
l, m		13
l, m		—

		III
			K2
	K1	l2
		line	QC
		G QC		l3

K1 -
yard sewer-

valuable
well

QC
– control sewer well.

GKK
– city sewer

rational
well

The main purpose of the hydraulic
calculation of the yard sewer network
is the choice of the smallest slope
pipes, which provides
passage of the estimated flow of sewage
liquids with a speed of at least 0.7
(speed of self-cleaning). At speed
less than 0.7
possible deposition of solid cock and
blockage of the sewer line.

Preferably
so that the yard network has the same
slope throughout. Least
the slope of pipes with a diameter of 150 mm is
0.008. The largest slope of sewer pipes
network should not exceed 0.15. wherein
pipe filling must be at least
0.3 diameter. Permissible maximum
filling pipes with a diameter of 150 - 300 mm is not
more than 0.6.

Hydraulic calculation follows
produce according to tables, assigning
fluid velocity v,
m/_With
and filling h/_d
so that in all areas
condition was met:

v0,6

Design area number	Section length, m	Number of sanitary appliances in this section N, PC.	NPtot		Total consumption of cold and hot water in the design section qtot l/s	Waste liquid consumption for calculation section qs l/s	Pipe diameter d, mm	Pipe slope, i	Sewage flow rate liquids, v, m/s	Pipe filling, h/d	v	mark pipe trays in sections, m	Tray mark difference plot, m
At the beginning	In the end
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
1	25	96	0,95	0,942	1,41	3,01	150	0,014	0,72	0,28	0,4	49	48,65	0,35
2	8	192	1,9	1,394	2,1	3,7	150	0,03	1,01	0,26	0,5	48,65	48,41	0,24
3	13	192	1,9	1,394	2,1	3,7	150	0,03	1,01	0,26	0,5	48,41	48	0,41

For plots, the value of ptot
determined by the formula

where

general
water consumption rate, l/s;

general
standard water consumption of one device,
l/s.

U– number of water consumers:

=
0.3 m/s

For
first section:

NPtot
= 96∙0,00993= 0,95

α=0.942

q=5

,

q=5*0,3*0,942
= 1.41 l/s

For
second and third sections:

NPtot
= 192∙0,00993= 1,9

α=1.394

q=5

,

q=5*0,3*1,394
= 2.1 l/s

Maximum
second wastewater flow qs
l / s, in the settlement area

q=
qtot+q

q
= 1.6 l/s
appliance (toilet flush tank)

For
first section:

q=
1.41 + 1.6 = 3.01 l/s

For
second and third sections:

q=
2.1 + 1.6 = 3.7 l/s

Conclusion on the topic

For ordinary consumers, non-specialists who do not understand the nuances and features of heat engineering calculations, everything that has been described above is a difficult topic and somewhere even incomprehensible. And it really is. After all, it is quite difficult to understand all the intricacies of the selection of one or another coefficient. That is why the calculation of thermal energy, or rather, the calculation of its amount, if such a need arises, is best entrusted to a heating engineer. But it is impossible not to make such a calculation. You yourself could see for yourself that a fairly wide range of indicators depend on it, which affect the correct installation of the heating system.