Objective: quickly organize effective heating of the premises in an electrified building, spending a minimum of funds for heating equipment. The solution is a diesel heat gun of the required power, capable of raising the temperature of the cold air of the room as soon as possible. There remains the problem of choice - before buying it is worth familiarizing yourself with the existing types of heaters, the principle of operation, the advantages and disadvantages of various models.
Three varieties of diesel fuel heaters
Burning diesel fuel for space heating has been practiced for a long time. Recall, for example, the OV-65 type air stoves installed on Ural and ZiL closed army trucks. New diesel heat generators use a similar principle, they are only made of modern materials and equipped with electronic automation.
A solar heat gun burns diesel and heats the air driven through the cylindrical combustion chamber by an axial fan. By the method of heating and flue gas emission, the products are divided into 3 groups:
- Direct heating guns emit smoke into a heated room. Accordingly, the use of such air heaters inside the home is unacceptable.
- Indirect heat generators are equipped with a side pipe for connecting the chimney and removing the combustion products to the outside.
- Infrared heating devices also pollute the air, throwing exhaust gases into the room. The difference from previous models is the increased area of the heating plate emitting radiant heat.
Reference. Among the manufacturers of heat guns, we will highlight several proven brands: Master, Aurora, Ballu, Elitech, Bison. The range of heating capacities of household units is 10 ... 30 kW, industrial models of thermal guns develop a capacity of up to 150 kW.
Consider in detail the device of each type of heaters, then analyze their pros and cons.
Direct heating principle
A gun of this type consists of the following elements:
- a cylindrical heater body and a tank with diesel fuel are attached to a metal frame (usually equipped with castors);
- a stainless steel or ceramic combustion chamber is installed in the front of the case;
- on the back of the chamber is a fuel nozzle, a glow plug and a photoelectric flame sensor;
- a plate reflecting an open flame is provided on the front side of the furnace;
- in the rear half of the case there is a fan - an air supercharger, a fuel supply system and an electronic control unit with a temperature regulator.
Note. The second function of the reflective plate is the transfer of radiant heat to objects located in the line of sight at a distance of 3-5 m.
An air-powered diesel heater is connected to the 220-volt power supply by a conventional cable and is launched literally at the touch of a button and setting the room temperature controller. How the gun works in diesel fuel:
- The user pours diesel fuel or purified kerosene into the tank, turns on the device in the network and sets the desired air temperature.
- The fan and fuel block are started, diesel fuel is fed from the tank to the nozzle, where it is mixed with air.
- The air-fuel mixture in the form of fine mist is injected into the chamber and ignited by an electric glow plug. The photocell detects the appearance of fire and after a few seconds the controller turns off the ignition electrode.
- The bulk of the air mixture pumped by the fan washes the walls of the combustion chamber from the outside, then the heated stream leaves the gun’s “barrel”.A smaller part of the air burns out with the diesel engine and is emitted in the form of exhaust gases.
- When the liquid fuel runs out or the burner goes out for other reasons, the photosensor will react and inform the control unit. The latter will stop the pump and block the flow of diesel fuel, the fan will stop working after 15-30 seconds.
- Combustion is automatically switched off when the thermostat detects the heating of the environment to the set temperature. After the room cools down, the burner will resume operation.
- Heaters of well-known brands are equipped with an overturn sensor that breaks the power supply circuit.
Clarification. If an emergency shutdown occurs, the heater will not start automatically. According to the instruction manual of the product, the user must identify and eliminate the cause of the stop, then repeat the ignition procedure.
In primitive or old models of liquid fuel guns, a manual start system with piezoelectric ignition is found. Such devices are equipped with automatic safety / overheating, but are not equipped with a temperature controller.
Indirect heaters
Diesel fan heaters of this group are arranged somewhat differently:
- the combustion chamber is completely closed, the refractory plate is hermetically sealed and is the front wall of the furnace;
- the forced air is heated only by the outer wall of the chamber, a heat exchanger and a reflective plate;
- combustion products are led out through the upper vertical pipe;
- the heat gun needs to be connected to the chimney.
Reference. In heaters, two- and three-way stainless steel heat exchangers are used. The air flow removes heat from the walls of the chamber and additional channels through which incandescent products of combustion move. Depending on the design of the heat exchanger, the smoke makes 2 or 3 strokes before going into the pipe.
The conclusion of the exhaust gases to the street allows the use of a diesel apparatus for heating enclosed spaces with insufficient ventilation. But it is still unacceptable to heat residential buildings with an indirect heating gun, the reason is the lack of a traction sensor and the corresponding automation that protects people from fumes.
Design differences infrared models
The idea of radiant heat transfer is local heating of surfaces that fall into the gun’s coverage area. The irradiated site can be in a room of any area or in the open air. It is easy to guess that in such situations it is useless to warm the air.
What is the difference between a diesel infrared gun and convective air heaters:
- a source of radiant heat is the front refractory screen;
- to expand the radiation area, the diameter of the plate and the housing are increased;
- air is supplied in small volumes sufficient to burn diesel fuel and cool the burner;
- flue gas exit - directly into the room through many small openings made in the screen.
Comparison It is believed that infrared solar heaters are more economical than convective (air). Here are the characteristics of two guns - direct-burning Ballu BHDP-30 with a power of 30 kW and a radiant heater "Master" XL 9 SR with a return of 29 kW. The diesel consumption in the first case is 2.4 kg / h, in the second - 2.3 kg / h, the difference is almost imperceptible.
The design of the infrared liquid fuel fan heater is similar to that of a similar gas gun. Both units heat surfaces instead of air and are often used to perform a variety of outdoor activities in the winter.
Fuel Features
When studying the above schemes, you probably noticed differences in the designs of the guns - in some, an air pump is depicted, in others - liquid fuel. In products of different brands, the supply of diesel fuel to the heater nozzle can be carried out in two ways:
- Electromechanical.
- Ejection.
The first option involves the use of the main nozzle and high-pressure fuel pump (TNVD), shown in the photo. The fuel supply of a diesel engine of a car is similarly arranged. The pump raises the pressure in the main line, and the nozzle injects fuel into the chamber, where it mixes with air and ignites from high temperature (in internal combustion engines - from compression).
The ejection feed of diesel fuel works like this:
- Inside the low-pressure nozzle, 2 channels converge - air and fuel.
- A rotary compressor installed in the rear of the gun pumps air into the first channel, which is why a vacuum forms in the second.
- There is an ejection effect - the vacuum begins to draw fuel from the tank through the fuel pipe.
- Once in the nozzle, the diesel fuel is mixed with the air flow and sent to the chamber, where it is successfully burned.
A remarkable fact. The rotary type compressor and the fan - supercharger of heated air are driven by one electric motor. That is, both impellers are mounted on a common shaft, the number of revolutions and performance are regulated by electronics.
The diesel fuel and the air flow sucked in by the compressor undergo coarse and fine cleaning in the respective filters. Expensive versions of heat guns are equipped with an LCD display and a diesel fuel level sensor in the tank.
Pros and cons of diesel guns
If you focus on user reviews, the main advantage of solar heaters is autonomy. An air heater is indispensable in situations where there are no other energy sources - main gas and solid fuel, or the limit on electricity consumption is very limited.
Reference. Compressors and fans of powerful models with a heating capacity of over 120 kW consume about 1000 watts of electricity. The household appliance series "wraps" a 200-300 Watt counter.
Other advantages of liquid fuel heaters:
- Mobility of the installation and efficiency of the organization of heating. Time costs are minimal - I bought a gun - brought it in place - filled in diesel fuel - turned on the heating.
- The unit is easy to move from one platform to another.
- The efficiency of the heater is quite high - manufacturers claim an efficiency of about 83%.
- Warming up speed. According to this indicator, the diesel burner outperforms the electric heating elements.
- Universality. The device is suitable for outdoor areas and any large-volume premises, except residential.
Explain an interesting point regarding efficiency. Some vendors claim the following: indirect-heating diesel guns are less efficient than direct-burning heaters that emit gases inside rooms. Like, the efficiency of these plants reaches 100%, since the heat of the combustion products is not displayed on the street.
In fact, the efficiency of different guns is about the same, but indirect heating devices really emit part of the heat along with the smoke out. Now open the documentation of any direct-burning heater and read the requirements for safe operation: for the removal of toxic gases, supply and exhaust ventilation or intensive ventilation is required.
Bottom line: direct-flow guns release all the heat into the heated room, but 20-30% of this energy is carried away by ventilation. That is, the actual losses and efficiency of both heating devices are approximately the same, although direct-flow units are cheaper than chimney models.
Disadvantages of heat generators burning diesel and kerosene:
- at a price, solar cannons lose to electric appliances - convectors and fan heaters;
- diesel is not the cheapest energy source:
- operation of the heater is accompanied by the smell of diesel fuel and exhaust gases;
- fuel of medium and low quality, sold at gas stations, quickly clogs the working parts of the heat gun with soot, and the apparatus often has to be serviced.
The choice of liquid fuel heat generator
The first step is to determine the thermal power of the device.There are nuances: the cannon can not be calculated by traditional methods, since the unit is often used to heat large volumes and rooms without proper insulation. The following methodology is proposed:
- Measure and calculate the volume of the heated room V, m³;
- Find out the temperature difference on the street and indoors in the coldest period Δt, ° С;
- Determine the dimensionless coefficient k of heat loss of the building and calculate the power of the heater Q according to the formula below.
Recommendation. Take the value of the coefficient k depending on the type and degree of thermal insulation of the building. For a metal hangar, a garage k = 4, a wooden shed - 3, a brick country house - 2 ... 2.9 (depending on the thickness of the walls). If the structure is well insulated, take a coefficient of 0.6-0.8, with an average thermal insulation - 1 ... 1.9.
Example. We calculate the thermal power of the solar gun for an insulated iron box 10 x 5 m with a ceiling height of 3 meters, the volume of the room is V = 10 x 5 x 3 = 150 m³. We take the street temperature minus 25 degrees, the internal temperature plus 10 ° С, the difference Δt = 35 ° С. How much heat will be needed: Q = 150 x 35 x 4/860 = 24.4 kW.
How to choose a gun according to operating conditions:
- For heating industrial premises, closed construction sites, hangars and warehouses, a direct heating device is suitable. If people are constantly working in the building, forced ventilation is mandatory!
- In private garages, car service stations, greenhouses, stables and other outbuildings, it is better to buy and install chimney thermal guns.
- Infrared heating devices are great for any local heating. Example: a production workshop with high ceilings or an open area where it is not possible to warm up the entire volume of air, and a limited area is quite possible.
- Use the heating system selection algorithm presented in the table:
If you need to heat a small industrial facility as a whole, pay attention to the street versions of high power guns. The installation is located outside the building, and several air ducts are laid inside for the best distribution of flows, as done above in the photo.
Maintenance and repair of heaters
During long-term operation of the gun, minor malfunctions arise, which the user can fix with his own hands. Symptoms and repair methods:
- After turning on, the device starts up, but quickly goes out. Remove the flame detector from the socket and remove soot from the working lens.
- If the heating intensity decreases, clean the air and fuel filters. The manufacturer recommends changing the filter elements at intervals of 500 hours of operation.
- Difficult or missing ignition of the air-fuel mixture. Turn out the spark plug, remove the soot and adjust the gap between the electrodes (usually 1.4 ... 1.5 mm).
- A decrease in efficiency and the appearance of black smoke indicates a clogged nozzle. In most models, the part is easily removed and cleaned, if you can not cope, call the wizard.
- Another reason for a difficult start is compressor problems. The unit must be cleaned and the working pressure adjusted; if necessary, lubricate the electric motor.
The glow plug and nozzle are located on the rear plane of the burner head. 2 tubes are connected to the atomizer (air from the compressor and fuel supply), and a high-voltage cable to the igniter. The latter often breaks into "mass", which causes the spark to disappear on the candle.
Conclusion
Infrared and convection guns in diesel fuel are convenient and powerful heat sources that can work in difficult conditions. Factory-made devices are absolutely safe, if you follow the fire precautions clearly stated in the user manual.In addition to garages and workshops, heat generators are often used at a construction site for heating plastered walls, concrete screeds and foundations, poured in winter at sub-zero temperatures.