Calculation of a two -pipe heating system

For both comfort and energy efficiency, you must make sure your house stays warm and comfortable throughout the colder months. An efficient heating system’s design is essential, especially the arrangement and arrangement of the pipes that provide hot water or steam to every part of the house. We’ll go into the nuances of calculating a two-pipe heating system in this article, explaining what it is, how it operates, and why many homes choose it.

Let’s start by defining a two-pipe heating system in detail. A two-pipe system has separate pipes for supply and return, in contrast to its single-pipe counterpart, which uses a single pipe for both the supply and return of water or steam from the radiators. Better temperature control, more uniform heat distribution, and the capacity to individually control every radiator or zone in the house are just a few benefits of this design.

To achieve maximum performance and efficiency, a two-pipe heating system’s calculation must carefully take into account a number of different factors. Determining the ideal pipe size and arrangement is essential to providing enough heat to every room while reducing energy waste. These figures take into account various factors, including the size of the home, the amount of insulation, the local climate, and the kind of heating system.

Furthermore, to guarantee uniform heat distribution and avoid any regions from overheating or underheating, the design of a two-pipe heating system necessitates balancing the flow of hot water or steam throughout the network of pipes. To accomplish the appropriate temperature comfort levels in each room, this entails figuring out the right flow rates, pipe diameters, and radiator sizes.

When installing or replacing their heating systems, homeowners can make well-informed decisions if they comprehend the basic concepts underlying the calculation of a two-pipe heating system. Having a well-designed and balanced heating system is crucial for generating a comfortable living space, optimizing energy efficiency, and lowering utility costs, whether you’re building a new house or remodeling an old one.

Hydraulic calculation of the heating system, taking into account pipelines

Heating system layout featuring an open expansion tank and pumping circulation.

The primary hydraulic parameters—the hydraulic resistance of the reinforcement and pipelines, the coolant’s flow rate and speed, the table, and the program—will be utilized in all computations. There is a full relationship between such parameters. You must rely on this when doing computations.

Example: if you increase the speed of the heat carrier, the hydraulic resistance of the pipeline will also increase. If the heat carrier consumption is increased, the coolant rate and hydraulic resistance can increase at the same time. The larger the diameter of the pipeline will be, the smaller the speed of the coolant and hydraulic resistance. Based on the analysis of such relationships, it is possible to turn a hydraulic calculation into an analysis of reliability and efficiency parameters of the entire system, which can help reduce the costs of materials that are used. It is worth remembering that hydraulic characteristics are not constant, which can help nomograms with.
Hydraulic calculation of the water heating system. The flow rate of the coolant

Potential layout for the two-pipe heating system in the future.

The thermal load that the coolant must withstand while heat is transferred from the heat generator to the heating device will determine the coolant flow rate. This criterion includes a program and table.

The hydraulic calculation entails figuring out the coolant flow rate relative to the specified area. A plot with a constant diameter and a steady heat carrier consumption will be used in the calculation section.

An example of a brief calculation will contain a branch that includes 10 kilowatt radiators, while the flow rate of the coolant is calculated on the transfer of thermal energy at 10 kW. In this case, the calculated section is a section from the radiator, which is the first in the branch to the heat generator. However, this is only on condition that such a section will be characterized by a constant diameter. The second section will be located between the first and second radiators. If in the first case the transfer consumption of 10-kilovatt energy of heat is calculated, then in the second section the amount of energy that is calculated will be 9 kW with a possible gradual decrease as such calculations are carried out.

System of natural circulation for heating.

The hydraulic resistance of the supply and reverse pipelines will be computed concurrently.

In order to determine the coolant flow rate for such heating, the hydraulic calculation uses the following formula for the calculated site:

G Uch is equal to (3.6*q Uch)/(c*(t r-t o)), where q q is the site’s calculated heat load (in BT). The specific heat capacity for water (C), which is 4.2 kJ (kg*° C), is constant in this example. The temperature of the coolant in the heating system is denoted by t r, and the temperature of the cold coolant is denoted by t o. Calculating the heating gravitational system hydraulically: The coolant’s flow rate

Design of the distributors’ heat supply system.

It is recommended to use a threshold value of 0.2-0.26 m/s for the minimum coolant speed. Reduced speed may cause the coolant to release too much air, which could result in air plugs. The heating system will then completely or partially fail as a result of this. In relation to the upper threshold, the coolant velocity ought to be between 0.6 and 1.5 m/s. The pipeline will not be able to produce hydraulic noises if the speed does not increase above this indicator. Experience has shown that the ideal speed range for heating systems is between 0.4 and 0.7 m/s.

The parameters of the pipeline materials in the heating system must be considered if a more precise computation of the coolant speed range is required. More precisely, internal pipeline surfaces will require a roughness coefficient. For instance, the ideal coolant speed for steel pipelines is between 0.26 and 0.5 m/s. A polymer or copper pipeline may allow for a 0.26–0.7 m/s speed increase. To be safe, you should carefully review the recommended speed listed by heating system equipment manufacturers.

The material of the pipelines used in the heating system, specifically the coefficient of roughness of the inner surface of the pipeline, will determine a more precise range for the coolant velocity, which is advised. For instance, it is advised to follow the coolant speed range of 0.26 to 0.5 m/s for steel pipelines. From 0.26 to 0.7 m/s for polymer and copper (polyethylene, polypropylene, metal-plastic pipelines). If the manufacturer’s recommendations are available, it makes sense to follow them. Pressure loss in the hydraulic resistance calculation of the heating gravitational system

The distributor "3"’s schematic for the heating system.

The total of all losses for hydraulic friction and local resistances is known as pressure losses in specific areas, which are also referred to as "hydraulic resistance." The following formula can be used to calculate such an indicator, which is measured in PA:

Ruuch is equal to r * l + ((p * v2)/2) * e3, where V is the coolant speed (measured in m/s), p is the coolant density (measured in kg/m³), r is the pipeline pressure loss (measured in pa/m), l is the estimated pipeline length on the site (measured in m), and E3 is the total of all coefficients of local resistances in the equipped area and shut-off-regulating reinforcement.

The total resistance of the calculation sections is the general hydraulic resistance. The following table (image 6) is included in the data. Calculating the hydraulics of a gravitational heating system with two pipes: Selecting the primary branch

Pipeline hydraulic calculation.

For the two-pipe system, you must choose the ring of the most loaded riser via the heating device below if the hydraulic system is defined by the coolant passing through it.

In the event that the heat carrier in a two-pipe system moves in a dead end, you will need to choose a lower heating device ring for the highest load from the farthest risers.

In the case of a horizontal heating structure, the lowest floor’s most heavily loaded branch must be selected for ring placement.

Go back to the contents table.

An example of a hydraulic calculation of a two -pipe gravitational heating system

Computation of the distributors’ heat supply system.

The horizontal two-pipe heating system comprises two distinct heating systems: the supply of heat to distributors (between distributors and thermal point) and the heating from distributors (between heating devices and the distributor). The heating devices of the system are linked to the heating system through the use of a distributor.

The heating system design is typically composed of distinct circuits:

• scheme of heating systems from distributors;
• Scheme of the heat supply system of distributors.

An illustration would be a hydraulic calculation for a two-pipe heating system in a two-story administrative building with lower wiring. The integrated top-end is where the heat supply is organized.

The available source data are as follows:

1. The calculated load of the heat of the heating system: q Zd = 133 kW.
2. Heating system parameters: t g = 75 ° C, t o = 60 ° C.
3. The calculation consumption of the coolant in the heating system: V Co = 7.6 m³/h.
4. The heating system is attached to the boilers through a hydraulic horizontal separator.
5. The automation of each boiler supports the constant temperature of the heat carrier at the output of the boiler: t g = 80 ° C throughout the year.
6. At the input of each distributor, an automatic pressure retail regulator is designed.
7. The system of heat supply of the distributors is made of steel water and gas pipes, the heating system from distributors – from metal -polymer pipes.

It is necessary to install a pump with rotation speed control for this two-pipe heating system. To select a circulating pump, you must ascertain the pressure (p n, kPa) and supply values (v n, m³/h).

The pump supply and the heating system’s computed consumption are the same:

7.6 m3/h is V n = v Co.

The total of the following factors determines the necessary pressure, p n, which is equivalent to the estimated loss of heating pressure, a P CO:

1. Losses of pressure from OA P CHD.With.T.
2. Loss of pressure of the heating system from OA P distributors.from.
3. Pressure losses in the distributor a P.

A p co = oa p = P n.+ OA P Uch.from + a p rebt + with.

In order to compute OA P Uch.With.T and OA P.You should run the heat supply system diagram and the heating circuit from the distributor "3" using the circulation calculation ring.

The thermal loads of the Q4 rooms (calculated heat-related losses) must be distributed on the heating system diagram from the "3" distributor in accordance with the heating devices, which are compiled by distributors. The calculation scheme also shows the distributors’ thermal loads.

Both boilers or just one of them can operate, depending on the necessary heat production from combustion (during the spring and summer months). Every boiler features an independent circulation circuit equipped with a P1 pump. Within this circuit, the coolant will maintain a consistent flow rate and temperature of T G = 80 ° C for a duration of one year.

A two-position temperature controller that regulates the power of the P2 pump allows the water supply in a boiler 2 to have a temperature of T G = 55 °C. The coolant circulation will supply a pump with electronic control P3 during heating. Using the observant electronic regulator 11, the heating system’s supply water temperature varies based on outside air temperature, influencing the three-way control valve.

The first direction can be used to perform the hydraulic calculation of the distributors’ heat supply system. You must select a ring through a loaded heating device of the most loaded distributor "3" in order to determine the main circulation ring.

Using a nomogram, the diameters of the main heat pipeline sections d Y, mm are chosen, with a water speed of 0.4–0.5 m/s.

The nomogram’s nature of use is illustrated by a table (section No. 1) with the formula g Uch = 7581 kg/h/h. It is advised to stick to a certain RUS REAST loss of friction and nothing more. Nomograms define Pa pressure on local resistances Z as a function z = f (oae). A table is included in the hydraulic calculation results.

For every segment of the main circulation ring, the coefficients of local OAE resistances should be added up as follows:

• Plot No. 1 (beginning from the pressure pipe of the P3 pump, without a check valve): sudden narrowing, sudden expansion, valve, OAE = 1.0 + 0.5 + 0.5 = 2.0;
• Plot No. 2: the tee of the branch, oae = 1.5;
• Plot No. 3: passing tee, divert, OAE = 1.0 + 0.5 = 1.5;
• Plot No. 4: passing tee, divert, OAE = 1.0 + 1.0 = 2.0;
• Plot No. 2: the tee on the anti -fluid, OAE = 3.0;
• Plot No. 1 to the jumper of the admixture: sudden narrowing, sudden expansion, valve, divert, oah = 1.0 + 0.5 + 0.5 + 0.5 = 2.5;
• Plot No. 1a from the jumper of the admixture to the suction pipe of the P3 pump, without a valve, without a filter: a hydraulic separator in the form of a sudden narrowing and sudden expansion, two withdrawals, two gate valves, OAE = 1.0 + 0.5 + 0.5 + 0, 5 = 2.5.

For the check valve D Y = 65 mm, GHC = 7581 kg/h on site No. 1, the manufacturer’s monogram should be used to calculate the valve resistance, which is as follows:

The bandwidth value at site No. 1a, K V = 55 m3/h, should be used to calculate the filter resistance, d = 65 mm.

(G | k v) pf = 0.1 for A. (7581 /55) 2 = 1900 PA. 2 = 0.1.

The three-way valve’s standard size is chosen, establishing the necessary value as follows: k v = (2 g… 3 g), or k v > 2. 7.58 = 15 m3/h.

We take the valve with d = 40 mm and k v = 25 m3/h.

It will encounter resistance from:

G | k v; A P CL = 0.1 2 is 0.1. (25) * (7581 /5) = 9200 PA.

As a result, the following represents the loss of heat distributor pressure supply:

OA P.With.T equals 21.5 kPa (21514 PA).

The remaining portion of the heat distributor supply is calculated using the chosen pipeline diameters in the same manner.

Using the most loaded heating device Q PR = 1500 W (branch “B”), you should choose the calculated main circulation ring for calculating the OA P Uch.With.T heating system from the “3” distributor.

The first direction is used to calculate the hydraulics.

A nomogram for metal-polymer pipes is used to choose the diameters of the thermal pipeline sections (d y, mm), and the water speed is limited to 0.5–0.7 m/s.

The figure (example of plots No. 1 and No. 4) illustrates the nomogram’s type of use. It is advised to stick to a certain RUS REAST loss of friction and nothing more.

The formula for loss of pressure on resistance z, P is z = f (oae).

Two -pipe heating system – calculation features, scheme and installation

Two-pipe heating systems continue to hold the top spots in the specialized equipment market, even in spite of single-pipe heating systems’ relatively easy installation and relatively short pipeline length.

Despite being brief, the benefits of a two-pipe heating system are compelling and significant enough to support the purchase and subsequent application of contours featuring a straight line and reverse line.

As a result, despite the fact that installing the system is not simple, many customers choose it over other models.

In setting up a heating system for your home, the calculation of a two-pipe system plays a crucial role in ensuring optimal efficiency and comfort. This system involves two pipes: one for supplying hot water to radiators or other heat emitters, and another for returning the cooler water back to the boiler for reheating. The key factors in calculating this system include the size of the pipes, the heat output required for each room, and the overall layout of the heating network. By accurately calculating these elements, homeowners can achieve balanced heat distribution, minimize energy waste, and ultimately create a cozy and cost-effective living environment. This process requires careful consideration of factors like building size, insulation quality, and local climate conditions to tailor the system to the specific needs of the home. Through proper calculation and installation, a two-pipe heating system can efficiently provide warmth and comfort throughout the house while keeping energy bills in check.

Heating with two highways

Two pipeline branches are a defining characteristic of the two-pipe heating system’s structural design.

The first one supplies water heated in the boiler to all required devices by conducting and directing it.

The other sends its heat generator after gathering and removing the water that has already cooled during the process.

In contrast to a two-pipe system, which operates through every heating device using the same temperature indicator, a single-pipe system significantly loses the features required for a stable process at the pipeline’s closing section.

When selecting a two-pipe heating system, the length of the pipes and the associated costs increase twofold; however, this is a negligible detail given the clear benefits.

First off, unlike in the case of a single-pipe contour, no pipes with a large diameter value will be required to create and mount a two-pipe structure of the heating system. As a result, no obstacles will be encountered along the route.

The cost difference will be barely noticeable because all the required fasteners, valves, and other structural components are substantially smaller in size.

One of the most significant benefits of this type of system is that it can be mounted in close proximity to each thermostat battery, which will save costs and improve operational convenience.

Furthermore, the inconspicuous branches of the serving and feedback also do not compromise the integrity of the house’s interior; instead, they can be concealed within the wall or behind the lining.

Even after deconstructing the subtleties and benefits of each heating system on the shelf, most owners still favor the two-pipe option. For such systems, however, a selection must be made from a number of options; the owners themselves determine which will be the most practical and useful in use.

Horizontal and vertical schemes

Such a heating system is split on both horizontal and vertical schemes according to where the pipeline that joins all of the devices together is located.

Unlike other heating schemes, this one has all the required equipment attached to the vertically positioned riser.

Although its compilation will come out in the end a little more, but the formed air stagnation and traffic jams will not interfere with stable work. Such a decision is the most suitable for the owners of the apartment in the house with many floors, since all individual floors are connected separately.

For a one-story residential building that is reasonably long, a two-pipe horizontal heating system works well because connecting all of the existing radiator compartments to the horizontal pipeline makes sense and is easier.

Excellent hydraulic and temperature stability is a feature shared by both variations of the heating system’s contours; in the first case, risers positioned vertically will need to be calibrated, and in the second, horizontal loops.

Wiring a two -pipe heating network and its types

There is a classification of different types of two-pipe heating system schemes based on how the wiring is assembled and installed.

The installation of an expansion capacity at the highest point of the heating circuit and the upper laying of diluting pipes are its distinctive features.

This kind of wiring is typically pre-insulated with special materials in attics. However, this view is definitely inappropriate for a one-story cottage with a typical flat roof.

One characteristic that sets this variety apart is the hot laying of the feeding line, which is typically found in a basement or subterranean space.

Additionally, the water cooled during the process is sent to the heating boiler via the reverse line’s pipes, which are situated even below the highway.

It will also be necessary to activate the air line during the installation of the lower wiring in order to remove extra air from the heating network. Additionally, since the batteries must be positioned higher to ensure a consistent supply of heat to heating devices and devices, the boiler must be positioned deeper than the pipeline in order to promote stable water movement.

The two wiring types work equally well with both horizontal and vertical heating schemes. Generally speaking, lower wiring is installed in high-rise buildings with vertical circuits.

The problem is that this leads to excessively high pressure, whose value rises with each step, due to the temperature differential between the coolant and the reverse line.

This additional pressure indicator aids in the water’s ability to pass through the pipeline in the event of lower wiring. But if, due to the complex architecture of the building, it is impossible to carry out the lower wiring, then the upper.

Additionally, since there will be a lot of sludge in the lower part of the pipeline, it is not advised to prepare and mount the reverse and supply pipeline using the upper type of heating system.

Heating pipelines are also classified according to the direction of the water supply, so they can be:

• Directly, with the same direction of water movement both in feeding and in the reverse line.
• Dead end, with different directions of the supply and reverse coolant.

The design of the heating system can be such that, as a result of the heating pipeline’s inclination and the laws of physics, the circulation happens on its own or that it is fitted with a specialized pump that promotes steady circulation.

Typically, owners who wish to extract every bit of productivity from the system fit it with a customized pump. In one-story cottages and modestly sized private homes, the structure with the coolant gravity is typically constructed.

A slope is made in the direction of the boiler’s heat-generating output when assembling and installing the horizontal wiring of the pipelines for the natural circulation heating system.

Recall that horizontal heating schemes utilizing natural water circulation in the heating system are required to have a slope, which must unquestionably cover 1% of the pipeline’s total length.

In the event of an electrical outage or malfunction, this condition will guarantee a steady flow of coolant.

Hydraulic calculation: Basic rules

The hydraulic calculation is performed using the assembled and validated heating scheme, which accounts for all integrated components and apparatus. Axonometric functions and equations are used to compute the two-pipe heating system.

Typically, the most loaded heating pipeline ring is selected and divided into suitable sections for the primary computation object.

The process yields calculations for the necessary surface area of the pipeline, the required value of the heating pipe section, and the potential pressure loss in the system circuit.

There are numerous variations on a similar hydraulic calculation; the most popular and logical ones are as follows:

• The calculation according to the indicator of linear specific pressure losses, which suggest equal fluctuations in the temperature regime in all elements and wiring devices.
• Implementation of calculations on the significance of conductivity and characteristics of the resistance of the heating system, which also suggest possible changes and changes in thermometer indicators.

When the first method’s work is finished, a distinct image with a realistic distribution of resistance indicators in the heating system’s contour is produced as a result of the computations. The second is precise information about the coolant flow rate that will occur in the future and the temperature regime values in each heating system component.

Installation of a two -pipe heating system of a house

Setting up a two-pipe system

The following legal requirements and technical specifications are followed when installing a heating system with a two-pipe type of network:

• The contour of the two -pipe system includes two heating branches: the upper with hot water and the lower with cooled.
• The bias of the pipeline from the natural circulation of the coolant towards the last battery should not be less than 1% of the entire length.

Radiators must be installed at the same level if the heating system has two parallel wings.

1. When compiling a heating system, it will be necessary to make sure that the lower gasket is symmetrical and parallel to the upper line.
2. For the necessary repair and maintenance, all closing nodes, pump, bypass and radiators must be equipped with valves.
3. Due to the need to exclude the loss of the temperature regime of the coolant in wiring, the supply pipeline must be insulated with special materials.
4. In no case should heating pipes have direct nodes and possible overlaps that create air stagnation and traffic jams.
5. In the case of the upper type of wiring, the distribution tank must be installed in the insulated attic.
6. The sizes of tees, cranes and valves must fully correspond to the parameters of the pipelines themselves.
7. For a standard steel pipeline, the fastening of the line should be ensured every 1.2 meters.

Methods for connecting the batteries in the radiator

Installing a compensatory tank, boiler, batteries, radiators, and pipeline in line with the recommended wiring scheme is all that is fundamental to mounting the heating system.

• The main pipeline supplying coolant in hot mode is diverted from the heat generator.
• The supply pipeline must be connected to a compensatory tank with a drain
• Typically, a bypass with a circular pump and valves is mounted as close as possible to the starting design point (at the exit from the room with the installed heating system)
• The upper pipeline is removed from the compensatory tank, from which all incoming radiators are laid pipe with the coolant.
• The return is carried out in parallel in relation to the highway, connected to all radiators and introduced into the lower third of the boiler.

The end result of the entire process should be a closed heating system contour that supports a stable and comfortable temperature regime in a home or apartment. Thermostats, of which the more advanced models automatically switch on or off a gas burner as needed, are required to monitor and regulate the flow of thermal energy.

See the video below to learn more helpful installation advice:

While launching a complex communication network is not an easy task, a two-pipe system can be assembled and launched at home with the help of specialized equipment and a pre-made plan that includes all the necessary details.

Component	Description
Boiler	Heats water to a set temperature.
Radiators	Distribute heat throughout the house.
Pipes	Carry hot water from the boiler to the radiators and return cooler water to the boiler.
Thermostat	Controls the boiler to maintain desired temperature.

For homeowners trying to maximize their insulation and heating system, it is essential to comprehend the nuances of a two-pipe heating system. People can learn how to maximize energy efficiency and efficiently distribute heat throughout their homes by exploring the computations involved.

A two-pipe system’s ability to provide even heating in various parts of the house is one of its main advantages. The flow rates and pipe sizes can be changed to guarantee that every room receives the right amount of heat, enhancing efficiency and comfort through accurate calculations.

Additionally, the calculations required to design a two-pipe heating system give homeowners the ability to decide on insulation with confidence. People can find areas of their homes that might benefit from extra insulation by knowing thermal conductivity and heat loss calculations. This will lower energy use and utility bills.

Moreover, the application of a thoughtfully designed two-pipe heating system can support environmental sustainability. Homeowners can lessen their carbon footprint and help with climate change efforts by maximizing heat distribution and minimizing energy waste.

To sum up, figuring out how to calculate a two-pipe heating system is essential to making sure a house is properly heated and insulated. Homeowners can minimize energy use and environmental impact while creating a comfortable living space by comprehending the concepts underlying these computations.

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