What is specific heat consumption for heating? In what quantities is the specific consumption of thermal energy for heating a building measured and, most importantly, where do its values \u200b\u200bare taken for calculations? In this article, we will get acquainted with one of the basic concepts of heat engineering, and at the same time study several related concepts. So, let's go.
What it is
Definition
The definition of specific heat consumption is given in SP 23-101-2000. According to the document, this is the name of the amount of heat needed to maintain a normal temperature in the building, related to a unit of area or volume and to one more parameter - degree-days of the heating period.
What is this setting used for? First of all - to assess the energy efficiency of the building (or, what is the same, the quality of its insulation) and planning heat costs.
Actually, SNiP 23-02-2003 explicitly states: the specific (per square or cubic meter) consumption of thermal energy for heating a building should not exceed the given values.
How better thermal insulation, topics less energy requires heating.
Degree day
At least one of the terms used needs clarification. What is a degree day?
This concept directly refers to the amount of heat required to maintain a comfortable climate inside a heated room in winter time. It is calculated by the formula GSOP=Dt*Z, where:
- GSOP is the desired value;
- Dt is the difference between the normalized internal temperature of the building (according to the current SNiP, it should be from +18 to +22 C) and the average temperature of the coldest five days of winter.
- Z is the length of the heating season (in days).
As you might guess, the value of the parameter is determined by the climatic zone and for the territory of Russia varies from 2000 (Crimea, Krasnodar region) up to 12000 (Chukotka Autonomous Okrug, Yakutia).
Units
In what quantities is the parameter of interest measured?
- SNiP 23-02-2003 uses kJ / (m2 * C * day) and, in parallel with the first value, kJ / (m3 * C * day).
- Along with the kilojoule, other units of heat can be used - kilocalories (Kcal), gigacalories (Gcal) and kilowatt hours (KWh).
How are they related?
- 1 gigacalorie = 1,000,000 kilocalories.
- 1 gigacalorie = 4184000 kilojoules.
- 1 gigacalorie = 1162.2222 kilowatt-hours.
In the photo - a heat meter. Heat metering devices can use any of the listed units of measurement.
Normalized parameters
For single-family one-story detached houses
For apartment buildings, hostels and hotels
Please note: with an increase in the number of floors, the heat consumption rate decreases.
The reason is simple and obvious: more object simple geometric shape, the greater the ratio of its volume to surface area.
For the same reason, specific heating costs country house decreases with increasing heated area.
Computing
It is practically impossible to calculate the exact value of heat loss by an arbitrary building. However, methods of approximate calculations have long been developed, which give fairly accurate average results within the limits of statistics. These calculation schemes are often referred to as aggregated indicator (measurement) calculations.
Along with the thermal power, it often becomes necessary to calculate the daily, hourly, annual consumption of thermal energy or the average power consumption. How to do it? Let's give some examples.
The hourly heat consumption for heating according to enlarged meters is calculated by the formula Qot \u003d q * a * k * (tin-tno) * V, where:
- Qot - the desired value for kilocalories.
- q - specific heating value of the house in kcal / (m3 * C * hour). It is looked up in directories for each type of building.
- a - ventilation correction factor (usually equal to 1.05 - 1.1).
- k is the correction factor for the climatic zone (0.8 - 2.0 for different climatic zones).
- tvn - internal temperature in the room (+18 - +22 C).
- tno - outdoor temperature.
- V is the volume of the building together with the enclosing structures.
To calculate the approximate annual heat consumption for heating in a building with specific consumption at 125 kJ / (m2 * C * day) and an area of 100 m2, located in climate zone with GSOP=6000, you just need to multiply 125 by 100 (house area) and by 6000 (heating degree-days). 125*100*6000=75000000 kJ or about 18 gigacalories or 20800 kilowatt-hours.
To recalculate the annual consumption into the average heat consumption, it is enough to divide it by the length of the heating season in hours. If it lasts 200 days, the average thermal power heating in the above case will be 20800/200/24 = 4.33 kW.
Energy carriers
How to calculate energy costs with your own hands, knowing the heat consumption?
enough to know calorific value appropriate fuel.
The easiest way to calculate the electricity consumption for heating a house: it is exactly equal to the amount of heat produced by direct heating.
Appendix 2 to the article by V.I. Livchak " A basic level of consumption of energy resources when establishing requirements for the energy efficiency of buildings”, published in the ENERGOSOVETE magazine 6/2013
SP 30.13330 contains tables A.2 and A.3 of normalized annual average daily water consumption, including hot water, l / day, per 1 inhabitant in residential buildings and per 1 consumer in public and industrial buildings. To determine the annual heat consumption for hot water supply, these indicators must be recalculated for the average estimated water consumption for the heating period.
1. Average calculated consumption per day of the heating period hot water per inhabitant in a residential building ggv.av.ot.l.l, l/day, is determined by the formula:
gguards.med.from.l.l. = agv.tab.A.2 365 / [ zfrom + a (351- zfrom)]; (A.2.1)
The same in public and industrial buildings:
ggv.av.ot.p.n/zh = agv.tab.A.3 365/351, (P.2.2)
where agv.tab.A.2 or A.3- calculated average per year daily consumption of hot water per 1 inhabitant from Table. A.2 or 1 consumer of a public and industrial building from table. A.3 SP 30.13330.2012;
365 - the number of days in a year;
351 - duration of use of centralized hot water supply during the year, taking into account the shutdown for repairs, days;
zfrom.- duration of the heating period;
a- coefficient taking into account the decrease in the level of water intake in residential buildings in the summer a= 0.9, for other buildings a = 1.
2. Specific average hourly consumption of thermal energy for hot water supply during the heating period qguards, W / m 2, is determined by the formula:
qguards = [ ggv.av.ot.p· (tguards- txv) · (1 + khl) rww] / (3.6 24 BUTh), (A.2.3)
where ggv.av.ot.p- the same as in formula (A.1) or (A.2);
tguards- the temperature of hot water, taken at the points of draw-off equal to 60°C in accordance with SanPiN 2.1.4.2496;
txv- temperature cold water, taken equal to 5°C;
khl- coefficient taking into account heat losses by pipelines of hot water supply systems; taken according to the following table A.1, for ITP residential buildings with a centralized hot water system khl= 0.2; for ITP public buildings and for residential buildings with apartment water heaters khl= 0,1;
rw- water density equal to 1 kg/l;
w- specific heat capacity of water, equal to 4.2 J/(kg °C);
BUTh- the norm of the total area of apartments per 1 inhabitant or usable area premises per 1 user in public and industrial buildings, the accepted value depending on the purpose of the building is given in Table P.2.2.
Table A.2.1. Coefficient value khl, taking into account heat losses by pipelines of hot water supply systems
Table A.2.2. The norms of daily consumption of hot water by consumers and the specific hourly value of thermal energy for its heating in the average day for the heating period, as well as the values of the specific annual consumption of thermal energy for hot water supply, based on the standard area per 1 meter for the central region with zfrom.= 214 days.
Consumers | Meter | Hot water consumption rate from Table A.2 SP 30. 13330. 2012 for the year a hot water supply , l/day | The norm of the total, usable area for 1 meter S a , m 2 /person. | Specific average hourly consumption of thermal energy for hot water supply for the heater. period q gv, W/m2 | Specific annual consumption of thermal energy for hot water supply q Guards. year, kWh / m 2 of total area |
||
Residential buildings regardless of the number of storeys with centralized hot water supply equipped with washbasins, sinks and bathtubs, with apartment pressure regulators KRD | |||||||
The same with washbasins, sinks and showers with KRD | |||||||
Residential buildings with plumbing, sewerage and baths with gas water heaters | |||||||
The same with solid fuel water heaters | |||||||
Hotels and boarding houses with bathtubs in all private rooms | |||||||
Same with showers in all private rooms | |||||||
Hospitals with sanitary facilities close to the wards | 1 sick | ||||||
Same with shared baths and showers | |||||||
Polyclinics and outpatient clinics (10 m 2 per health worker, work in 2 shifts and 6 patients per 1 worker) | 1 patient per shift | ||||||
1 worker per shift | |||||||
Kindergartens with day stay for children and canteens working on semi-finished products | 1 child | ||||||
The same with round the clock stay of children. | |||||||
The same with canteens working on raw materials and laundries. | |||||||
Comprehensive schools With showers at gymnastic halls and canteens at semi-finished products | 1 student 1 teacher | ||||||
Physical culture and health complexes with canteens on semi-finished products | |||||||
cinemas, assembly halls // theaters, clubs and leisure and entertainment establishments | 1 spectator | ||||||
Administrative buildings | 1 working | ||||||
Public catering enterprises for cooking in the dining room | 1 blue-to for 1 seat | ||||||
grocery stores | 1 working | ||||||
Stores | |||||||
Production workshops and techno-parks with heat dissipation. less than 84 kJ | 1 working | ||||||
Warehouses | |||||||
Notes: *- above the line and without the line - basic values, below the line, taking into account the equipment of apartments with water meters and from the condition that with apartment metering there is a 40% reduction in heat and water consumption. Depending on the percentage of apartments equipped with water meters: q gv.v / sch year = q guards year · (1-0.4N sq. w/s / N sq. ); where q guards year - according to the formula (A.2.4); N sq. - the number of apartments in the house; N sq. w/s - the number of apartments in which water meters are installed. 1. Water consumption rates in column 3 are established for I and II climatic regions, for regions III and IV should be taken taking into account the coefficient from table. A.2 SP 30.13330. 2. Water consumption rates are established for the main consumers and include all additional costs (for service personnel, visitors, showers for service personnel, cleaning of premises, etc.). Water consumption in group showers and foot baths in amenity premises manufacturing enterprises, for cooking at enterprises Catering, as well as hydrotherapy procedures in hydropathic clinics and cooking, which are part of hospitals, sanatoriums and clinics, should be taken into account additionally. 3. For water users civil buildings, structures and premises not listed in the table, the water consumption rates should be taken as for consumers similar in nature of water consumption. 4. At catering establishments, the number of dishes (^) sold in one working day may be determined by the formula U=2.2 n m n T ψ ; where n - number of seats; m n - number of seats accepted for canteens open type and cafe - 2; for student canteens and industrial enterprises- 3; for restaurants -1.5; T - operating time of a public catering enterprise, h; ψ - coefficient of uneven seating throughout the working day, taken: for canteens and cafes - 0.45; for restaurants - 0.55; for other public catering establishments, it is allowed to accept 1.0 when justifying. 5. In this table, the specific hourly standard of thermal energy qhw , W / m 2 for heating the hot water consumption rate on the average day of the heating period, taking into account heat losses in the pipelines of the system and heated towel rails, corresponds to the accepted value indicated in the adjacent column of the total area of \u200b\u200ban apartment in a residential building per inhabitant or usable area of \u200b\u200bpremises in a public building per patient , working, student or child, S a , m 2 / person. If in reality there is a different value of the total or usable area per person, S a. i , then the specific standard of thermal energy of this particular house qhw . i should be recalculated according to the following relationship: qhw . i = qhw . · S a / S a. i | |||||||
| free download Methodology for calculating the specific annual consumption of thermal energy for hot water supply of residential and public buildings, V.I. Livchak,
Heating systems and supply ventilation must work in buildings at average daily outdoor temperatures tn.day from +8С and lower in areas with design outdoor air temperature for heating design up to -30С and at tn.day from +10С and lower in areas with design outdoor air temperature for heating design below - 30C. The values of the duration of the heating period No and the average outdoor temperature tn.av are given in and for some cities of Russia in Appendix A. For example, for Vologda and adjacent areas No = 250 days / year, and tn.av = - 3.1С at tn.day=+10С.
Thermal energy consumption in GJ or Gcal for heating and ventilation of buildings for a certain period (month or heating season) is determined by the following formulas
Qo.= 0.00124NQo.r(tin - tn.av)/(tin - tn.r),
Qin. \u003d 0.001ZinNQin.r (tin - tn.av) / (tin - tn.r),
where N is the number of days in the billing period; for heating systems N is the duration of the heating season No from Appendix A or the number of days in a particular month Nmonth; for supply systems ventilation N is the number of working days of an enterprise or institution during the month Nm.v or the heating season Nv, for example, with a five-day working week Nm.v = Nmonth5/7, and Nv = No5/7;
Qо.р, Qв.р - design heat load (maximum hourly consumption) in MJ/h or Mcal/h for heating or ventilation of the building, calculated by formulas.
tvn - the average air temperature in the building, given in Appendix B;
tn.av - the average outdoor temperature for the period under consideration (heating season or month), taken according to or according to Appendix B;
tn.r - design outdoor air temperature for heating design (the temperature of the coldest five-day period with a security of 0.92);
Zв - the number of hours of operation of supply ventilation systems and air curtains during the day; for one-shift work of a workshop or institution, Zv = 8 hours/day, for two-shift operation - Zv = 16 hours/day, in the absence of data for the microdistrict as a whole Zv = 16 hours/day.
The annual heat consumption for hot water supply Qgw.year in GJ/year or Gcal/year is determined by the formula
Qgw.year = 0.001Qday (Nz + Nl Kl),
where Qday - daily heat consumption for hot water supply of the building in MJ / day or Mcal / day, calculated by the formula;
Nz - the number of days of hot water consumption in the building for the heating (winter) period; for residential buildings, hospitals, grocery stores and other buildings with daily operation of hot water supply systems, Nz is taken equal to the duration of the heating season No; for enterprises and institutions, Nz is the number of working days during the heating season, for example, with a five-day working week, Nz = No5/7;
Nl - the number of days of hot water consumption in the building during the summer period; for residential buildings, hospitals, grocery stores and other buildings with daily operation of hot water supply systems Nl \u003d 350 - No, where 350 is the estimated number of days in a year of operation of HW systems; for enterprises and institutions Nl is the number of working days during summer period, for example, with a five-day working week Nl \u003d (350 - No) 5/7;
Kl - coefficient taking into account the reduction in heat consumption for HW due to the higher initial temperature of the heated water, which is equal to tx.z = 5 degrees in winter, and on average tx.l = 15 degrees in summer; in this case, the coefficient Kl will be equal to Kl \u003d (tg - tx.l) / (tg - tx.z) \u003d (55 - 15) / (55 - 5) \u003d 0.8; when water is taken from wells, it may turn out to be tx.l = tx.s and then Kl = 1.0;
The coefficient that takes into account the possible decrease in the number of hot water consumers in the summer due to the departure of part of the residents from the city on vacation and is assumed to be = 0.8 for the housing and communal sector (for resort and southern cities = 1.5), and for enterprises = 1.0.
The procedure for calculating heating in housing stock depends on the availability of metering devices and on how the house is equipped with them. There are several options for completing multi-apartment residential buildings with meters, and according to which, heat energy is calculated:
- the presence of a common house meter, while apartments and non-residential premises are not equipped with metering devices.
- heating costs are controlled by a common house device, and all or some rooms are equipped with metering devices.
- there is no general house device for fixing the consumption and consumption of thermal energy.
Before calculating the number of gigacalories spent, it is necessary to find out the presence or absence of controllers in the house and in each individual room, including non-residential ones. Let's consider all three options for calculating thermal energy, for each of which a specific formula has been developed (posted on the website of state authorized bodies).
Option 1
So the house is equipped control device, and some rooms were left without it. Here it is necessary to take into account two positions: the calculation of Gcal for heating an apartment, the cost of thermal energy for general house needs (ODN).
AT this case formula No. 3 is used, which is based on the readings of the general meter, the area of \u200b\u200bthe house and the footage of the apartment.
Calculation example
We will assume that the controller recorded the heating costs of the house at 300 Gcal / month (this information can be obtained from the receipt or by contacting management company). For example, the total area of the house, which consists of the sum of the areas of all premises (residential and non-residential), is 8000 m² (you can also find this figure from the receipt or from the management company).
Let's take the area of an apartment of 70 m² (indicated in the data sheet, rental agreement or registration certificate). The last figure, on which the calculation of payment for consumed heat energy depends, is the tariff set by authorized bodies RF (indicated in the receipt or find out in the house management company). Today, the heating tariff is 1,400 rubles/gcal.
Substituting the data in formula No. 3, we get the following result: 300 x 70 / 8,000 x 1,400 \u003d 1875 rubles.
Now you can proceed to the second stage of accounting for heating costs spent on the general needs of the house. Two formulas are required here: the search for the volume of services (No. 14) and the payment for the consumption of gigacalories in rubles (No. 10).
In order to correctly determine the volume of heating in this case, it will be necessary to sum up the area of \u200b\u200ball apartments and premises provided for common use(information provided by the management company).
For example, we have a total footage of 7000 m² (including apartments, offices, retail premises.).
Let's start calculating the payment for the consumption of thermal energy according to formula No. 14: 300 x (1 - 7,000 / 8,000) x 70 / 7,000 \u003d 0.375 Gcal.
Using formula No. 10, we get: 0.375 x 1,400 = 525, where:
- 0.375 - volume of service for heat supply;
- 1400 r. – tariff;
- 525 rubles - amount of payment.
We summarize the results (1875 + 525) and find out that the payment for heat consumption will be 2350 rubles.
Option 2
Now we will calculate payments in those conditions when the house is equipped with a common meter for heating, as well as some apartments are equipped with individual meters. As in the previous case, the calculation will be carried out in two positions (thermal energy consumption for housing and ONE).
We will need formulas No. 1 and No. 2 (accrual rules according to the testimony of the controller or taking into account the norms for heat consumption for residential premises in gcal). Calculations will be carried out in relation to the area of a residential building and an apartment from the previous version.
- 1.3 gigacalories - readings of an individual counter;
- 1 1820 r. - approved rate.
- 0.025 gcal - standard indicator of heat consumption per 1 m² of area in an apartment;
- 70 m² - area of the apartment;
- 1 400 rubles - tariff for thermal energy.
As it becomes clear, with this option, the payment amount will depend on the availability of a metering device in your apartment.
Formula No. 13: (300 - 12 - 7,000 x 0.025 - 9 - 30) x 75 / 8,000 \u003d 1.425 gcal, where:
- 300 gcal - indications of a common house meter;
- 12 gcal - the amount of thermal energy used for heating non-residential premises;
- 6,000 m² - the sum of the area of all residential premises;
- 0.025 - standard (thermal energy consumption for apartments);
- 9 gcal - the sum of indicators from the meters of all apartments that are equipped with metering devices;
- 35 gcal - the amount of heat spent on the supply of hot water in the absence of its centralized supply;
- 70 m² - area of the apartment;
- 8,000 m² - total area (all residential and non-residential premises in the house).
Please note that this option only includes real amounts of energy consumed, and if your house is equipped with a centralized hot water supply, then the amount of heat spent on hot water needs is not taken into account. The same applies to non-residential premises: if they are not in the house, then they will not be included in the calculation.
- 1.425 gcal - the amount of heat (ONE);
- 1820 + 1995 = 3,815 rubles - With individual counter.
- 2 450 + 1995 = 4445 rubles. - without individual device.
Option 3
We are left with the last option, during which we will consider the situation when there is no heat meter on the house. The calculation, as in previous cases, will be carried out in two categories (thermal energy consumption for an apartment and ONE).
We will deduce the amount for heating using formulas No. 1 and No. 2 (rules on the procedure for calculating thermal energy, taking into account the readings of individual metering devices or according to established standards for residential premises in Gcal).
Formula No. 1: 1.3 x 1,400 \u003d 1820 rubles, where:
- 1.3 gcal - readings of an individual meter;
- 1 400 rubles - approved rate.
Formula No. 2: 0.025 x 70 x 1,400 = 2,450 rubles, where:
- 1 400 rubles - approved rate.
As in the second option, the payment will depend on whether your housing is equipped with an individual heat meter. Now it is necessary to find out the amount of heat energy that was spent on general house needs, and this must be done according to formula No. 15 (volume of service for one unit) and No. 10 (amount for heating).
Formula No. 15: 0.025 x 150 x 70 / 7000 \u003d 0.0375 gcal, where:
- 0.025 gcal - standard indicator of heat consumption per 1 m² of living space;
- 100 m² - the sum of the area of \u200b\u200bthe premises intended for general house needs;
- 70 m² - the total area of the apartment;
- 7,000 m² - total area (all residential and non-residential premises).
Formula No. 10: 0.0375 x 1,400 = 52.5 rubles, where:
- 0.0375 - volume of heat (ONE);
- 1400 r. - approved rate.
As a result of the calculations, we found out that the full payment for heating will be:
- 1820 + 52.5 \u003d 1872.5 rubles. - with individual counter.
- 2450 + 52.5 \u003d 2,502.5 rubles. – without individual counter.
In the above calculations of payments for heating, data on the footage of the apartment, house, as well as on the meter indicators, which may differ significantly from those that you have, were used. All you need to do is plug your values into the formula and make the final calculation.
What is such a measuring unit as a gigacalorie? What does it have to do with traditional kilowatt-hours, in which it is calculated thermal energy? What information is necessary to have in order to correctly calculate Gcal for heating? After all, what formula should be used during the calculation? This and many other things will be discussed in today's article.
What is Gcal?
Let's start with a related definition. A calorie is a certain amount of energy that is required to heat one gram of water to one degree Celsius (at atmospheric pressure, of course). And in view of the fact that from the point of view of heating costs, say, at home, one calorie is a miserable amount, in most cases, gigacalories (or Gcal for short), corresponding to one billion calories, are used for calculations. With that decided, let's move on.
The use of this value is regulated by the relevant document of the Ministry of Fuel and Energy, issued back in 1995.
Note! The average consumption standard in Russia per one square meter is equal to 0.0342 Gcal per month. Of course, this number is subject to change different regions because everything depends on climatic conditions.
So, what is a gigacalorie if we “transform” it into more familiar values for us? See for yourself.
1. One gigacalorie equals approximately 1,162.2 kilowatt-hours.
2. One gigacalorie of energy is enough to heat a thousand tons of water to +1°C.
What is all this for?
The problem should be considered from two points of view - from the point of view of apartment buildings and private. Let's start with the first.
Multi-apartment buildings
There is nothing complicated here: gigacalories are used in thermal calculations. And if you know how much heat energy remains in the house, then you can present a specific bill to the consumer. Let's give a small comparison: if centralized heating will function in the absence of a meter, then you have to pay for the area of \u200b\u200bthe heated room. If there is a heat meter, this in itself implies wiring horizontal type(either collector or serial): two risers are brought into the apartment (for "return" and supply), and the in-house system (more precisely, its configuration) is determined by the residents. This kind of scheme is used in new buildings, thanks to which people regulate the consumption of thermal energy, making a choice between savings and comfort.
Let's find out how this adjustment is carried out.
1. Installation of a common thermostat on the "return" line. In this case, the flow rate of the working fluid is determined by the temperature inside the apartment: if it decreases, then the flow rate will increase accordingly, and if it rises, it will decrease.
2. Throttling of heating radiators. Thanks to the throttle, the patency of the heater is limited, the temperature decreases, which means that the consumption of thermal energy is reduced.
Private houses
We continue to talk about the calculation of Gcal for heating. Owners country houses they are interested, first of all, in the cost of a gigacalorie of thermal energy received from one or another type of fuel. The table below can help with this.
Table. Comparison of the cost of 1 Gcal (including transportation costs)
* - prices are approximate, as tariffs may differ depending on the region, moreover, they are also constantly growing.
Heat meters
Now let's find out what information is needed in order to calculate the heating. It is easy to guess what this information is.
1. The temperature of the working fluid at the outlet / inlet of a particular section of the line.
2. The flow rate of the working fluid that passes through the heating devices.
The flow rate is determined through the use of thermal metering devices, that is, meters. These can be of two types, let's get acquainted with them.
Vane meters
Such devices are intended not only for heating systems, but also for hot water supply. Their only difference from those meters that are used for cold water is the material from which the impeller is made - in this case it is more resistant to elevated temperatures.
As for the mechanism of work, it is almost the same:
- due to the circulation of the working fluid, the impeller begins to rotate;
- the rotation of the impeller is transferred to the accounting mechanism;
- the transfer is carried out without direct interaction, but with the help of a permanent magnet.
Despite the fact that the design of such counters is extremely simple, their response threshold is quite low, moreover, there is also reliable protection from distortion of readings: the slightest attempt to brake the impeller by means of an external magnetic field prevented by the anti-magnetic screen.
Instruments with differential recorder
Such devices operate on the basis of Bernoulli's law, which states that the speed of a gas or liquid flow is inversely proportional to its static movement. But how is this hydrodynamic property applicable to the calculation of the flow rate of the working fluid? Very simple - you just need to block her path with a retaining washer. In this case, the rate of pressure drop on this washer will be inversely proportional to the speed of the moving stream. And if the pressure is recorded by two sensors at once, then you can easily determine the flow rate, and in real time.
Note! The design of the counter implies the presence of electronics. The vast majority of these modern models provides not only dry information (temperature of the working fluid, its consumption), but also determines the actual use of thermal energy. The control module here is equipped with a port for connecting to a PC and can be configured manually.
Many readers will probably have a logical question: what if we are not talking about a closed heating system, but about an open one, in which selection for hot water supply is possible? How, in this case, to calculate Gcal for heating? The answer is quite obvious: here pressure sensors (as well as retaining washers) are placed simultaneously on both the supply and the “return”. And the difference in the flow rate of the working fluid will indicate the amount of heated water that was used for domestic needs.
How to calculate the consumed thermal energy?
If there is no heat meter for one reason or another, then the following formula must be used to calculate the heat energy:
Vx(T1-T2)/1000=Q
Let's take a look at what these conventions mean.
1. V denotes the amount of hot water consumed, which can be calculated either cubic meters or tons.
2. T1 is the temperature indicator of the hottest water (traditionally measured in the usual degrees Celsius). In this case, it is preferable to use exactly the temperature that is observed at a certain operating pressure. By the way, the indicator even has a special name - this is enthalpy. But if the desired sensor is not available, then as a basis, you can take that temperature regime, which is extremely close to this enthalpy. In most cases, the average is approximately 60-65 degrees.
3. T2 in the above formula also indicates the temperature, but already cold water. Due to the fact that to penetrate the highway with cold water- the matter is rather difficult, as this value constant values \u200b\u200bare used that can change depending on the climatic conditions on the street. So, in winter, when the heating season is in full swing, this figure is 5 degrees, and in summer, with the heating turned off, 15 degrees.
4. As for 1000, this is the standard coefficient used in the formula in order to get the result already in gigacalories. It will be more accurate than if calories were used.
5. Finally, Q is the total amount of thermal energy.
As you can see, there is nothing complicated here, so we move on. If the heating circuit closed type(and this is more convenient from an operational point of view), then the calculations must be done in a slightly different way. The formula to use for a closed building heating system, should look like this:
((V1x(T1-T)-(V2x(T2-T))=Q
Now, respectively, to decryption.
1. V1 denotes the flow rate of the working fluid in the supply pipeline (not only water, but also steam can act as a source of thermal energy, which is typical).
2. V2 is the flow rate of the working fluid in the "return" pipeline.
3. T is an indicator of the temperature of the cold liquid.
4. T1 - water temperature in the supply pipeline.
5. T2 - temperature indicator, which is observed at the outlet.
6. And, finally, Q is all the same amount of thermal energy.
It is also worth noting that the calculation of Gcal for heating in this case is based on several designations:
- thermal energy that entered the system (measured in calories);
- temperature indicator during the removal of the working fluid through the "return" pipeline.
Other ways to determine the amount of heat
We add that there are also other ways by which you can calculate the amount of heat that enters the heating system. In this case, the formula not only differs slightly from those given below, but also has several variations.
((V1x(T1-T2)+(V1-V2)x(T2-T1))/1000=Q
((V2x(T1-T2)+(V1-V2)x(T1-T)/1000=Q
As for the values of the variables, they are the same here as in the previous paragraph of this article. Based on all this, we can make a confident conclusion that it is quite possible to calculate the heat for heating on our own. However, at the same time, one should not forget about consulting with specialized organizations that are responsible for providing housing with heat, since their methods and principles for making calculations may differ, and significantly, and the procedure may consist of a different set of measures.
If you intend to equip a "warm floor" system, then prepare for the fact that the calculation process will be more complicated, since it takes into account not only the features of the heating circuit, but also the characteristics electrical network, which, in fact, will heat the floor. Moreover, the organizations that install this kind of equipment will also be different.
Note! People often face the problem when calories should be converted to kilowatts, which is explained by the use of a unit of measurement in many specialized manuals, which is called "Ci" in the international system.
In such cases, it must be remembered that the coefficient due to which kilocalories will be converted to kilowatts is 850. If we talk more plain language, then one kilowatt is 850 kilocalories. This option the calculation is simpler than the above, since it is possible to determine the value in gigacalories in a few seconds, since Gcal, as noted earlier, is a million calories.
To avoid possible errors, do not forget that almost all modern heat meters work with some error, albeit within the allowable. Such an error can also be calculated with your own hands, for which you must use the following formula:
(V1- V2)/(V1+ V2)x100=E
Traditionally, now we find out what each of these variable values means.
1. V1 is the flow rate of the working fluid in the supply pipeline.
2. V2 - a similar indicator, but already in the "return" pipeline.
3. 100 is the number by which the value is converted to a percentage.
4. Finally, E is the error of the accounting device.
According to operational requirements and standards, the maximum permissible error should not exceed 2 percent, although in most meters it is somewhere around 1 percent.
As a result, we note that a correctly calculated Gcal for heating can significantly save money spent on heating a room. At first glance, this procedure is quite complicated, but - and you saw it for yourself - with good instructions, there is nothing difficult in it.
Video - How to calculate heating in a private house
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