DE2200034A1 - RADIATOR FOR CENTRAL HEATING - Google Patents

Description

DIPL.-CHEM. JOACHIM DRESSLER PATENTANWALT 5202 HENNEF / SIEG 1 - ALLNER. TO THE VINEYARD 11

December 28, 1971 749/71 Dr / gr

Üerek Miles, Colespond Farm, West Tytherley, Near Salisbury, Wiltshire, England

"Central heating radiators"

summary

A central heating body that has a tube formed and passed through a pair of sheet metal tubes which can flow a heating or cooling liquid, wherein at least one of the sheet metal parts is shaped so that it has a greater wazid length than the length of the Radiator, wherein a plate is attached to said one sheet metal part in such a way that channels are formed through which the air can flow. Each of the sheet metal parts has a plate cooperating therewith; Both can be shaped in such a way that a zig-zag-shaped line or a line that consists of central elongated parts, which at spaced points along the radiator have laterally directed parts * The plate or plates can be slotted and there can be a Front fairing may be provided by the front

309311/0604

the sheet metal parts are kept at a distance by an intermediate piece in order to allow heat conduction Limit front fairing. A fan device can be provided to regulate the air flow through the ducts, and with this device the radiator can also be used to Air conditioning can be used in warm weather.

The invention relates to a radiator for central heating.

According to the invention, the radiator for central heating consists of two sheet metal parts that are attached to one another are attached that they form a heating line through which the heating or cooling liquid can flow, at least one of the sheet metal parts is shaped so that a wall in larger Length arises as the length of the radiator, and still having a plate on one of the said shaped sheet metal parts is attached so that between this one of the shaped sheets and dl · r Plate creates a number of channels for the passage of air.

Advantageously, both sheet metal parts are shaped in this way and one cooperating therewith on each sheet metal part Plate attached so that the radiator as with a front plate and with a back plate can be viewed provided. Each of the formed sheet metal parts can be formed in a zigzag shape be, the two sheet metal parts running parallel and at a certain distance from each other

- 3 309811/06 (H.

can and thus form a zigzag-shaped heating cable with a flattened cross-section.

The shaped sheet metal parts can also essentially lie in a vertical plane, the two plates being spaced apart and Parts of the formed sheet metal parts at certain intervals over the length of the radiator from their sides respective levels are pulled out, forming lateral extensions of the heating cable, which through the parts of the sheet metal parts which lie in the respective vertical planes mentioned are limited.

When the radiator is installed, the ducts are preferably mainly vertical. if if desired, the two shaped sheet metal parts can be formed so that the heating cable at each end has a manifold extending substantially vertically and the portion between the manifolds is divided into a number of horizontally extending flows. A supply line brings hot water to one of the vertical manifolds and via a return line the water leaves the other vertical one Manifold.

If the two formed sheet metal parts are formed in a zigzag shape, they either have an angled one or a wavy shape. If they have an angled shape, the formed sheet metal parts can have parts with which they are attached to the front and rear panels. These parts extend advantageously parallel to the front and back panels in a direction perpendicular to the direction of the channels runs.

-A- 30981 1 / O6G4

" ⁴ " 220003A

Thereby the heat transfer between the «is formed Sheet metal and the front and rear panels improved The back plate can be with (iliiiuniien or with straps be provided, by means of which the radiator can be attached to a wall.

Slots can be arranged in the front or rear panel be that allow the passage of air.

The conduit and the front and rear panels can advantageously be formed from metal, preferably made of mild steel. If it is .jedoch desired, the heating cable can also be made of a non-metallic Material, for example made of glass fiber reinforced Plastic are made to prevent corrosion.

It is advantageous to have one at the top of the heating cable and the top of the front and back panels Apertured top cover made from expanded metal, pressed steel mesh, or other material attached, which prevents household items without noticeably obstructing the flow of air fall behind or into the air ducts of the radiator. At the same time, this cover can improve the appearance of the radiator.

In the case of rubbed, heated circulation water flows in a closed circuit through an inlet valve into the vertical inlet manifold, through the heating pipe to the vertical outlet manifold and out again through an outlet valve. The warmth of the water that durrlis t.rönvt the radiator, is through the walls of the heating cable '. from <_M ^j "evenly and through con-

811 / nfifU

vection carried away from the air which the ducts through which the heating cable, the front and back plates are formed. The heat is also transferred to the front and back by conduction Back panels passed and there by convection from the air flow over the front and back panels discharged.

Since the heat output of a radiator is generally proportional to its effective surface, the heating cable of a radiator according to the invention has a significantly greater heat output than a conventional radiator of the same length and height.

Advantageously, the radiator has a front cladding that is so in relation to the walls of the heating cable it is appropriate that the heat transfer from the pipe walls to the front panel is limited during operation which means that the front cover can only reach a temperature that is significantly lower is than the temperature of the heating cable walls.

Sin radiator with such a mounted front panel is especially _t though not exclusively, for central heating systems with high temperatures, for example, systems that operate with water at a temperature of 96 C to 9i C on average, with such a high water temperatures at a given heater size, a enable increased heat dissipation. But despite this high water temperature, the outer surfaces of the radiators do not have any elevated temperatures,

309811/0604

thereby avoiding the risk of burns to persons touching the external surfaces of the radiator suffer.

To spaced the front bezel from the faceplate To hold, an intermediate piece with / rewelltem profile can be provided. The heat transfer from the front plate to your intermediate piece and thus to the front cladding can be limited «, that the intermediate piece only has contact with the front plate at a few distant points, where the sum of the contact areas is small compared to the total area of the intermediate piece.

These surfaces are preferably produced in that the intermediate piece delimited depressions receives. This allows the heat transfer from the front plate to the intermediate piece and thus to the front panel only go over the parts of the front plate and the intermediate piece that have contact with these small areas, which means that the maximum temperature that the front panel can reach can be limited.

The front fairing is advantageously made of one Piece made with the end panels and a top cover, the top cover being preferred provided with slots for the air passage is. The front panel, which advantageously consists of a smooth flat plate, is on the Intermediate piece by inductive welding of the contact points of the front cover with the corrugated Intermediate piece attached.

309811 / 0SQ4

The front cladding and / or the intermediate piece can also - if so desired - be provided with slots »

The Endverkleiduisg and the top cover preferably have inwardly bent edges at the edges which lie of dei * connection with the front panel removed ,, wherein said are provided inwardly bent edges at individual points with recesses which d n heat transfer from the back panel to limit the side panel and top cover.

Optionally, a front part also consist of a Zicksackkonstruktioii and attached to the heating tape and the front panel at various distances seira _a result of which the front panel to the outside at a distance Vora the heating cable is held., Thereby the heat transfer from the heating cable to. Limit the front panel »· s«.

The front part is preferably provided with slots «,

A blower device can be provided in order to bring about or support an air flow across the ducts. The fan is preferably a cross-flow fan or is attached to the upper end of the radiator to suck the air up through the ducts into the radiator »

The fan is advantageous through a plurality formed by blower units: which operate on a common

309811 / ÖSÖ4

seed shaft sitting with a radiator duct are connected, and are driven by an electric motor, which is preferably in or next to the center of the drive shaft. Preferably a thermostat is provided to allow operation of the electric motor and thus the blower device. The thermostat can be switched that it starts the fan when the temperature of the air sucked into the Hexzkörperkanäle drops below a certain value, or alternatively, when the temperature of the in the radiator ducts sucked air rises above a certain value, so that the radiator for heating in cold weather and can be used for air conditioning in warm weather.

The fan is preferably accommodated in a housing which is attached in a simple manner to the radiator can be attached and removed again, preferably, although not absolutely necessary, remove the apertured radiator top cover.

The invention is illustrated in examples in the following drawings. Show:

Figure 1 is an elevation of a zigzag shape Heating cable of a radiator according to the invention;

FIG. 2 the associated end view;

309811/060

Figure 3 shows the plan of a first embodiment of a radiator according to of the invention, including the zigzag heating cable, as in Figures 1 and 2, and the front, rear and side panels j

Figure 4 is a sectional view along the Line IV-IV in Figure 3 showing the formation of a number of horizontal Flow rates show j

Figure 5 shows the plan of a second embodiment of a radiator according to of the invention with the left side cut away; to the Details of the construction au show

Figure 6 is a perspective view from the front, top and one side of a Heating line, a back plate, a front plate and an intermediate piece of the radiator according to Figure 5J

FIG. 7 is a perspective view of FIG

above, the back and one end of a front panel with attached End panels and top cover for the radiator according to Figure 5}

- 10 -

309811/0604

U -

Figure 8 is a sectional view through the radiator according to Figure 5> which was created by assembling the parts shown in Figures 6 and 7;

Figure 9 is a view similar to Figure 5> the three possible forms for the line show; »

characters

10, 11 and 12 are views corresponding to Figures S, 6 and 8 of other embodiments of a heater according to the invention; FIG. 12 shows a sectional view along the line XII / XII in FIG. 10;

FIG. 13 is a front elevation, partly in section, of a radiator according to FIG of the invention provided with a fan;

Figure 14 is an end view of the heater of Figures 13 and 13

Figure 15 is a view, similar to Figure 14, of a treatise thereof.

Figures 1 to 4 show a heater consisting of the zigzag heating line 1 with a vertical one Manifold 2 at each end and a number of intermediate parts 3 »which alternate to the left and are bent to the right.

- 11 -

30981 1 / OeOA

- ii

Between each two adjacent parts 3, a part 4 extends parallel to the longitudinal axis of the radiator. The parts 4 are welded to a front panel 5 or a rear panel 6, creating channels for air flow between the
Inner surface of the front plate 5 and the outer surface of the wall 8 of the heating cable and between
the outer surface of the wall 7 of the heating cable
and the inner surface of the back plate 6 is formed
will. The line 1 is formed by parallel metal walls 7 and 8 which, as shown in FIG are.

Although not shown in the drawings,
can use the front and rear panels 5 and 6 with
Slits may be provided to allow access of the air to these channels between the duct and the front and rear panels 5 and 6 at points above the lower ends of the channels. The entry of relatively cold air at these points of the pipe effectively improves the heat transfer from the pipe walls to the air, because
this increases the temperature difference between the duct wall and the air in the upper end of the duct.

Figures 5 to 9 represent central heating radiators 20, which is particularly suitable for operation with high temperature water.

- 12 -

309811/0604

He has a zigzag-shaped heating cable 21, the is formed by spaced apart, corrugated walls 22 and 23. The wall 22 is on deformed their ends at 22a and 22b to form vertical manifolds 24 and 25 of larger cross-section than to form the remainder of the line 21. The water entering through an inlet pipe 26 thereby flows upwards through the manifold 24> which results in a more even distribution of the hot water within line 21 results as it would if the manifold 24 would not have an enlarged cross-section. This will put cold parts on the top corners of the radiator 20 avoided.

On the wall 22 and the wall 23 of the conduit 21 are a back plate 27 and a front plate 28, preferably attached by welding. The plates 27 and 28, as shown at 29, are slotted provided, the parts of the plates 27 and 28 forming the slots' being pressed so that they are beveled inward and upward, allowing air to pass through the slots in the panels 27 and 28 can flow in the direction as indicated in FIG. 8 by the arrows 30.

An intermediate piece 31 is provided with ribs 32 and on the back of the ribs the intermediate piece 31 is provided with depressions 33 (Figure 8), which are vertically spaced from each other. The intermediate piece 31 is by spot welding the tips of the recesses 33 attached to the front plate 28 at this point.

- 13 -

309811/060/4

The intermediate piece 31 is only about the Tips of the depressions with the front plate 28 in physical contact and the heat transfer by conduction from the inner front plate 28 to the intermediate piece 31 is on the heat flow limited by the walls of the depressions 33.

A front cladding 34 is designed as a flat plate which rests against the intermediate piece 31 and is attached to it preferably by inductive welding or by an adhesive. At both ends, the front cover 34 is firmly connected to an end cover 35. Each end cladding 35 has, on its edge opposite the connection with the front cladding 34, an inwardly curved edge 30 which is provided with indentations at individual points 37. As shown in Figures 5 and 8, the recesses are at the points 37 against the outside of the rear plate 27 when the front panel is in front of the intermediate member 31 34, and the edges 36 may be by spot welding the peaks of the recesses at the locations 37 be attached to the back plate 27. On its surface, the front panel 34 is firmly connected to a slotted top cover 38. On its edge opposite the connection to the front paneling 34, this upper cover 38 has a downwardly curved edge which is provided with indentations at individual points 40, at the tips of which it can be attached to the rear plate 27 by spot welding.

- 14 -

309811/0604

If hot water is supplied through the inlet 26 in the line 21 flows, the walls 22 and?. 3 the line heated by the water and through Heat conduction takes place in the heat transfer to the rear panel 27 and to the front panel 28, which take place on similar Temperature are heated, as the temperature of the water heated walls 22 and 23. As a result convection causes air to flow through the spaces

41 between the wall 23 »of the heating cable 21 and dejr Front panel 28, some of this air flowing inwards through the slots 29 in the front panel 28. Air also flows through the spaces 42 between the wall 22, the heating line 21 and the back plate 27 upwards, with some of this air passing through the slots 29 in the back plate 27 enter the space 42. The through the spaces 41 and

42 upwardly flowing air exits through the slots in the top cover 38, whereby the Slots in the top cover 38 are directed so that the air flowing through against the relevant adjacent end of the heater 20 is directed. Some of the heat is transferred from the front panel 28 to the Intermediate piece 31 passed, but the extent of this heat conduction is limited by the areas of the depressions 33> which are in contact with the front panel 28. Also through the spaces 44 between the front plate 28 and the intermediate piece 31 air flows upwards. Likewise through the spaces 45> between the ribs 32 of the intermediate piece 31 and the front cover 34, the through the spaces 44 and 45 rising air contributes to the cooling of the intermediate piece 31 and the front panel 34.

- 15 -

309811/0804

Figure 9 shows three embodiments of a line instead of the line 21 in Figures 5 to 8. The Features of the embodiment shown in Figure 9, which correspond to those in Figures 5 to 8, are with provide the same reference numbers and no more described.

The line 51 is on the left side of Figure 9 has a rear wall 52 and a front wall 53? which are shaped such that the line 51 seen from above has an H-shaped cross section, that the walls extend in a direction parallel to the parts 52a, 53a 'they run with the parts 52b _S 53b in the opposite direction apart rotate with the parts 52c, 53c again in a parallel direction but with a distance which is much greater than the distance between the parts 52a and 53a »before they with the parts 52d ₉ 53d. converge again to then extend again with the parts 52e _s 53e parallel to one another. At the ends, the walls 52, 53 are shaped in such a way that they form collecting lines 54 which have a larger cross-sectional dimension than the rest of the line 51.

On the right-hand side of FIG. 9, a line 61 is shown, which is a modification of the line 51 represents; the modification affects the middle parts 62f and 63f, which increases the cross-section of the conduit at the points where its walls diverge and come together again to run parallel and at a short distance from each other again. Portions 62f and 63f help direct the flow of water to the front and rear ends of the conduit to conduct.

- 16 -

309811 / G6G4

220003A

The embodiment shown in the middle part of FIG. 9 has a line 71, similar to the line 6l, on the right side of Figure 9, but it also has a guide surface 71g, which Extends over the full height of the radiator and which serves to direct the water to the support front and rear ends of the conduit.

FIGS. 10, 11 and 12 show a heater 80 with a conduit 81 of a shape similar to that of FIG Line 61 in Figure 9 and with a slotted back plate 82. A slotted front part 83 replaced both the front plate 28 and the intermediate piece 31 of the embodiment according to FIG. 5 to 8 and is formed in a zigzag shape with the alternately curved parts 84 and 85 of the front part 83, which are separated from one another by the parts 86 and 87, the parts 86 being parallel to the general longitudinal direction of the front part 83 and by soldering or welding with the line 8l are connected, while the parts 87 abut against the front panel 88 and, if are desired to be attached to it by soldering or welding. The front bezel 88 is preferred firmly connected to the end panels and a slotted upper part panel 89, in the same way as the front cladding 34 of the radiator 20 (above in connection with FIG 7) and attached to the backplate 82 by indentations 90 on a rim 91, as on the upper one Part of Figure 12 is shown.

- 17 -

309811/0604

Figure 12 also shows a bracket 92 for attaching the heater 80 to a wall. The carrier 92 has an upwardly directed part 93> the reaches through an opening 94 in the back plate 82nd

Figures 13 * 14 and IS show a heater 100 of the type shown by Figures 10, 11 and 12 including a fan 10I ₅ consisting of a right-angled housing 102 with an open bottom and a slotted front 103 ₉ in which a cross-flow _{fan 104 is attached or the like} As FIG. 13 shows , the fan rotor is divided into several separate sections ₉ which are mounted on a shaft 105 with bearings 106 and are driven by the electric motor 107 located in the middle.

The fan rotor 104 sucks in the air through the ducts between the heating line 8l and the front part 83 and between the heating line 8l and the back plate 82, part of the air being sucked in through the slots in the back plate 82 and in the front part 83. Air is also sucked in through the ducts between the front part 83 and the front panel 88. This air flows through the slots in the upper cladding 89 _s is sucked in axially by the fan rotor IO4, as the arrows in FIG.

-18 -

309811/0604

A thermostat 108 in the fan housing 102 is connected to a temperature sensor 109 via a capillary tube, which is attached to the lower end of the heater 100 and controls the fan motor 107. That Fan 101a II »Figure 5 is similar to the fan 101 in Figures 13 and 14 · It differs in the attachment, because the front panel 88a of the radiator to which it is attached is not connected to a top cover, thereby reducing the resistance to the flow of air to the fan 101 will.

The radiators and fans of Figures 13, 14 and 15 can all optionally be used for air conditioning by drawing chilled water through the pipe 8l is sent. So can in cold weather the thermostat 108 can be switched so that he the Fan motor 107 starts when the temperature detected by the heat sensor 109 falls below a Fixed temperature drops and in warm weather, the thermostat 108 can be switched or better to be replaced by a suitable thermostat that can be switched to run the fan motor 107 goes into operation when the temperature determined by the heat sensor 109 is above a specified Temperature increases.

The fan 101 can be fitted over the top of the radiator and fastened with screws 110 are, as Figure 14 shows, or over the upper part of a radiator its slotted upper part cladding has been removed, as shown in FIG.

- 19 -

309811 / 060A

The heat sensor is advantageously attached in a hook-shaped device 111 made of plastic, which can simply be hung into the lower slot-shaped opening of the back plate 82, as shown in Figure 15, whereby the heat sensor is brought into the desired position,

j) The fan 101 can, with appropriate modifications optionally also be attached to the lower end of the radiator and the air in the radiator ducts blow it up, but attach it to the top of the The radiator gives a better flow path for the air due to the slots in the back plate 82 and in the front part 83.

- 20 -

309811/0604

Claims (28)

- ²⁰ - 220003A Claims , j Central heating radiator, consisting of two metal sheets, which are attached to each other so that they form a heating line, through one Heating or cooling fluid can flow through it characterized in that at least one of the sheets (7, 8, 22, 23, 52, 53) is shaped so that it has a greater wall length than the length of the radiator, and that a plate (5 »6, 27, 28, 82, 83) attached to said sheet metal in this way is that a number of channels (41 or 42) between said one sheet and the Plate for the passage of air is created. 2. Radiator for central heating according to claim 1, characterized in that both sheets are shaped are and a relevant plate is provided for each of the sheets that the radiator one Front plate (5, 28, 83) and a rear plate (6, 27, 82) has. 3. Radiator for central heating according to claims 1 or 2, characterized in that each of the shaped sheets (7, 8, 22, 23) is formed zigzag, and the two sheets (7, 8, 22, 23) run parallel and at a certain distance from one another, creating a zigzag shape Heating line (1, 21) is formed by a flattened cross section. - 21 - 30981 1/0604 4. Radiator for central heating according to claim 2, characterized in that the shaped sheets (52, 53) each lie in a respective plane, the two planes being at a certain distance from one another and parts (52a, b, c, d, 53a , ed c, d) of the shaped plates (52, 53) are drawn with certain intervals along the Pleizkörper laterally from the respective planes, and lateral extensions of the line form ;, the β by the parts (52a, e _s SSa ₅₎ of the sheets be limited, those concerned in the mentioned. Layers liejnu 5. Central heating radiators after each of the Claims 1 to 4s characterized in that the Channels (41 or 42) are shaped so that they are in essentially vertical if the radiator Installed 6. Radiator for central heating according to any one of claims 1 to Ss, characterized in that the two shaped sheets (22, 23, 52, 53) are formed so that the line (21, 51) at each end a substantially vertically directed manifold (24, 25, 54) has. 7. radiator for central heating according to claim 6, characterized in that the line between the collecting lines (24, 25, 54) divided into a number of horizontally extending throughflows (10) is. - 22 - 309811/060 «22 - 8. radiator for central heating according to claim 3, characterized in that the shaped sheets (7, 8, 22, 23) have an angular shape. 9. radiator f - '. Ir central heating according to claim 3, characterized in that the shaped sheets (7, 8, 22, 23) have a corrugated shape. 10. radiator for central heating according to claim 8, characterized in that the shaped sheets (7, 8) have parts (4) to which they are attached to the front and rear panels (5 »6), respectively and which extend parallel to the front and rear panels and perpendicular to the direction of the channels, whereby the heat transfer from the formed sheets to the front and back panels is improved. 11. radiator for central heating according to claim 2, characterized in that the front plate (5, 28, 83) and / or the back plate (6, 27, 82) is or are slotted for the purpose of passage of the air. 12. Radiator for central heating according to claims 3 or 4 »characterized in that one with Apertured top cover (38, 89) is provided which extends over the top edge of the conduit (l, 21, 51, 8l) and extends the upper edges of the front and rear panels. 13. Radiator for central heating according to any one of claims 1 to 12, characterized by a - 23 - 30981 1/0604 ί £ = β dia additional front panel (34p 88) _f the of the walls of the line (51 * 71) is so arranged with respect to that is limited during operation of the heat transfer from the conduit walls to the front panel, whereby the front panel as the only assume a substantially lower temperature of the conduit walls can. 14 radiators for central heating make claim 13, characterized by an additional intermediate piece (31, # 3) with a corrugated cross-section around the front panels (34 * 88) from the line Keep your distance. 15. Central heating radiators according to claim 14p characterized in ₃ that the heat transfer from the front plate to the intermediate piece (31) and thus limited to the Frontverkleidumg (34) thereby, that for the contact between the intermediate piece and the front Platt © mat "a number of points are provided which are at a distance from one another, whereby the sum of the areas at which the intermediate piece is small compared to the total area of the intermediate piece. 16. radiator for central heating according to claim 15, characterized in that said spaced apart contact points by local recesses (33) in the intermediate piece (31) are produced. - 24 - 309811/0604 17. Radiator for central heating according to any one of claims 13 to 16, characterized in that the front cover (34, 88) with end covers (35) and a top cover (38, 89) for the radiator is firmly connected, with the top cover slotted for the passage of air is. 18. Radiator for central heating according to any one of claims 14 to 17, characterized in that the front panel (34, 88) is a flat, flat plate, which is by inductive soldering or Welding the contact points between the front panel and the intermediate piece on this intermediate piece (31, 83) is attached. 19. Radiator for central heating according to claim 14, characterized in that the front panel and / or the intermediate piece is or are slotted. 20. Central heating radiator according to claim 17, characterized in that the end panels (35) and the top cover (38, 89) at their, the connection with the front cover opposite Edges that have inwardly curved edges (36, 39, 91), said inwardly curved edges Provide the edges with indentations at individual points and the edges by means of these indentations (37, 40, 90) are attached to the back plate. 21. Radiator for central heating according to claim 13, characterized by a zigzag shape. - 25 - 309811/060 U formed the front part (83), which at certain intervals on the line (8l) and the front panel (88) is attached and thereby keeps the front panel at a distance from the line. 22. Radiator for central heating according to claim 21, characterized in that the front part (83) is slotted. 23. Central heating radiators after each of the " Claims 1 to 22, characterized by an additional fan (101, 101a) to provide an air flow through the channels to effect or support. 24. Radiator for central heating according to claim 23g, characterized in that the fan is a cross-flow fan; and that it is attached to the top of the radiator to draw air up through the ducts. 25 · Radiators for central heating systems according to claims 23 or 24, characterized in that the fan (101, 101a) consists of a number of fan units (104), which at certain intervals on a common shaft (105) are attached axially, each connected to a radiator duct and driven by an electric motor (107) seated in or near the center of the drive shaft. 26. Radiator for. Central heating according to Claim 25, characterized by an additional thermostat (IO8), the operation of the electric motor (107) and - 26 - 309811/0604 so that the fan (101, 101a) regulates. 27. Radiator for central heating according to claim 26, characterized in that the thermostat (IO8) is switched so that it starts the fan when the air sucked into the ducts has dropped to a temperature below a certain temperature. 28. Radiator for central heating according to claim 26, characterized in that the thermostat (108) is switched so that it starts the fan when the air sucked into the ducts has risen to a temperature above a certain temperature. 30981 1/0604