Antisweat heater structure

Claim 2

In a refrigeration apparatus cabinet structure having housing walls defining a refrigerated space opening outwardly through an access opening, and a mullion wall extending across said space between said portions of said housing walls, the improvement comprising: heating means in said cabinet structure for heating said walls to prevent sweating thereon, said heating means being constructed and arranged to provide differential heating of different portions of the walls effectively correspondingly to the tendency for sweating to occur thereon as an incident of the refrigeration of said space, said heating means comprising an elongated resistance heater in at least one of said walls for providing heat therein adjacent said access opening, said resistance heater having a first portion having a first preselected value of electrical resistance per unit length of said heater adjacent juxtaposed portions of said housing and mullion walls, and a second portion connected in series with said first portion and having a second, lower preselected value of electrical resistance per unit length of said heater spaced therefrom, whereby electrical current passed in series through said portions causes a preselected differentially greater heating effect at said juxtaposed wall portions.

Claim 3

The refrigeration apparatus cabinet structure of claim 1 wherein a said resistance heater is provided one each in said housing and mullion walls.

Claim 4

The refrigeration apparatus cabinet structure of claim 1 wherein said resistance heater is disposed in said mullion wall and provided with a portion having said first preselected value of resistance per unit length of said heater at each portion juxtaposed to said spaced portions of the housing walls.

Claim 5

The refrigeration apparatus cabinet structure of claim 1 wherein said resistance heater is disposed in said housing walls and is provided with a portion having said first preselected value of resistance per unit length of said heater at each portion juxtaposed to said mullion wall.

Claim 6

The refrigeration apparatus cabinet structure of claim 1 wherein said first and second values of resistance per unit length of said heater are preselected to cause approximately one-third of the heating effect of the heater to be produced by said first portion.

Claim 7

The refrigeration apparatus cabinet structure of claim 1 wherein said resistance heater defines opposite end portions, each defining a said first portion and having said first preselected value of resistance per unit length of said heater, the first and second values being preselected to cause approximately one-third of the heating effect of the heater to be produced by each said end portion.

Claim 8

The refrigeration apparatus cabinet structure of claim 1 wherein said second value of resistance per unit length of said heater is preselected to develop approximately 1.3 watts of heat energy along said second portion.

Claim 9

The refrigeration apparatus cabinet structure of claim 1 wherein said heating means further comprises connecting means for connecting said heater portions in electrical series.

Claim 10

The refrigeration apparatus cabinet structure of claim 8 wherein said connecting means comprises tubular means for connecting said heater portions in end-to-end electrically connected association.

Claim 11

In a refrigeration apparatus cabinet structure having housing walls defining a refrigerated space opening outwardly through an access opening, and a mullion wall extending across said space between said portions of said housing walls, the improvement comprising: a first resistance heater in said housing walls for providing heat therein adjacent said access opening, a second resistance heater in said mullion wall for providing heat therein adjacent said access opening, each said resistance heater having a first portion having a first preselected value of resistance per unit length of said heater adjacent juxtaposed portions of said housing and mullion walls, and a second portion connected in series with said first portion having a second, lower preselected value of resistance per unit length of said heater spaced therefrom, whereby electrical current passed in series through said portions causes a differentially greater heating effect at the juxtaposed wall portions corresponding to the tendency for seating to occur thereon as an incident of the refrigeration of said space.

Claim 12

In a refrigeration apparatus cabinet structure having housing walls defining a refrigerated space opening outwardly through an access opening, and a mullion wall extending across said space between said portions of said housing walls, the improvement comprising: a first resistance heater in said housing walls for providing heat therein adjacent said access opening, a second resistance heater in said mullion wall for providing heat therein adjacent said access opening, each said resistance heater having a first portion having a first preselected value of resistance per unit length of said heater adjacent juxtaposed portions of said housing and mullion walls, and a second portion connected in series with said first portion having a second, lower preselected value of resistance per unit length of said heater spaced therefrom, whereby electrical current passed in series through said portions causes a differentially greater heating effect at the juxtaposed wall portions corresponding to the tendency for seating to occur thereon as an incident of the refrigeration of said space.

Claim 13

The cabinet structure of claim 10 wherein each of said resistance heaters comprises a pair of parallel cables with said first portion defining a looped return at one end of said second portion.

Claim 14

The cabinet structure of claim 10 wherein said heater portions comprise separate heater cables, and connector means are provided for serially connecting said separate heater cables.

Claim 15

In a refrigeration apparatus cabinet structure having housing walls defining a refrigerated space opening outwardly through an access opening, and a mullion wall extending across said space between spaced portions of said housing walls, the improvement comprising: heating means in said cabinet structure for heating the walls to prevent sweating thereon, said heating means being constructed and arranged to provide differential heating of different portions of said walls effectively corresponding to the tendency for sweating to occur thereon an an incident of the refrigeration of said space, said heating means comprising a resistance heater in at least one of said walls for providing heat therein adjacent said access opening, said resistance heater comprising a first heater cable adjacent a first juxtaposed portion of said housing and mullion walls, a second heater cable between said first juxtaposed portion and a spaced second juxtaposed portion of said housing and mullion walls, a third heater cable adjacent said second juxtaposed portion and a fourth heater cable between said first and second juxtaposed portions, said first heater cable having a first preselected value of resistance per unit length of cable, a first end for connection to a first terminal of source of electrical power and a second end, said second heater cable having a second preselected value of resistance per unit length of cable lower than said first preselected value, a first end connected to said first heater second end and a second end, said third heater cable having a third preselected value of resistance per unit length of cable greater than said second preselected value, a first end connected to said second heater second end and a second end, said fourth heater cable having a fourth preselected value of resistance per unit length of cable lower than said first and third preselected values, a first end connected to said third heater second end and a second end for connection to a second terminal of said source of electrical power.

Claim 16

In a refrigeration apparatus cabinet structure having housing walls defining a refrigerated space opening outwardly through an access opening, and a mullion wall extending across said space between spaced portions of said housing walls, the improvement comprising: heating means in said cabinet structure for heating the walls to prevent sweating thereon, said heating means being constructed and arranged to provide differential heating of different portions of said walls effectively corresponding to the tendency for sweating to occur thereon an an incident of the refrigeration of said space, said heating means comprising a resistance heater in at least one of said walls for providing heat therein adjacent said access opening, said resistance heater comprising a first heater cable adjacent a first juxtaposed portion of said housing and mullion walls, a second heater cable between said first juxtaposed portion and a spaced second juxtaposed portion of said housing and mullion walls, a third heater cable adjacent said second juxtaposed portion and a fourth heater cable between said first and second juxtaposed portions, said first heater cable having a first preselected value of resistance per unit length of cable, a first end for connection to a first terminal of source of electrical power and a second end, said second heater cable having a second preselected value of resistance per unit length of cable lower than said first preselected value, a first end connected to said first heater second end and a second end, said third heater cable having a third preselected value of resistance per unit length of cable greater than said second preselected value, a first end connected to said second heater second end and a second end, said fourth heater cable having a fourth preselected value of resistance per unit length of cable lower than said first and third preselected values, a first end connected to said third heater second end and a second end for connection to a second terminal of said source of electrical power.

Claim 17

The refrigeration apparatus cabinet structure of claim 13 wherein said resistance heater is provided in said housing walls.

Claim 18

The refrigeration apparatus cabinet structure of claim 13 wherein said resistance heater is provided in said mullion wall.

Claim 19

The refrigeration apparatus cabinet structure of claim 13 wherein one said resistance heater is provided in said housing walls and one said resistance heater is provided in said mullion wall.

Claim 20

The refrigeration apparatus cabinet structure of claim 13 wherein said first preselected value and said third preselected value are each greater than or equal to three times said second preselected value and said fourth preselected value.

Claim 21

In a refrigeration apparatus cabinet structure having housing walls defining a refrigerated space opening outwardly through an access opening, and a mullion wall extending across said space between said portions of said housing walls, the improvement comprising: a generally rectangular outwardly facing surface in said mullion wall spanning essentially the full width of said mullion wall, a resistance heater on said surface and comprising a first heater cable having a first preselected value of resistance per unit length of said heater and located at one end of said surface, a second heater cable having a second preselected value of resistance per unit length of heater electrically series-connected with said first heater cable and extending to the opposite end of said surface, a third heater cable having a third preselected value of resistance per unit length of said heater electrically series-connected with said second cable and disposed at said opposite end of said surface, and a fourth heater cable having a fourth preselected value of resistance per unit length of said heater electrically series-connected with said third cable and extending to said one end of said surface wherein said first and said third heater cables are looped transverse to the direction of said surface and said preselected values are chosen to concentrate approximately one-third of the heat produced by said resistance heater at said one end of said surface and approximately one-third of said heat at said other end of said surface, cover means substantially coextensive with said surface and in heat transfer association with said resistance heater for transmitting outwardly the heat produced by said resistance heater, an electrical connector connected to said first cable and said fourth cable for providing connection with a source of electrical power, whereby said resistance heater will provide differential heating of different portions of said walls effectively corresponding to the tendency for sweating to occur thereon.

Claim 22

In a refrigeration apparatus cabinet structure having housing walls defining a refrigerated space opening outwardly through an access opening, and a mullion wall extending across said space between said portions of said housing walls, the improvement comprising: a generally rectangular outwardly facing surface in said mullion wall spanning essentially the full width of said mullion wall, a resistance heater on said surface and comprising a first heater cable having a first preselected value of resistance per unit length of said heater and located at one end of said surface, a second heater cable having a second preselected value of resistance per unit length of heater electrically series-connected with said first heater cable and extending to the opposite end of said surface, a third heater cable having a third preselected value of resistance per unit length of said heater electrically series-connected with said second cable and disposed at said opposite end of said surface, and a fourth heater cable having a fourth preselected value of resistance per unit length of said heater electrically series-connected with said third cable and extending to said one end of said surface wherein said first and said third heater cables are looped transverse to the direction of said surface and said preselected values are chosen to concentrate approximately one-third of the heat produced by said resistance heater at said one end of said surface and approximately one-third of said heat at said other end of said surface, cover means substantially coextensive with said surface and in heat transfer association with said resistance heater for transmitting outwardly the heat produced by said resistance heater, an electrical connector connected to said first cable and said fourth cable for providing connection with a source of electrical power, whereby said resistance heater will provide differential heating of different portions of said walls effectively corresponding to the tendency for sweating to occur thereon.

Claim 23

The refrigeration apparatus cabinet structure of claim 18 wherein said second and fourth heater cables comprise a pair of parallel cables, and said third cable is connected between ends of said pair to form a looped return.

Claim 24

The refrigeration apparatus cabinet structure of claim 18 wherein said second and fourth heater cable comprise a pair of parallel cables, and said third cable is connected between adjacent ends of said pair to form a looped return.

Claim 25

The refrigeration apparatus cabinet structure of claim 18 wherein channel means are provided for receiving and retaining said cables in thermal transfer association with said cabinet mullion wall surface.