The present invention relates to a heating element.

Heating elements are known for application to the base of a washing machine, a dishwasher, a water heater, etc. These heating elements consist of a metal disc covered on one surface with a vitreous paste on which a thin metal layer, preferably of silver, is deposited.

A resistive track is printed on said layer by silk-screen methods, with its ends connected to terminals for connection to the mains electricity supply, and the resistive track is covered by a further layer of vitreous paste. The heating element formed in this manner is fitted to a suitable hole provided in the wall of the metal tub of the dishwasher or washing machine, the diameter of which corresponds to the diameter of the disc, with its metal surface facing the tub interior and its heating surface outwards.

However these known heating elements present certain drawbacks, and in particular:

- low efficiency due to the high loss by radiation and conduction from the resistive track facing outwards from the tub,

- the need to make a large-dimension hole in the tub walls, with possible seal leakage, - poor versatility as they can be used only on appliances provided with such a hole.

These drawbacks are eliminated according to the invention by a heating element as claimed in claim 1.

The present invention is further clarified hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a side view of a heating element according to the invention, Figure 2 is a plan view thereof, and Figure 3 is a partially enlarged section therethrough on the line Ill-Ill of Figure 1.

As can be seen from the figures, the heating element of the invention comprises a flat body 2 of rectangular plan formed from a base plate 4 of metal material, covered on one surface with a layer of vitreous paste, on which on which a layer of metal material 8, for example silver, is applied to from the conductive portions of the electric circuit.

A resistive track 10 is printed by silk-screen methods on the metal material layer 8 to complete the electric circuit.

The circuit formed in this manner is covered by a further layer of vitreous paste 12 and a cover 14 is fixed, for example by welding along three sides, to the thus formed plate 4. A standard flange 16, for example of the type for fixing traditional U or M shaped armoured resistance elements, is applied together with a seal gasket 30 to the body, so that it leaves exposed on the base plate 4 an extension 18 supporting the terminals 18 for powering by the mains electricity supply, the earthing terminal 22, and the terminal 24 connected to the NTC temperature sensors inserted into the body 2.

The terminals 22 extend into two conduits 28 which are connected to the ends of the resistive track 10.

The heating element formed in this manner is inserted into the dishwasher or washing machine through the traditional standard hole provided for armoured resistance elements, and is fixed to the tub by the flange.

It is apparent that the heating element of the present invention presents numerous advantages and in particular:

- it presents high efficiency because of the double heat transfer surface and the elimination of radiation losses, the heating element being totally immersed in water.

- it presents high versatility as it can be used as a replacement for traditional U or M shaped resistance elements,

- it can also be formed with a single heating surface as a thermally insulating layer can be inserted between the resistance element and a half-shell.