Among the many types of household heaters, vapor-drop type heating devices are deservedly popular — units of a simple principle of operation with an affordable price range.
In order to take into account the possibility of acquiring this device — compact, efficient, reliable, when choosing a device for heating housing, we will consider vapor-drop heaters in more detail.
The device and principle of operation of vapor-drop type heaters
This type of heater belongs to the group of “electric convectors”, that is, to heaters, the operation of which initiates convective air flows in the heated room — the air in contact with the unit body heats up and rises, being replaced by a colder one.
The basis of the design of vapor-drop type heaters is a needle-type heating element. The tubular heater is mounted in the lower part of a sealed cast-iron, steel or aluminum tank with water, ethanol or methanol, filled above the level of the heating element, the needle-shaped design of which does not require a large amount of liquid for this.
The container in the PKN case is installed at an angle — the deviation of the plane of its base from the horizontal is approximately 20 degrees.
When the device is connected to the network, the water is heated by the heating element to the boiling point for several minutes and begins to evaporate, filling the free volume of the tank with steam.
Hot steam under pressure, in contact with the metal walls in the upper part of the tank, condenses on them with the release of thermal energy. Due to the high thermal conductivity of the metal, heat is transferred to the air layers closest to the heater, initiating convection in the room, and the condensate in the tank flows down the inclined walls to its lower part and, heated up again by the heating element, evaporates again.
Thus, two coolants are involved in the heat transfer process — water and steam, but the liquid temperature does not exceed 100 degrees, and the steam in the tank can heat up to 120, so the upper part of the PKN is always hot during operation.
To increase the intensity of heat transfer in most PKN models, the upper part of the reservoir with liquid is made in the form of multi-section blocks of narrow sections with additional external fins, which significantly increases the heat transfer area.
Important! The volume of the reservoir of a vapor-drop heater, free from liquid, is filled with a technical vacuum, therefore, the transition of the coolant from a liquid state to a vapor during heating occurs bypassing the boiling process, that is, silently.
Technical characteristics and types of steam condensate heaters
The main criterion for choosing a PKN is the power required to heat a room of a specific area and volume. For household models of vapor-drip heaters, this parameter is in the range from 0.5 to 2.0 kW. Accordingly, in regions with a temperate climate, in the presence of effective external insulation of building envelopes, a PKN with a power of 1.5 kW will provide heating for a room up to 15 sq. m.
The design of various models of vapor-drop heaters requires an accurate calculation of the ratio of the power of the needle heating element, the surface area of the unit body, taking into account the fins and the amount of coolant used in the tank.
The maximum PKN power of 2 kW is chosen for safety reasons. With reference to this value, the volume of the tank, the amount of liquid poured into it and the heat transfer area are calculated. The ratio of these parameters should ensure effective vaporization in the tank at a safe steam pressure (not more than 0.07 MPa), the surface temperature of the body is not more than 115 degrees, and the location of the needle heating element is always below the liquid level — even when the heater is operating in the maximum normal mode.
Important! A correctly performed calculation of the ratios of the power of the heating element, the amount of coolant, the volume of the reservoir and the heat transfer area of the body allows not to equip the PKN with an overpressure relief valve. At the same time, for safety reasons, devices with a power of more than 1.5 kW are produced with increased strength characteristics and are intended mainly for industrial premises.
Vapor-drop type heaters, as mentioned above, are divided into household appliances and units for industrial use.
Devices for industrial use are more powerful, respectively, and their dimensions are larger. With the release of such units, the aesthetics of execution are relegated to the background, giving way to work efficiency, the strength of the case and the security of the control system, as well as the supply cable.
However, even industrial vapor-drop heaters of modern models have a class of exterior finish above average, which allows them to be used in everyday life without prejudice to the interior of the room.
Modern PKN heaters, both for domestic and industrial purposes, are equipped with a security system (automatic shutdown when the bimetallic plate is overturned or overheated) and temperature control — a thermostat that operates on the basis of data from a temperature sensor, standard or additionally installed by hand in the actual area of the room — according to reaching the set temperature in this zone, the heater will turn off.
PKN models by location are divided into floor, wall and universal. The principle of operation of devices of all these designs is the same, the heat transfer by the units is carried out by both sides of the panel.
Floor-standing units are equipped with support legs that provide it with a stable position on a horizontal plane, or a platform with wheels that facilitate movement.
Important! If the unit has a permanent location, but there is a fear of tipping over, then after dismantling the wheels, the supports can be fixed on the floor using self-tapping screws.
In the event of an unforeseen overturning of the heater, the automatic disconnection of the network will work, and the relatively low temperature of the housing will not be able to cause a fire.
Wall-mounted models have holes on one side of the panel for brackets that attach the unit to the wall. The design and size of the brackets ensure the location of the PKN at a distance of 7–10 cm from the supporting base, which reduces the thermal effect of the heater on the wall and does not prevent air convection from the back of the device. The section of the wall located behind the installed heater must be additionally equipped with heat protection made of heat-resistant material.
The design of the universal location PKN allows you to install support legs on them or mount them on the wall. The effectiveness of one or another method of application depends on the specific operating conditions.
Application of PKN
The production of steam condensate heaters for both domestic and industrial needs is based on the possibility of their use for a variety of purposes:
- heating of urban and suburban buildings for residential, public and industrial purposes;
- in the northern regions — heating of rooms remote from the main heating means installed in the house;
- maintenance in the basement floors and basements of the temperature necessary for the normal functioning of the water supply and fan system in the winter;
- an alternative method of heating housing during emergency repairs of the main heating systems;
- heating of housing that is inappropriate for equipment with a heating circuit due to significant heat losses associated with a large length of pipe spans;
- maintaining the required temperature regime in the premises when performing work there that requires it technologically.
In fact, the scope of steam condensate heaters is much wider, so the high degree of demand for PKN can be said with confidence.
Advantages and disadvantages of vapor-drop design heaters
Assessing the feasibility of using a steam-condensate type heater under certain conditions, you need to know the main pros and cons of these units.
Advantages of PKN:
- environmental friendliness — the absence of any emissions into the heated space,
- safety — a fairly low case temperature (they do not affect the humidity in the room and do not burn dust), equipped with an automatic shutdown system in case of overheating, noiselessness;
- a sufficient degree of automation of control of most models;
- durability — due to the lack of air in the tank, which is necessary for corrosion, but is limited by the life of the heating element;
- frost resistance — the expansion of the coolant during freezing will not cause the destruction of the tank due to the presence of free volume in it;
- compactness, possibility of wall installation;
- technological efficiency — ease of installation and daily maintenance, no need for a chimney.
Disadvantages of vapor-drop heaters:
- rather high cost of units, even for domestic purposes;
- inherent in all electric heaters increased power consumption;
- the impossibility of repairing heaters in domestic conditions in cases associated with depressurization — an error in the amount of coolant is fraught with an explosion when heated.
Self-manufacturing of PKN
The high cost of steam condensate heaters, with the seeming simplicity of the principle of operation, gives rise to the temptation to manufacture such a unit on their own, given the modern availability of materials, components and tools.
Indeed, today vapor drop heaters often made with your own hands — materials and components for their assembly can be easily found on sale. But it is not realistic to produce such units at home only after reading the instructions and recommendations — there are a lot of designs of such devices, and the manufacturing technology of each has individual characteristics. At the same time, it is necessary to have not only general assembly and welding skills, but also practical experience specifically in the manufacture of PCN.
In addition, the assembly of a low-power vapor-drop heater is impractical — there are many other types of inexpensive heating devices, moreover, industrial-made ones that can cope with home heating better and safer. And a home-made high-performance unit is not so aesthetic as to be used to heat a home.
The heating register shown above, operating on a vapor-drop type, can serve as a visual aid to the question of how to make a PKN yourself
The unit is assembled from four fragments — “streams” made of a steel pipe with a diameter of 50 mm and plug-plates made of sheet steel. A heating element is mounted in the lower “stream”, equipped with a branch pipe. In the upper part of the register there is a plug with a valve through which a mixture of water and antifreeze was poured into the radiator and air was bled under pressure when the device was first turned on.
A coolant is poured into the lower “stream”, which evaporates when heated. Steam fills all the free space of the “streams”, gives off heat to the walls of the radiator and condenses on them, then flowing back down to the heating element.
The design of the PKN may be simpler, but this does not eliminate the need for specific professional skills.
Important! The lack of vacuum in a homemade radiator causes the coolant to boil, accompanied by a certain noise during operation of the unit.
Steam heaters are efficient electric heaters. Their effectiveness explains the demand for these devices, which, in turn, affects the pricing policy — the cost of PKN is higher than the prices of many other infrared heaters. However, striving for the efficiency of the heating method, one should not forget about a more important factor — the safety of the equipment, which cannot be fully ensured in the handicraft production of units.
The main essence of the article
- Vapor-drop heating devices are modern reliable units, the simplicity of the design of which is their advantage, and not a flaw.
- When choosing a method of heating a home, one should not ignore PKN — effective heaters, knowledge of the characteristics of which will simplify their use. The use of vapor-drop heaters in everyday life and at work is proof of their effectiveness.
- When planning the use of PKN, it is necessary to know their technical characteristics, types of instrument execution and selection criteria for these units.
- Self-manufacturing of drip-steam electric heaters is possible, but is associated with the risk of accidents during the operation of such equipment in case of a design error.