GB2213253A - Hot air heater - Google Patents

Abstract

A hot air heater, providing a safe alternative to a Bunsen burner, e.g., for softening wax used in dentistry, comprises a hollow body (1) with a supporting base (2) and housing an electric fan (3) and electrically heated element (4) for directing hot air through an upwardly directed outlet (5) (with interchangeable nozzle (7)) around which is disposed an inlet (6) for cool air, thereby cooling the body (1). The outlet (5) is also provided with a removable guard (9) in the form of a drip tray to prevent wax dripping into the inlet (6). <IMAGE>

Description

HOT AIR HEATER This invention relates to a hot air heater in which air is blown by an electric fan past an electrically heated element to an outlet.

An object of the invention is to provide a bench top heater which is a safe alternative to a Bunsen burner in applications where a fire hazard exists, e.g., in clinical dentistry where latex gloves are worn when softening wax used in prosthetic work, the gloves being highly inflammable and on contact with a Bunsen flame being ignited instantaneously resulting in serious injury to the hands.

According to the present invention, a hot air heater comprises a hollow body with a supporting base and housing an electric fan and an electrically heated element for directing hot air through an upwardly directed outlet around which is disposed an inlet for cool air.

Thus the cool air passing downwardly through the inlet keeps the body cool, which therefore can be safely grasped by a hand, e.g., a hand in a latex glove, for movement of the heater and/or direction of the outlet other than straight up. However, the outlet is preferably provided with inter changeable nozzles, e.g., for directing the hot air sideways and/or fanning it out.

The underside of the base is preferably provided with a non-slip surface, to ensure that the heater is not accidentally moved, and the body preferably tapers upwardly from a heavy or weighted base, to afford greater stability.

The outlet may be provided with a removable guard to overlie the cool air inlet, and the guard may be in the form of a drip tray to prevent wax dripping into the inlet.

A thermal cut-out is preferably provided to protect against overheating, especially if the outlet (or a nozzle thereon) should be inadvertently covered. Although the fan and heater element may simply have a common power lead with a plug for a mains supply, a switch unit is preferably provided adjacent the base to control the fan and heater element, together or individually, which switch unit preferably incorporates an indicator light to show when at least the heater element is on, especially if the fan operates with little noise.

The heater element is preferably mounted in an openended chamber, one end of which communicates with the outlet and the other end of which receives air from the fan, and the chamber is preferably surrounded by thermal insulation leaving an annular space between itself and the inside wall of the hollow body for cool air to travel down from the inlet to the fan adjacent the base, into which projects a motor for the fan, which together with the motor, heater element and chamber may be supported as an assembly on legs upstanding from inside the base.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a hot air heater in accordance with the invention; and Figure 2 is a view partly in section from the line 2-2 of Figure 1.

The hot air heater shown in the drawings comprises a hollow body 1 with a supporting base 2 and housing an electric fan 3 and an electrically heated element 4 for directing hot air through an upwardly directed outlet 5 around which is disposed an inlet 6 for cool air. The outlet 5 is provided with interchangeable nozzles 7 (only one shown) for directing the hot air sideways and/or (as shown) for fanning it out.

The underside of the base 2 is provided with a nonslip surface 8, to ensure that the heater is not accidentally moved, and it will be seen that the body 1 tapers upwardly from what is preferably a heavy or weighted base 2, to afford greater stability. However, the body 1 can be safely and securely grasped, if need be, for movement of the heater and/or direction of the outlet 5 or nozzle 7, the cool air passing downwardly through the inlet 6 keeping the body 1 cool.

The outlet 5 is provided with a removable guard 9 overlying the cool air inlet 6, and the guard 9 is in the form of a drip tray to prevent wax dripping into the inlet 6.

A terminal cut-out (not shown) is preferably provided to protect against overheating, especially if the outlet 5 (or nozzle 7 thereon) is inadvertently covered. A switch unit IX is provided adjacent the base to control the fan 3 and heater element 4 (together or individually), which switch unit preferably incorporates an indicator light to show when at least the heater element 4 is on, especially if the fan 3 operates with little noise.

The heater element 4 is a coil element mounted on a helically grooved ceramic former 11 within an open ended annular chamber formed by an inner ceramic tube 12 and an outer mica sleeve 13, the former 11 also forming longitudinal passages for the air to be heated, and the chamber being surrounded by thermal insulation 14 enclosed within a jacket 15 extending downwards from the outlet 5, leaving an annular space 16 between the jacket and the inside wall of the hollow body 1 for cool air to travel down from the inlet 6 to the fan 3 adjacent the base 2, into which projects a motor 17 for the fan, which together with the motor, heater element and chamber is supported as an assembly on legs 18 upstanding from inside the base.

Claims (13)

1. A hot air heater comprising a hollow body with a supporting base and housing an electric fan and an electrically heated element for directing hot air through an upwardly directed outlet around which is disposed an inlet for cool air.

2. A heater as in Claim 1, wherein the outlet is provided with interchangeable nozzles.

3. A heater as in Claim 1 or Claim 2, wherein the underside of the base is provided with a non-slip surface.

4. A heater as in any one of Claims 1 to 3, wherein the body tapers upwardly from a heavy or weighted base.

5. A heater as in any one of Claims 1 to 4, wherein the outlet is provided with a removable guard to overlie the cool air inlet.

6. A heater as in Claim 5, wherein the guard is in the form of a drip tray to prevent wax dripping into the inlet.

7. A heater as in any one of Claims 1 to 6, wherein a thermal cut-out is provided to protect against overheating.

8. A heater as in any one of Claims 1 to 7, wherein a switch unit is provided adjacent the base to control the fan and heater element, together or individually.

9. A heater as in Claim 8, wherein the switch unit incorporates an indicator light to show when at least the heater element is on.

lld. A heater as in any one of Claims 1 to 9, wherein the heater element is mounted in an open-ended chamber, one end of which communicates with the outlet and the other end of which receives air from the fan.

11. A heater as in Claim 18, wherein the chamber is surrounded by thermal insulation leaving an annular space between itself and the inside wall of the hollow body for cool air to travel down from the inlet to the fan adjacent the base, into which projects a motor for the fan.

12. A heater as in Claim 18 or Claim 11, wherein the fan together with the motor, heater element and chamber is supported as an assembly on legs upstanding from inside the base.

13. A hot air heater substantially as hereinbefore described with reference to the accompanying drawings.