US20190078806A1

US20190078806A1 - Handheld portable hot air device

Info

Publication number: US20190078806A1
Application number: US16/085,137
Authority: US
Inventors: Richard Looft
Original assignee: LOOFT INDUSTRIES AB
Current assignee: LOOFT INDUSTRIES AB
Priority date: 2016-03-15
Filing date: 2017-03-15
Publication date: 2019-03-14
Also published as: WO2017160215A1; SE1630056A1; EP3430314A4; CN108779917A; EP3430314A1; SE541710C2

Abstract

A handheld, portable hot air device (1, 30) comprising an electrical heating element (31), a fan (33) for inducing an air stream to pass the heating element (31) and an accumulator (34) for powering the heating element (31) and the fan (33), and in that said heating element (1, 31) comprises a ceramic tube (35) having a rear end and a front end and in which rear end a wire circuit (41, 42) with at least one heating wire (32) enters and leaves the ceramic tube (35) and in that the heating wire (32) either protrudes out from the front end of the ceramic tube (35) or enters the front end of the ceramic tube (35) in a spiral formed shape and in that one heating wire (421) is wrapped around a central ceramic conduit (43) located in the center of the ceramic tube (35).

Description

TECHNICAL FIELD

The invention relates to a handheld portable hot air device, for example an igniter suitable for ignition of a charcoal-bed of a barbeque charcoal grill or the like.

BACKGROUND OF THE INVENTION

There are plenty of different methods and devices used today for igniting a charcoal bed for a barbeque or an open fire. In general, lighter fluids have been used for this purpose for a long time. During recent years, there have been an increased interest in finding new ways of lighting a fire or igniting a charcoal grill which are more environmentally friendly. A device to be used as a charcoal igniter is described in WO 2007/008130. This device is intended to ignite a charcoal bed or the like by inducing an air stream by the use of a fan and heating the stream of air by an electric heating element which is attached to the mains by a cable.
This kind of igniter may thus replace the commonly used lighter fluids which still probably are the most common way of igniting an open fire or charcoal grill. There is a great variety of lighter fluids and they may be made from petrochemical products or from a natural, renewable sources and thus being more environmentally friendly. Regardless of the origin of the fluid used, the handling of a lighter fluid will always be a risk factor, in particular having the fluid close to an open fire or charcoal bed. In addition, there is always a risk of having unburned hydrocarbons from the lighter fuel which may influence the flavour and cause unhealthy compositions to be soaked into the food to be grilled on the glowing charcoal.
An electric igniter as described in WO 2007/008130 may thus be beneficial to use to generally replace lighter fluids. However, the use of lighter fluids may still have some advantages compared to the device described in WO 2007/008130, e.g. lighter fluids may easily be carried and used at locations where there is no access to the electric grid.
The present invention is intended to provide an igniter which may be used more easily in a wide variety of environments and locations than the one described in WO 2007/008130, e.g. when going on a hike or having a barbecue on the beach, and thus be an alternative to the use of lighter fluids which has the advantage of being able to be used at almost any location.
The document DE 102005048058 discloses an igniter powered by an accumulator giving 14-18 V which accumulator also powers a fan. The drawbacks of a device according to this document are to ignite charcoal fast enough which requires a higher temperature in the heating element than is possible with such an igniter.

OBJECT OF THE INVENTION

It is the purpose of the invention to provide a handheld hot air device for example as an igniter able to ignite for example charcoal faster than prior art igniters are able to manage.
The purpose of the invention is also to provide a handheld hot air device that can be used either as a hot air gun or a hair dryer.
The purpose of the present invention for an igniter is therefore for the heating element of the igniter to produce a higher igniting temperature than previously known igniters. Parts of the igniter are therefore capsuled by ceramics and cooled by an air stream.
The purpose of the invention is also to have a programmable device that can be set for various ranges of temperatures and air flows.

DISCLOSURE OF THE INVENTION

The present invention relates to a handheld, portable hot air device comprising an electrical heating element, a fan for inducing an air stream to pass the heating element and an accumulator for powering the heating element and the fan. The heating element comprises a ceramic tube having a rear end and a front end and in which rear end a wire circuit with at least one heating wire enters and leaves the ceramic tube and in that the heating wire either protrudes out from the front end of the ceramic tube or enters the front end of the ceramic tube, in a spiral formed shape and in that one heating wire is wrapped around a central ceramic conduit located in the center of the ceramic tube.
In an embodiment of the invention the spiral formed heating wire is long enough to pass on the outside surface the total length of the central ceramic conduit. Also a return connection of the heating wire is placed inside the central ceramic conduit.
In an embodiment of the invention the spiral formed heating wire is long enough to pass further six times outside the central ceramic conduit and inside the ceramic tube.
In an embodiment of the invention the said ceramic conduit is cylindrical.
In an embodiment of the invention the said ceramic tube comprises longitudinal inner wire compartments for enclosing said spiral formed heating wires.
In an embodiment of the invention the said ceramic tube comprises air indentations formed as grooves on the outside surface of the ceramic tube.
In an embodiment of the invention the said ceramic tube is divided into at least a front part and one or more rear parts which front part consists of thicker ceramic material than any of the rear parts.
In an embodiment of the invention the said ceramic tube basically is cylindrical formed having the central ceramic conduit mounted in the center of the ceramic tube.
In an embodiment of the invention the said ceramic tube consists of a first aluminum composition of 60% and of a second aluminum composition of 40% wherein, the first composition consists of:

- 99% aluminium oxide,
- 0.6% calcium oxid,
- 0.2% magnesium,
- 0.2% silicon oxide and wherein,

the second composition consists of:

- 65% aluminium oxide,
- 15% talc,
- 10% kaolin,
- 10% magnesium carbonate.
  The content is notated in weight percent and so is the following contents.

In an embodiment of the invention a resistant wire is attached to the electric circuit and transferring part of the voltage from the accumulator into heat used to pre-heat the air through the device.
In an embodiment of the invention electric cables are mounted between said accumulator and said fan of which cables at least one is provided with said resistant wire for reducing the voltage to the fan.
In an embodiment of the invention the material composition in the said heating wire consists of:
5% nickel,
22% chrome,
65% iron,
and 8% aluminium.
In an embodiment of the invention the said device further comprises an inlet air channel connected to the fan, said inlet air channel is arranged in the vicinity of the accumulator such that air drawn through the inlet channel provides a heat exchanging relationship with the accumulator.
In an embodiment of the invention the inlet air channel is located upstream of the accumulator to direct the air flow to be in direct contact with the accumulator.
In an embodiment of the invention the electrical components of the said device is designed to produce a temperature of the hot air at the front end of the device to be in the range of 500-800° C., preferably 650° C., to be able to use the hot air device as a handheld electrical igniter for ignition of solid fuels such as charcoal.
In an embodiment of the invention the electrical components of the said device is designed to produce a temperature of the hot air at the front end of the device to be in the range of 80-300° C., preferably 150-200° C., to be able to use the hot air device as a handheld hot air gun.
In an embodiment of the invention the electrical components of the said device is designed to produce a temperature of the hot air at the front end of the device to be either in steps or continuously selectable at a specific temperature in the range of 20-90° C. to be able to use the hot air device as a handheld hairdryer.
The invention also covers a method of manufacturing a ceramic conduit or a ceramic tube for a handheld, portable electrical hot air device according to any embodiments previous indicated, in that the method having the following steps:

- a) the materials in the ceramic composition are mixed together,
- b) the mixture is placed in a mold,
- c) the mold is treated in a kiln in a first burning at 200-300° C. for 20-40 minutes,
- d) the mold is treated in a second burning at 1500-1700° C. for 20-40 minutes.

In an embodiment of the method the following alternative step is used:

- c) the mold is treated in the kiln in a first burning at 250° C. for 30 minutes.

In an embodiment of the method the following alternative step is used:

- d) the mold is treated in a second burning at 1600° C. for 30 minutes.

The invention also covers a handheld, portable hot air device of the previous mentioned type or a hot air device as an igniter for ignition of solid fuels. The said igniter comprising an electrical heating element and a fan for inducing an air stream to pass the heating element. The said igniter also comprises an accumulator for powering the heating element and the fan, wherein it further comprises an Electronic Control Unit, ECU. The said ECU being programmed to include a Normal Ignition Cycle, NIC, in which the fan and the heating element are operating simultaneously during an Ignition Step which continues for a set time interval. Said ECU is programmed to include a Blowing Step, BS, in the Normal Ignition Cycle, NIC which follows after the Ignition Step, IS. Said Blowing step, BS, includes the feature of setting the electrical effect of the heating element to be lower than in the ignition step, IS, while the fan is still operating.
In an embodiment of the invention said ECU is programmed to control the heating element to be switched off in the blowing step.
In an embodiment of the invention the said ECU is programmed to control the fan to increase the air flow during the blowing step.
In an embodiment of the invention the said ECU is programmed to include a Preheating Step to precede the Ignition Step and the said Preheating Step including the features of setting the fan at lower speed than in the Ignition Step, e.g. completely turned off, while the heating element is turned on.
In an embodiment of the invention the said ECU is programmed to include an Energy Saving Ignition Cycle in which the energy consumed by the heating element during its Ignition Step is lower than during the Ignition Step according to the Normal Ignition Cycle.
In an embodiment of the invention the said ECU is programmed to reduce the energy consumption of the heating element during the Ignition Step in the Energy Saving Ignition Cycle by approximately 50 percent compared to the Ignition Step in the Normal Ignition Cycle by reducing the time of the Ignition Step by approximately 50 percent or reducing the power effect by the heating element in watt by approximately 50 percent.
In an embodiment of the invention the total energy consumption for an Ignition Step in an Ignition Cycle is at least 5 times more than the energy consumption during the Blowing Step for the same Ignition Cycle.
In an embodiment of the invention the said igniter further comprises an inlet air channel connected to the fan, said inlet air channel is arranged in the vicinity of the accumulator such that the air drawn through the inlet channel is in a heat exchanging relationship with the accumulator.
In an embodiment of the invention the inlet air channel is designed to direct the air flow to be in direct contact with the accumulator.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to an exemplifying embodiment thereof illustrated in the accompanying drawings, in which,

FIG. 1 illustrates a handheld portable hot air device as an igniter according to the invention;

FIG. 2 illustrates a control panel of the hot air device;

FIG. 3 illustrates a split view of a second embodiment of a portable hot air device according to the invention;

FIG. 4 illustrates a schematic circuit according to the hot air device in FIG. 4;

FIG. 5 illustrates a cross section of a first ceramic tube of the hot air device in FIG. 4;

FIG. 6 illustrates a cross section of a second and third ceramic tube of the hot air device in FIG. 4;

DESCRIPTION OF THE INVENTION

FIG. 1 is disclosed a side view of hot air device as an igniter 1 according to the invention. The igniter 1 comprises an air outlet channel 9 and an air inlet channel 6. In the outlet channel 9 is as heating element 2 located close to the outlet 9 a and a fan 3 located close to the inlet 9 a. In the inlet channel 6 is an accumulator 4 and an Electronic Control Unit (ECU) 5 located. The accumulator 4 is electrically connected to the heating element 2 and the fan 3 in order to provide electric power to these devices. The ECU 5 is connected to the heating element 2 and the fan 3 in order to control these devices, either by wires or by wireless communication. The outlet channel 9 is connected at its inlet 9 a to the outlet 6 b of the inlet channel 6. The fan 3 is arranged to draw air through inlet openings (not shown) in the inlet 6 a of the inlet channel 6 such that the air will pass the ECU 5 and accumulator 4. The air will be further guided via the fan 3 to the heating element 2 and be heated before the air will be discarded through the outlet 9 b of the outlet channel 9.
Hence, the igniter is arranged to use the intake air for cooling of the accumulator 4 and the ECU 5. There is of course the possibility the intake air actually has a temperature above the temperature of the accumulator 4 at start but as the ignition procedure starts there will be an increase temperature of the accumulator 4 from the electric discharge when powering the heating element 2 and the fan 3 as well as from the incineration process itself when the fuel bed is ignited.
The igniter 1 further comprises a handle 8 such that it may be easy to hold and a control panel 8 for setting the igniter in a desired functional mode. The control panel 8 is connected to the ECU 5 in order to provide input information for control of the heating element 2 and fan 3.
In FIG. 2 is disclosed an embodiment of a control panel 7. The control panel includes a first push button 7 a marked “N”, a second push button 7 b marked “E” and a third push button 7 c for the fan which have an associated indicator panel 7 d with light diodes which indicates “OFF”, “I” and “II”.
Push button 7 a is intended to be pressed when there is a desire to start a Normal Ignition Cycle (NIC). The letter “N” is thus intended to be short for normal. When this button is pressed could it for example be indicated by having a lamp or diode integrated in the push button 7 a such that that it is obvious the igniter now is controlled to be in the NIC mode.
When the “N” push button 7 a is pressed starts thus the NIC mode. This is the mode which should be selected for igniting a charcoal bed. Before the push button is pressed the igniter 1 is preferably located in an appropriate position in a charcoal bed (or other bed of solid fuel).
According to one embodiment is the Normal Ignition Cycle started by only activating the heating element for a short while, e.g. 5 to 15 seconds, in order to preheat the heating element 2 and surrounding material. This is called a Preheating Step (PS). Thereafter is the fan 3 activated, e.g. to be in mode I, in order to create a flow of air through the igniter 1 to be heated by the heating element 2 and blow heated air from the outlet channel 9 to the charcoal bed. This is called an Ignition step (IS). This step may be set to continue for about 30 seconds to 3 minutes, in general thought to be between 1 and 2 minutes.
After the Ignition Step (IS) is there a Blowing Step (BS). This step may continue for about 3 to 10 minutes. During this step is the effect of the heating lowered and may be completely turned off. The fan will continue to function and may even be controlled to increase its speed by selecting mode II and thus increase the amount of air blown through the igniter.
Above is thus described an embodiment of a Normal Ignition Cycle (NIC). However, the NIC may be modified in many ways, e.g. could the NIC only comprise the Ignition Step (IS). However, in general is it desired to include at least also the following Blowing Step (BS) in the NIC.
It may also be possible to have different fan speeds during the Ignition Step (IS), e.g. could the fan be set in mode I during a first part of the IS and thereafter, when there is some glow in the charcoal bed, increasing the speed of the fan during a second part of the IS to increase the ignition speed.
Hence, there are several ways of modifying the Normal Ignition Cycle depending on desired ignition properties.
The second push button 7 b, marked “E”, corresponds to an Energy Saving Ignition (ESIC). This mode is intended to ignite the charcoal bed while using less energy for ignition and thus in most instances also a slower ignition of a charcoal bed. This could for example be useful in those occasions when a user knows he will need to use the igniter 1 several times without having an opportunity to recharge the accumulator 4. It could also be an alternative to use if it is desired to speed up the ignition process for an already partly ignited bed by placing the igniter 1 in another part of the bed or to use if the bed not was properly ignited by the Normal Ignition Cycle (NIC). The ESIC is intended to reduce the power consumption by reducing the set time during which the Ignition Step (IS) is active when a lot of electric energy from the accumulator 4 is used to heat the heating element 2. Hence, this cycle is essentially programmed in the same way as the Normal Ignition Cycle (NIC) but differs in particular by reducing the energy consumption associated with the heating of the heating element in the Ignition Step (IS).
The third press button 7 c, which is positioned besides the marking “FAN”, may be pushed to select the fan to be “OFF, in mode “I” or in mode “II”. By pressing the button once will the fan 3 switch from being “OFF” to be set in mode “I” which is indicated by a lighting lamp or diode in the indicator panel 7 d next to the mark “I”. In this mode is the fan running in a slow mode. By pressing the third button once more will the fan mode change from “I” to “II” which is indicated by the indicator lamp next to “I” is turned off and the indicator lamp next to “II” starts to light. In this mode is the fan running faster than in mode “I” and the amount of air blown onto the follow bed is increased. By still another press on the push button is the fan switched off and the indicator lamp next to “OFF” is turned on and the lamp next to “II” is turned off.
To be able to manually control the operation of the fan is beneficial from the view of speeding up the ignition of a charcoal bed when already ignited. To induce an air stream is almost as efficient as inducing a heated air stream when the bed has started to glow readily. Since the electric energy consumption from powering the fan is considerably less compared to powering the heating element may this feature be desired in addition to the preprogrammed Ignition Cycles (IC).
The control panel 7 could of course include further features, e.g. still another push button for further Ignition Cycles in addition to the Normal Ignition Cycle (NIC) and Energy Saving Ignition Cycle (ESIC). There could also be a separate control for operating the heating element manually even though it is not desired to allow the heating element to be turned on for any longer time without the fan working due to the risk of overheating. The control panel 7 could of course also comprise a main switch for turning off the igniter.
The control panel need not to be located on the igniter 1 itself but could also be a remote control.
FIG. 3 discloses schematically an exploded view with the components of a second embodiment of a handheld portable hot air device 30 comprising an electrical heating element 31 having a number of heating wires 32, in the figure seven heating wires are disclosed of which six heating wires are peripheral and one is central located in the heating element 31. The hot air device includes a fan 33 driven by a motor M for inducing an air stream to pass the heating element 31. Also an accumulator 34 in the form of a battery pack for powering the heating element 31 and the fan 33 is included in the device.
The heating wires 32 are enclosed in a first ceramic tube 35 which ceramic tube abuts a rearward located second ceramic tube 36 which in turn abuts a rearward third ceramic tube 37.
In the third ceramic tube 37 a wire loop 46 is placed which has a function of reducing the voltage to the fan and at the same time add heat to the forward directed hot air stream from the fan.
For maneuvering the heat intervals and the fan speed a switch button 38 is located in the rear part of the device. A further purpose of the wire loop is to eliminate the risk of shortening the operating switch button 38.
The exploded parts in FIG. 3 is assembled into an operable device in which the switch button 38, the accumulator 34 is placed in a handle and the ceramic parts are placed in a metal housing. The front ends and the rear ends of the parts of the hot air device is indicated by the double arrow in the figure.
FIG. 4 discloses a schematic circuit 40 of the handheld portable hot air device disclosed in FIG. 3 in which the cc is formed with a first wire circuit 41 and a second wire circuit 42 in which the first wire circuit 41 consists of four spiral formed heating wires 411, 412, 413, 414 connected in series to each other. The second wire circuit 42 consists of three spiral formed heating wires 421, 422, 423 also connected in series to each other. The first wire circuit 41 and a second wire circuit 42 are attached to each other in parallel and the wire circuits are further connected to the accumulator 34 for powering the heating element 31. The total resistance R₄₁of the first wire circuit 41 is preferably 2.5Ω and the total resistance R₄₂of the second wire circuit 42 is also preferably 2.5Ω. The first heating wire 421 of the second wire circuit 42 is formed on the outside of a central ceramic conduit 43 and with a return connection 44 inside the central ceramic conduit 43, schematic illustrated in FIG. 4 with dashed lines.
For providing an air stream towards and past the heating element 31 the fan 33 driven by the motor M is attached to the accumulator 34 which fan 33 is operated by a switch 38 at a low fan power “I” in which the heating element 31 is at its maximum power and at a high fan power “II” in which the heating element 31 is at its minimum power or not powered at all. The switch 38 has also an off position “O” in which the whole device is turned off. In addition to the maximum powered heating element 31 a resistance loop 46 can be activated in the circuit in order to reduce the powering voltage and to enhance the heat capacity of the device and also to eliminate the risk of shortening of the operating power. The resistance R₄₆of the resistance loop 46 is preferably 170Ω. The wiring of the circuit 40 is connected to an eight pin, 1-8, contact 47 in turn attached to the rechargeable battery pack 34 via a programmable circuit board 48. Preferably the power of the battery pack 34 is 36V operating voltage at 2000 mAh. The programmable circuit board 48 is factory programmed and the pins of the contact 47 can be programmed to have different voltage and/or current levels in order for the device to work at its optimum. The programming is made by a computer.
FIG. 5 illustrates schematically a cross section though the first ceramic tube 35 having six wire compartments 51 in each of which one spiral formed heating wire is inserted so that the heating wires of the first wire circuit 41 are placed in adjacent wire compartments 51. Also the heating wires of the second wire circuit 42 are placed in adjacent wire compartments 52 and with one heating wire 421 placed in the center of the first ceramic tube 35 wound around the central ceramic tube 43 with its return connection 44 inside the central ceramic conduit 43. The ceramic tube 35 is provided with radially inwards extending compartment walls 53 separating each wire compartment from the adjacent wire compartment. The compartment walls 53 form an inner tube space 54 into which the central ceramic conduit 43 with its outside wound heating wire 421 is located. The first ceramic tube 35 is formed with air indentations 55 on its outside which increases the air flow from the fan to the outlet of the outlet channel of the device. As previously described the intake of air is located in order for cooling the accumulator.
FIG. 6 illustrate a cross section of the second ceramic tube 36, being identical to the third ceramic tube. The second ceramic tube 36 is approximately cylindrical in shape and provided with three identical formed air compartments 61 and a center air tube 62.

Claims

1. A handheld, portable hot air device comprising an electrical heating element, a fan for inducing an air stream to pass the heating element and an accumulator for powering the heating element and the fan, wherein said heating element comprises a ceramic tube having a rear end and a front end, wherein a wire circuit with at least one heating wire enters and leaves the ceramic tube at the rear end, wherein the heating wire either protrudes out from the front end of the ceramic tube or enters the front end of the ceramic tube in a spiral formed shape and wherein a spiral formed heating wire is wrapped around a central ceramic conduit located in a center of the ceramic tube.

2. The hot air device of claim 1, wherein the spiral formed heating wire is long enough to pass on an outside surface for a total length of the central ceramic conduit and wherein a return connection is placed inside the central ceramic conduit.

3. The hot air device of claim 2, wherein the spiral formed heating wire is long enough to pass further six times outside the central ceramic conduit and inside the ceramic tube.

4. The hot air device of claim 1, wherein said central ceramic conduit is cylindrical.

5. The hot air device of claim 1, wherein said ceramic tube comprises longitudinal inner wire compartments enclosing said spiral formed heating wire.

6. The hot air device of claim 1, wherein said ceramic tube comprises air indentations formed as grooves on an outside surface of the ceramic tube.

7. The hot air device of claim 1, wherein said ceramic tube is divided into at least a front part and one or more rear parts wherein the front part consists of thicker ceramic material than the one or more rear parts.

8. The hot air device of claim 1, wherein said ceramic tube is substantially cylindrical and wherein the central ceramic conduit is mounted at a center of the ceramic tube.

9. The hot air device of claim 1, wherein said ceramic tube consists of a first aluminum composition of 60% and of a second aluminum composition of 40% wherein,

the first composition consists of:

99% aluminium oxide,

0.6% calcium oxide,

0.2% magnesium,

0.2% silicon oxide and wherein,

the second composition consists of:

65% aluminium oxide,

15% talc,

10% kaolin,

10% magnesium carbonate.

10. The hot air device of claim 1, wherein a resistant wire is attached to the electric heating element and transfers a part of a voltage from the accumulator into heat used to pre-heat air through the device.

11. The hot air device of claim 10, wherein electric cables are mounted between said accumulator and said fan wherein at least one of the cables is provided with said resistant wire for reducing the voltage to the fan.

12. The hot air device of claim 1, wherein the material composition of said heating wire consists of:

5% nickel,

22% chrome,

65% iron, and

8% aluminium.

13. The hot air device of claim 1, comprising an inlet air channel connected to the fan, wherein said inlet air channel is arranged in a vicinity of the accumulator such that air drawn through the inlet channel provides a heat exchanging relationship with the accumulator.

14. The hot air device of claim 13, wherein the inlet air channel is located upstream of the accumulator to direct the air to be in direct contact with the accumulator.

15. The hot air device of claim 1, wherein electrical components of the said device are configured to produce a temperature of hot air at the front end of the device to be in a range of 500-800° C., such that the hot air device is configured as a handheld electrical igniter for ignition of solid fuels such as charcoal.

16. The hot air device of claim 1, wherein electrical components of the said device are configured to produce a temperature of hot air at the front end of the device to be in the range of 80-300° C., such that the hot air device is configured as a handheld hot air gun.

17. The hot of claim 1, wherein electrical components of the said device are configured to produce a temperature of hot air at the front end of the device to be either in steps or continuously selectable at a specific temperature in the range of 20-90° C. such that the hot air device is configured as a handheld hairdryer.

18. A method of manufacturing a ceramic conduit or a ceramic tube for a handheld, portable electrical hot air device, comprising:

a) mixing the materials in the ceramic composition together,

b) placing the mixture in a mold,

c) treating the mold in a kiln in a first burning at 200-300° C. for 20-40 minutes, and

d) treating the mold is in a second burning at 1500-1700° C. for 20-40 minutes;

wherein the hot air device comprises an electrical heating element and a fan for inducing an air stream to pass the heating element, wherein said heating element comprises the ceramic tube, the ceramic conduit located in a center of the ceramic tube, and a spiral formed heating wire wrapped around the ceramic conduit.

19. The method of claim 18, wherein treating the mold in a kiln in a first burning at 200-300° C. for 20-40 minutes comprises treating the mold in the kiln in the first burning at 250° C. for 30 minutes.

20. The method of claim 18, wherein treating the mold in the second burning at 1500-1700° C. for 20-40 minutes comprises treating the mold in the second burning at 1600° C. for 30 minutes.

21. A hot air device, comprising:

an electrical heating element and a fan for inducing an air stream to pass the heating element,

an accumulator for powering the heating element and the fan, and

an Electronic Control Unit (ECU),

wherein said ECU is configured to provide a Normal Ignition Cycle in which the fan and the heating element are operating simultaneously during an Ignition Step which continues for a set time interval, and a Blowing Step in the Normal Ignition Cycle which follows after the Ignition Step, and

wherein said Blowing step includes setting an electrical effect of the heating element to be lower than in the ignition step while the fan is still operating.

22. The hot air device of claim 21, wherein said ECU is configured to control the heating element to be switched off in the blowing step.

23. The hot air device of claim 21, wherein said ECU is configured to control the fan to increase air flow during the blowing step.

24. The hot air device of claim 21, wherein said ECU is configured to provide a Preheating Step preceding the Ignition Step, said Preheating Step including setting the fan at lower speed than in the Ignition Step or turning the fan off while the heating element is turned on.

25. The hot air device of claim 21, wherein said ECU is configured to include an Energy Saving Ignition Cycle in which energy consumed by the heating element during an Ignition Step of the Energy Saving Ignition Cycle is lower than during the Ignition Step of the Normal Ignition Cycle.

26. The hot air device of claim 25, wherein said ECU is configured to reduce the energy consumption of the heating element during the Ignition Step of the Energy Saving Ignition Cycle by approximately 50 percent compared to the Ignition Step of the Normal Ignition Cycle by reducing the time of the Ignition Step by approximately 50 percent or reducing a power effect by the heating element in watt by approximately 50 percent.

27. The hot air device of claim 21 wherein a total energy consumption for the Ignition Step is at least 5 times more than an energy consumption during the Blowing Step.

28. The hot air device of claim 21, comprising an inlet air channel connected to the fan, wherein said inlet air channel is arranged in a vicinity of the accumulator such that air drawn through the inlet channel is in a heat exchanging relationship with the accumulator.

29. The hot air device of claim 28, wherein the inlet air channel is configured to direct the air to be in direct contact with the accumulator.