The operation of the heating elevator. What is the elevator assembly made of? The main malfunctions of the elevator assembly.
No one will argue that the heating system is one of the most important life support systems for any housing, both a private house and an apartment. If we talk about apartments, then centralized heating often prevails in them, while in private houses most often there are autonomous systems heating. In any case, the device heating system requires close attention. For example, in this article we will talk about such important element, as an elevator heating unit, the purpose of which is not known to everyone. Let's figure it out.
What is an elevator heating unit and what is it used for?
In order to clearly understand the device and the purpose of the elevator unit, you can go to a regular basement high-rise building. There, among the other elements of the thermal unit, you can find the desired part.
Consider circuit diagram supply of coolant to the heating system of a residential building. Hot water is supplied through pipelines to the house. It should be noted that there are only two pipelines, of which:
- 1- supply (brings hot water to the house);
- 2 - reverse (carries out the removal of the coolant that gave off heat back to the boiler room);
Heated to a certain temperature, water from the thermal chamber enters the basement of the building, where a shut-off valves. Previously, valves were installed everywhere as shutoff valves, now they are gradually being replaced Ball Valves made from steel. The further path of the coolant depends on its temperature.
In our country, boiler houses operate according to three main thermal regimes:
- 95(90)/70 0 С;
- 130/70 0 С;
- 150/70 0 С;
If the water in the supply pipeline is heated to no more than 95 0 C, then it is simply distributed through the heating system using a manifold equipped with control devices (balancing valves). In the event that the temperature of the heat carrier is higher than 95 0 С, then, according to the current standards, such water cannot be supplied to the heating system. You need to cool it down. This is where the elevator assembly comes into play. It should be noted that the elevator heating unit is the cheapest and in a simple way coolant cooling.
The principle of operation of the elevator heating unit and the scheme
With the help of an elevator, the temperature of the superheated water drops to the calculated value, after which the prepared coolant is sent to the heating devices. The principle of operation of the elevator unit is based on mixing in it the superheated coolant from the supply pipeline with cooled water from the return pipe.
The diagram of the elevator assembly below clearly shows that the elevator performs 2 functions at once, which improves the overall efficiency of the heating system:
- Works as a circulation pump;
- Performs the function of mixing;
The advantage of the elevator is its simple design and, despite this, its high efficiency. Its cost is low. It does not require an electrical connection to operate.
It is worth mentioning the disadvantages of this element:
- There is no possibility to control the outlet water temperature;
- The pressure difference between the supply and return pipelines must not exceed the range of 0.8-2 bar;
- Only the exact calculation of each detail of the elevator guarantees its efficient operation;
To date, elevators are still widely used in heating units of residential buildings, since their efficiency does not depend on changes in thermal and hydraulic regimes in heating networks. In addition, the elevator assembly does not require constant supervision, and to adjust it, it is enough to choose the right nozzle diameter. It is worth remembering that the entire selection of elements of the elevator assembly should be trusted only to specialists who have the appropriate permissions.
What is the elevator assembly made of?
- Jet elevator;
- Nozzle;
- resolution camera;
In addition, the elevator assembly includes the so-called “elevator piping”, consisting of control pressure gauges, thermometers, and shut-off valves. AT recent times there were elevators equipped with an electric drive to control the diameter of the nozzle. Such an elevator allows you to automatically adjust the temperature of the coolant entering the heating system. However, such models are not yet widely used due to the low degree of reliability.
Conclusion
Technologies used in the utility sector are constantly evolving. Elevators are being replaced by thermal units with automatic temperature control of the supply and return heat carriers. They are more economical, compact, but their cost is quite high compared to the elevator. In addition, they require electricity to operate.
Heating is essential system in the house, but some of its constituent elements are not known to all plumbers. One of them is the elevator heating unit, which plays an important role in the process of providing the required winter period warmth.
The elevator is a special device that performs the function of pumping equipment. You can see it by going down to the basement of a multi-storey building.
The main task of the elevator is to ensure the optimal distribution of pressure inside the heating system and set the required temperature of the coolant. In fact, the volume of coolant that flows from the boiler room through pipes increases up to 2 times. If 6 cubic meters of liquid is supplied at the inlet of the water supply, up to 12 cubic meters will enter the house system.
It is possible to achieve such indicators only if the water is in a sealed container in which high pressure. It becomes possible to avoid boiling water when its temperature reaches 100 degrees. It is heated much more (up to 150 degrees).
However, for a number of reasons, it is impossible to supply coolant to apartments that are heated to temperatures above 95 degrees. These should include:
- The widespread use of plastic-based pipes, which are not able to function for a long time at temperatures above 100 degrees and will begin to leak after 1-2 years, will require an expensive re-equipment of the heating system
- Many houses have cast iron radiators heating, large temperature drops for which will be detrimental, significantly reducing the life span. Becoming brittle, they can break with little physical impact.
- If the pipes are heated to high temperatures, there is a high probability of getting burns when in contact with them.
If the temperature at the entrance to the house does not exceed 90 degrees, a classic collector with several balancing valves can be placed in the basement. If this figure is much higher, you will have to install an elevator heating unit, which is required to cool the coolant without pressure loss.
Read also about how to make a boiler piping with your own hands.
More about the elevator unit
If we consider the scheme of the elevator node in more detail, it will consist of the following components:
- Elevator (more often water-jet equipment is installed)
- A chamber that connects the inlet and outlet pipelines
- Nozzle
- Piping - includes nearby thermometers, control pressure gauges, shut-off and control equipment
Thus, in order to obtain the required volume of coolant entering the apartments, there is no need to send it from the boiler house through pipe lines laid in the ground. Part of the liquid can be taken on site from the return pipe.
Read also about the organization of heating in industrial premises -
The principle of operation of the elevator unit
If you look at the elevator assembly, you can see a large container that looks like a classic pot. Its additional components are various filters, which should ensure the purification of the coolant entering the heating system. The most common cleaners are:
- Mesh-magnetic filters - should clean the coolant entering directly into the house
- Dirt traps - installed in front of the elevator and remove the largest impurities
When the fluid is cleared of debris, it is redirected to the mixing chamber. Due to the high speed of movement, the hot coolant manages to pick up with it parts of the cold one, which flows through the return circuit connected to the side of the mixing chamber.
The injection process (also called liquid suction) usually occurs spontaneously. If the temperature of the liquid at the outlet of the elevator needs to be changed, it is enough to adjust the required nozzle diameter.
Thus, the elevator unit combines a mixer and a pump. However, for its functionality, there is no need to supply an electrical network.
How to regulate the coolant at the outlet
The regulation of the coolant at the outlet of the elevator can be provided by one of two methods:
- Fluid supply via smaller diameter nozzle
- Installation of manual shutters
If the coolant enters the apartments through a nozzle of a certain diameter, its speed through the pipes increases significantly. The liquid enters all risers relatively quickly, ensuring even distribution of heat throughout the house.
When plumbers decide to install metal dampers that are manually adjusted, it is extremely difficult to achieve a uniform distribution of the coolant. In case of improper regulation, apartments located on the lower floors closer to the elevator unit will be much hotter than those on the upper ones. You will have to call the master and take certain measures.
Other Features
When equipping the elevator heating unit, special attention must be paid to the ratio of the resistance of the elevator and the pressure that is created inside the supply pipe. The optimal value of this value is 1 to 7. If it is not taken into account, the operation of the entire system will be considered inefficient.
The pressure difference in the return and supply circuits has a significant effect on efficiency. An efficient system will be considered in cases where these indicators coincide. It is allowed when the coolant moves through the return pipes with a lower pressure, but not more than 0.5 kgf / cu. see If this difference is much higher, the pipeline must be cleaned, as it is likely to become clogged with dirt.
Most elevator units operate under constant conditions throughout heating period. However, adjustable equipment is considered the most effective, allowing to reduce or increase the heat supply to apartments, depending on conditions.
The main nozzle in adjustable elevators has the ability to change the outlet diameter. Foreign installations are characterized by a large range of variable values, however, in our conditions, when winters are long and cold, it is not necessary.
Adjustable elevators are most widely used in industrial or public buildings with local boiler houses. By lowering the temperature at night and on weekends, when there are no visitors and workers, it is possible to save up to 30% on heating.
Despite the numerous advantages that elevator heating units provide, several disadvantages are noted:
- Difficulty of installation
- It is necessary to calculate each of the elements of the node, otherwise their discrepancy with each other will negatively affect the efficiency
- It is necessary to ensure a minimum pressure difference in the return and direct pipelines, which does not exceed 0.5 bar
- Outlet temperature not adjustable
How to detect an elevator failure
The easiest way to make sure that the elevator unit is working properly is to compare the temperatures at the inlet and outlet of it. Possible development of events according to one scenario:
- The readings are normal - no action is needed as the equipment is operating normally
- If the figures are approximately equal, then the elevator is clogged or it is necessary to reduce the diameter of the nozzle
- If the indicators vary greatly, then the elevator is faulty and requires a more thorough inspection.
The greatest number of breakdowns is associated with the nozzle. If it is clogged, it is necessary to dismantle this element of the assembly and clean it. Over time, it is bored under the action of impurities in the fluid and requires replacement.
It is necessary to check the elevator unit for serviceability in cases where apartments on the upper floors do not receive enough heat, on the contrary, it is overabundant below. It is not recommended to eliminate any malfunctions on your own, you should contact specialists.
Before the next heating season you will have to check the elevator for operability. Particular attention is paid to the mud collector, which collects all the quarrels accumulated in the coolant. The difference in pressure at the inlet and outlet should be practically absent, otherwise we can talk about its clogging.
Summing up
In most basements of large residential and industrial buildings, the classic elevator heating unit, invented many years ago, is still installed. However, technology does not stand still.
Today, the market offers modern devices that regulate the temperature in automatic mode. They are considered more energy-efficient and economical, but their performance is impossible without being connected to the electrical network.
The heating point is the main element of the heating system, the efficiency of which largely determines the quality of hot water supply and heating of the connected object, as well as the operation of the central system. For this reason, the thermal unit, the scheme of the thermal unit must be designed for each object individually, taking into account technical features and nuances.
Purpose
The heat point is located in a separate room and is a set of elements designed to distribute heat that comes from the heating and ventilation systems, as well as hot water supply to industrial and residential premises, in accordance with the parameters and type of coolant established for them.
The thermal unit (diagram of the thermal unit below) allows not only to distribute heat among consumers, but also to take into account the costs of its consumption, as well as to ensure energy savings. It maintains comfortable conditions in the building with economical use of resources by automatically regulating the supply of heat to the heating, ventilation systems, as well as hot water supply in accordance with the established schedule, taking into account the outdoor temperature.
Standard equipment
To ensure reliable operation of a heating point, it is important that it be equipped with the following minimum set of technological equipment:
- Two plate heat exchangers (collapsible or brazed) for hot water and heating systems.
- Pumping equipment for pumping coolant to heating appliances building.
- Water treatment system.
- System for automatic control of temperature and amount of heat carrier (flow meters, controllers, sensors) to take into account the loads on heat supply, control the parameters of the heat carrier and control the flow.
- Technological equipment - regulators, instrumentation, check fittings.
It should be noted that the complete set of the thermal unit technological equipment largely depends on how heating network connected to the heating system and hot water supply.
Main systems
The substation consists of the following main systems:
- Heating system - maintains the set air temperature in the room.
- Cold water supply - provides the necessary pressure in residential premises.
- Hot water supply - designed to provide the building with hot water.
- A ventilation system that heats the air that enters the building's ventilation system.
Thermal unit: independent scheme of the thermal unit
Such a scheme is a set of equipment, divided into several nodes:
- Server and return pipeline.
- Pump equipment.
- Heat exchangers.
Depending on the type of circuit, the equipment that makes up the thermal unit will differ. The scheme of the thermal unit, developed according to an independent principle, will be equipped with a system of heat exchangers used to regulate the temperature of the circulating liquid before it is supplied to the consumer. This scheme has a number of advantages:
- Fine tune the system.
- Economical heat consumption.
- By controlling the temperature different temperature outdoor air for consumers are created more comfortable conditions.
dependent schema
This scheme for connecting a heat point is simpler. In this case, the coolant enters the consumer directly from the heating network, without any transformations.
On the one hand, this connection method does not require installation additional equipment, respectively, and cheaper. But during operation, such an installation is uneconomical, since it is not regulated at all - the temperature of the circulating liquid will always be the same as that set by the supplier of thermal energy.
Operating principle
The coolant from the boiler room through pipelines enters the heaters of the heating system and hot water supply of the apartment, after which it is sent through the return pipeline to the heating networks, and then the boiler room for reuse.
Through pumping equipment, the cold water supply system supplies water to the system where it is distributed: one part is sent to the apartments, and the other goes to the circulation circuit of the hot water supply system for subsequent heating and distribution.
Service
As mentioned above, the thermal unit consists of a large number of elements - inlet and outlet pipelines, collectors, pumps, thermostats, instrumentation and more. This is a rather complicated system, so the maintenance of thermal units should consist of the following main steps:
- Inspection of heating system elements (instrumentation, pumps, heat exchangers). If necessary, these units are replaced or repaired, as well as cleaning and flushing of heat exchangers.
- Inspection of the ventilation system (I&C shut-off valves, automatic control devices).
- Inspection of the hot water system.
- Checking the feed unit.
- Control of coolant parameters (flow rate, temperature, pressure).
- Inspection of hot water thermostats.
- Inspection of other devices that involve the installation of thermal units.
Design
Well designed project documentation is of decisive importance. The design of the heating unit can be useful in case of any technical questions from the organization supplying heat supply, as well as in case of repeated annual approvals.
After all, it is still not determined which devices will be installed, how the thermal-hydraulic regime will be regulated, where the equipment will be installed, and what the cost of installing a thermal unit at the facility will be as a result.
The principle of operation of the thermal elevator unit and the water jet elevator. In the previous article, we found out the main and features of the operation of water jet or, as they are also called, injection elevators. In short - the main purpose of the elevator is to lower the water temperature and at the same time increase the volume of pumped water during internal system heating of a residential building.
Now let's figure out how working water jet elevator and due to which it increases the pumping of the coolant through the batteries in the apartment.
The coolant enters the house with a temperature corresponding to temperature chart boiler room operation. temperature graph this is the ratio between the temperature outside and the temperature that the boiler house or CHP must supply to the heating network, and, accordingly, with small losses to your heating point (water, moving through pipes over long distances, cools down a little). The colder it is outside, the higher the temperature of the boiler room.
For example, with a temperature graph of 130/70:
- at +8 degrees outside, the heating supply pipe should be 42 degrees;
- at 0 degrees 76 degrees;
- at -22 degrees 115 degrees;
If someone is interested in more detailed figures, you can download temperature charts for various heating systems.
But let's get back to the principle and scheme of operation of our thermal elevator unit.
After passing the inlet valves, mud collectors or mesh-magnetic filters, the water enters directly into mixing elevator device - elevator, which consists of a steel body, inside which there is a mixing chamber and a constriction device (nozzle).
Superheated water exits the nozzle at high speed. As a result, a vacuum is created in the chamber behind the jet, due to which water is sucked in or injected from the return pipeline. By changing the diameter of the hole in the nozzle, it is possible, within certain limits, regulate water flow and, accordingly, the temperature of the water at the outlet of the elevator.
The elevator of the thermal unit operates simultaneously as circulation pump and as a mixer. Wherein it does not consume electricity, but uses the pressure drop in front of the elevator or, as they say, the available pressure in the heating network.
For the efficient operation of the elevator, it is necessary that available pressure in the heating network correlated with the resistance of the heating system no worse than 7 to 1.
If the resistance of the heating system of a standard five-story building is 1 m or it is 0.1 kgf / cm2, then for the normal operation of the elevator unit, the available pressure in the heating system to the ITP is at least 7 m or 0.7 kgf / cm2.
For example, if in the supply pipeline 5 kgf / cm2, then in the reverse it is not more than 4.3 kgf / cm2.
Please note that at the outlet of the elevator, the pressure in the supply pipeline is not much higher than the pressure in the return pipeline and this is normal, it is rather difficult to notice 0.1 kgf / cm2 on pressure gauges, the quality of modern pressure gauges is unfortunately at a very low level, but this is already a topic for a separate article. But if you have a pressure difference after the elevator more than 0.3 kgf / cm2, you should be wary, or your heating system is heavily clogged with dirt, or when overhaul you have greatly underestimated the diameters of the distribution pipes.
The above does not apply to battery and riser circuits, only mixing circuits using control valves and mixing pumps work with them.
By the way, the use of these regulators is also in most cases very controversial, since most domestic boiler houses use precisely high-quality temperature control. In general, the mass introduction of Danfoss automatic regulators became possible only thanks to a good marketing campaign. After all, “overheating” is a very rare phenomenon in our country, usually we all receive less heat.
Elevator with adjustable nozzle.
Now we have to disassemble how to easily control the temperature at the outlet of the elevator, and whether it is possible to save heat with the help of an elevator.
Saving heat with a water jet elevator is possible, for example, lowering the room temperature at night
, or during the day when most of us are at work. Although this issue is also controversial, we lowered the temperature, the building has cooled down, therefore, in order to warm it up again, the heat consumption against the norm must be increased.
Only one win at a cool temperature of 18-19 degrees sleep better our body feels more comfortable.
For the purpose of saving heat, a special water jet elevator with adjustable nozzle. Structurally, its execution and, most importantly, the depth of quality adjustment can be different. Typically, the mixing ratio of a water jet elevator with an adjustable nozzle varies in the range from 2 to 5. As practice has shown, such adjustment limits are quite sufficient for all occasions. Danfoss offers with a control range of up to 1 to 1000. Why is this in the heating system completely incomprehensible to us. But the price ratio in favor of a water-jet elevator with an adjustable nozzle relative to Danfoss regulators is about 1 to 3. True, we must pay tribute to the Danfoss, their products are more reliable, although not all, some varieties of inexpensive three-way valves work poorly on our water. Recommendation - you need to save wisely!
In principle, all control elevators are made in the same way. Them the device is clearly visible in the figure. , you can see an animated image of the operation of the WARS control mechanism of a water jet elevator.
And finally, a short comment - use of water jet elevators with adjustable nozzle especially effective in public and industrial buildings where it allows you to save up to 20-25% of heating costs by lowering the temperature in heated rooms at night and, especially, on weekends.
With district heating hot water, before getting into the heating radiators of apartment buildings, passes through the heating point. There it is brought to the required temperature using special equipment. For this purpose, in the vast majority of house heating points built during the Soviet era, such an element as a heating elevator was installed. This article is intended to tell what it is and what tasks it performs.
The purpose of the elevator in the heating system
The coolant leaving the boiler house or CHP has a high temperature - from 105 to 150 ° C. Naturally, it is unacceptable to supply water with such a temperature to the heating system.
Regulatory documents limit this temperature to 95 ° C and here's why:
- for safety reasons: you can get burns from touching the batteries;
- not all radiators can operate at high temperature conditions, not to mention polymer pipes.
To reduce the temperature of the network water to a normalized level allows the operation of the heating elevator. You ask - why can't you immediately send water with the required parameters to the houses? The answer lies in the plane of economic feasibility, the supply of a superheated coolant allows you to transfer a much larger amount of heat with the same volume of water. If the temperature is lowered, then it will be necessary to increase the flow rate of the coolant, and then the diameters of the heating network pipelines will increase significantly.
So, the operation of the elevator unit installed in the heating point consists in lowering the water temperature by mixing the cooled coolant from the return pipe into the supply pipeline. It should be noted that this element is considered obsolete, although it is still widely used. Now, when constructing heat points, mixing units with three-way valves or plate heat exchangers are used.
How does an elevator work?
If to speak in simple terms, then the elevator in the heating system is a water pump that does not require external energy supply. Thanks to this, and even a simple design and low cost, the element found its place in almost all heating points that were built in the Soviet era. But for its reliable operation it is necessary certain conditions, which will be discussed below.
To understand the device of the heating system elevator, you should study the diagram shown above in the figure. The unit is somewhat reminiscent of an ordinary tee and is installed on the supply pipeline, with its side outlet it joins the return line. Only through a simple tee would water from the network pass immediately to the return pipeline and directly to the heating system without lowering the temperature, which is unacceptable.
A standard elevator consists of a supply pipe (pre-chamber) with a built-in nozzle of the calculated diameter and a mixing chamber, where the cooled coolant is supplied from the return. At the outlet of the node, the branch pipe expands, forming a diffuser. The unit operates as follows:
- coolant from the network with high temperature is sent to the nozzle;
- when passing through a hole of small diameter, the flow velocity increases, due to which a rarefaction zone appears behind the nozzle;
- rarefaction causes suction of water from the return pipeline;
- the flows are mixed in the chamber and exit the heating system through a diffuser.
How the described process takes place is clearly shown by the diagram of the elevator node, where all flows are indicated in different colors:
An indispensable condition for the stable operation of the unit is that the pressure drop between the supply and return lines of the heat supply network is greater than hydraulic resistance heating system.
Along with the obvious advantages, this mixing unit has one significant drawback. The fact is that the principle of operation of the heating elevator does not allow you to control the temperature of the mixture at the outlet. After all, what is needed for this? If necessary, change the amount of superheated coolant from the network and sucked water from the return. For example, in order to lower the temperature, it is necessary to reduce the flow rate at the supply and increase the flow of coolant through the jumper. This can only be achieved by reducing the nozzle diameter, which is impossible.
Electric elevators help to solve the problem of quality regulation. In them, by means of a mechanical drive rotated by an electric motor, the diameter of the nozzle increases or decreases. This is realized by means of a cone-shaped throttling needle that enters the nozzle from the inside at a certain distance. Below is a diagram of a heating elevator with the ability to control the temperature of the mixture:
1 - nozzle; 2 - throttle needle; 3 - housing of the actuator with guides; 4 - shaft with gear drive.
Note. The drive shaft can be equipped with both a handle for manual control and an electric motor switched on remotely.
A relatively recently appeared adjustable heating elevator allows the modernization of heating points without a radical replacement of equipment. Considering how many more such nodes operate in the CIS, such units are becoming increasingly important.
Calculation of the heating elevator
It should be noted that the calculation of a water jet pump, which is an elevator, is considered rather cumbersome, we will try to present it in an accessible form. So, for the selection of the unit, two main characteristics of the elevators are important for us - the internal size of the mixing chamber and the bore diameter of the nozzle. The camera size is determined by the formula:
- dr is the desired diameter, cm;
- Gpr is the reduced amount of mixed water, t/h.
In turn, the reduced consumption is calculated as follows:
In this formula:
- τcm is the temperature of the mixture used for heating, °С;
- τ20 is the temperature of the cooled coolant in the return, °C;
- h2 - resistance of the heating system, m. Art.;
- Q is the required heat consumption, kcal/h.
To select the elevator unit of the heating system according to the size of the nozzle, it is necessary to calculate it according to the formula:
- dr is the diameter of the mixing chamber, cm;
- Gpr is the reduced consumption of mixed water, t/h;
- u is the dimensionless injection (mixing) coefficient.
The first 2 parameters are already known, it remains only to find the value of the mixing coefficient:
In this formula:
- τ1 is the temperature of the superheated coolant at the elevator inlet;
- τcm, τ20 - the same as in the previous formulas.
Note. To calculate the nozzle, it is necessary to take the coefficient u equal to 1.15u’.
Based on the results obtained, the selection of the unit is carried out according to two main characteristics. The standard sizes of elevators are indicated by numbers from 1 to 7, it is necessary to take the one that is closest to the calculated parameters.
Conclusion
Since the reconstruction of all heating points will not take place soon, the elevators will serve as mixers there for a long time to come. Therefore, knowledge of their structure and principle of operation will be useful to a certain circle of people.