Hydrostrelka: principle of operation, purpose and calculations
What is a hydraulic heater in the heating system? The hydraulic and temperature buffer, which provides the processes of correlation of supply/return temperatures and the ordered maximum flow of the coolant, is called a hydrofoil. Article on the topic: “Hydrofoil: the principle of operation, purpose and calculations” reveals the essence of the hydraulic separation of heating circuits.
Why do I need a hydraulic heater in the heating system?
It is very simple to explain why a hydraulic heating pad is needed. The processes of heat supply imbalance are familiar to owners of private houses. A modern boiler has a smaller volume circuit than the circulation flow of the consumer. The operation of the hydraulic heating system allows you to separate the hydraulic circuit of the heat generator from the secondary circuit, increase the reliability and quality of the system.
The answer to the question: “Why do I need a hydraulic heater in the heating system?” is a list of advantages of heating with a hydraulic thermal separator:
- the separator is a prerequisite for the manufacturer of equipment to guarantee maintenance for a boiler with a capacity of 50 kW or more, or a heat generator with a cast—iron heat exchanger;
- the unit provides maximum flow with laminar flow of the coolant, maintains the hydraulic and temperature balance of the heating system;
- parallel connection of the heating hydrofoil and the consumer circuit creates minimal losses of pressure, productivity and thermal energy;
- the knee arrangement of the feed-return pipes provides a temperature gradient of the secondary circuits;
- optimal selection and calculation of the hydraulic heating pad protects the boiler from the difference in supply-return temperatures, protects the equipment from heat stroke, equalizes the circulating volume of water flows in the primary and secondary circuits;
- the unit increases the efficiency of the boiler, allows the secondary circulation of a part of the coolant in the boiler circuit, saves electricity and fuel;
- the mixing keeps a constant volume of boiler water;
- in case of emergency, the separator compensates for the shortage of flow in the secondary circuit;
- the hollow separator reduces the influence of pumps with different kW power on the secondary circuits and the boiler;
- additional functions of the hydraulic separator — reduces hydraulic resistance, creates conditions for separation of dissolved gases and sludge.
The principle of operation of the hydraulic heating system allows you to stabilize the hydrodynamic processes in the system. Timely removal of mechanical impurities from the coolant will prolong the service life of pumps, valves, meters, sensors, heating devices. By separating the flows (the heat generator circuit and the independent consumer circuit), the hydrofoil ensures maximum use of the heat of combustion of fuel.
The device of the hydraulic heating system
The hydraulic separator is a vertical hollow vessel made of large diameter pipes (square profile) with elliptical plugs at the ends. The dimensions of the separator are determined by the power (kW) of the boiler, depend on the number and volume of circuits.
The heavy metal body is mounted on support posts so as not to create a line voltage on the pipeline. Compact devices are mounted to the wall, placed on brackets.
The nozzle of the hydraulic nozzle and the heating pipeline are connected using flanges or threads.
The automatic air vent valve is located at the upper point of the housing. The sediment is removed through a valve or a special valve that is embedded from below.
The material for the manufacture of the hydrofoil is low—carbon or stainless steel, copper, polypropylene. The case is treated with an anti-corrosion compound, covered with thermal insulation.
Important! Polymer models are used in a system that is heated by a boiler with a capacity of 13 to 35 kW. Hydraulic separators made of polypropylene are not used for heat generators that run on solid fuel. Making a hydraulic drill with your own hands from propylene requires experience and skills of working with professional locksmith and manual power tools.
Additional functions of hydrofoils
Advanced models combine the functions of a separator, a temperature controller and a separator. The temperature control valve provides a temperature gradient of the secondary circuits. The release of dissolved oxygen from the coolant reduces the risk of erosion of the internal surfaces of the equipment. Removal of suspended particles from the flow prolongs the service life of the impeller and bearings of circulation pumps.
The photo shows a model of a hydraulic heating pad in the section:
Horizontal perforated partitions divide the internal volume in half. The feed-back flows touch in the “zero point” zone and slide in different directions without creating additional resistance.
On top, in the high-temperature zone, there are porous vertical deaeration plates. The sludge collector and magnetic trap (magnesium anode) are located in the lower part of the housing.
Design options of the hydrofoil: pressure gauge, temperature sensor, temperature control valve and a line for powering the system at startup. Complex equipment requires adjustment, regular inspections and maintenance.
The principle of operation of a hydraulic heater in the heating system of a private house
The coolant flow passes the separator at a speed of 0.1-0.2 m/s. The boiler pump accelerates the hot water to 0.7-0.9 m/s. The recommended speed mode gives an idea of what a hydraulic heating pad is needed for.
Changing the volume and direction of movement dampens the speed of water flows with minimal loss of thermal energy in the system. Laminar flow movement leads to the fact that there is practically no hydraulic resistance inside the housing. The buffer zone separates the boiler and the consumer circuit. The pump of each of the heating circuits operates autonomously without disturbing the hydraulic balance.
Schemes of a hydraulic heater for heating (operating mode):
- Neutral mode of operation of the hydraulic separator, in which the pressure, flow rate, temperature and thermal energy of the feed —back correspond to the design parameters of the system. Pumping equipment has sufficient total capacity. The laminar flow movement in the hydrofoil ensures the processes of deaeration and deposition of suspended particles.
- The scheme reflects the principle of operation of the hydraulic heating system, in which the boiler does not have enough power to provide flow in a secondary circuit. A shortage of flow leads to a cold coolant mixture. The difference in supply/return temperatures leads to the operation of thermal sensors. Automation will bring the heat generator to the maximum gorenje mode, however, the consumer does not receive enough heat. The heating system is unbalanced, there is a threat of heat stroke.
- The volume flow of the primary circuit is greater than the flow rate of the dependent circuit coolant. An option in which the boiler operates in an optimal mode. When the unit is ignited or the pumps of the secondary circuits are switched off in parallel, the coolant circulates through the hydraulic nozzle along the primary (small) circuit. The temperature of the return, which enters the boiler, is leveled by a sub-weight from the feed. A sufficient volume of coolant is supplied to the consumer.
Prerequisite: the capacity of the circulation pump of the primary (boiler) circuit is 10% greater than the total maximum pressure of the pumps in the secondary circuit.
Methods of calculation of the hydrofoil in the heating system of a private house
How to calculate the hydraulic heating system of a private house yourself? You can calculate the required dimensions using formulas or choose the diameter according to the “3D” rule.
- The formula determines the diameter (D) according to the maximum capacity of the hydraulic separator (calculations based on the passport data for the boiler):
- The formula determines the diameter of the hydrofoil by the power of the heat generator. ΔT temperature difference of supply/return — 10°C:
- The diameter of the pipe entering the hydraulic drill or distribution manifold:
|Designation||Decryption of the symbol||Unit of measurement|
|D||The diameter of the hydrofoil housing||mm|
|P||The maximum power that the boiler has (boiler passport data)||kW|
|G||Maximum flow (throughput, flow rate) through the hydraulic separator per hour||m3/hour|
|π||Constant value (3.14)|
|ω||Maximum vertical velocity of the coolant through the separator (0.2)||m/sec|
|ΔT||Temperature difference of supply — return (boiler passport data)||°C|
|C||Water heat capacity (relative unit)||W/(kg°C)|
|V||The speed of the coolant through the secondary circuits||m/s|
|Q||Maximum consumption in the consumer circuit||m3/h|
Important! The formulas by which the calculation of the hydraulic heating pad is carried out are obtained empirically. The diameter of the inlet pipe to the hydraulic separator corresponds to the diameter of the boiler outlet.
- Determination of the parameters of the hydraulic drill by a practical method:
The approximate size for small separators is chosen according to the diameter of the inlet (outlet) pipes. The distance between the insets is at least 10 diameters of the fitting. The height of the case significantly exceeds the diameter.
The crankshaft scheme of the hydraulic heating pad is used in the selection of large-sized installations. According to the “3d rule”, the diameter of the housing is three pipe diameters. The 3d distance determines the proportions of the structure.
- The distribution of insets by the height of the separator column:
If a distribution manifold is not provided in the system, then the number of inserts into the separator is increased. The pipeline connecting the first (boiler) circuit with the hydraulic drill is distributed in height. The method allows you to adjust the temperature gradient in dynamics. The fulfillment of the condition is necessary for the qualitative selection of the coolant by secondary circuits.
Combination of a heating collector with a hydraulic heater
Small houses are heated by a boiler, which has a built-in pump. The secondary circuits are connected to the boiler through a hydrofoil. Independent contours of residential buildings with a large area (from 150 m2) are connected via a comb, the hydraulic divider will be cumbersome.
Which pipes for underfloor heating are better and more convenient to use. Technical characteristics of each type of pipe products used for underfloor heating.
The distribution manifold is mounted after the hydraulic drill. The device consists of two independent parts that unite the jumpers. According to the number of secondary contours, the pipes located in pairs are embedded.
The distribution comb facilitates the operation and repair of equipment. The shut-off and control valves of the heating system of the house are located in one place. The increased diameter of the collector ensures uniform flow between the individual circuits.
The separator and the coplanar distribution comb form a hydraulic module. The compact unit is convenient for the cramped conditions of small boiler houses.
Mounting releases are provided for strapping with an asterisk:
- the low-pressure contour of underfloor heating is connected from below;
- high—pressure radiator circuit – from above;
- the heat exchanger is located on the side, on the opposite side from the hydrofoil.
The figure shows a hydraulic drill with a collector. The manufacturing scheme provides for the installation of balancing valves between the supply/return manifolds:
The control valve provides maximum flow and pressure on the contours farthest from the hydrofoil. Balancing reduces the processes of incorrect throttling of the flow, allows you to achieve a calculated coolant supply.
Important! An autonomous heating system refers to systems operating with a high temperature of the medium under pressure (including a hydraulic heating system for a private house).
A specialist with a sufficient stock of knowledge in heating engineering, experience and work skills (electric and gas welding, plumbing, working with manual power tools) can make a hydraulic heating with his own hands. Numerous Internet sites offer step-by-step instructions for making a hydraulic heating pad, video clips will also be able to help in this process.
Theoretical knowledge will help to draw up diagrams and drawings of the hydraulic heating system, make an individual order of equipment in a specialized organization, monitor the work of the contractor. It is dangerous for life and health to trust the manufacture of responsible heating system components to non-professionals. It should be remembered that the equipment damaged by the owner’s fault is not subject to warranty repair and return.