Water heater with anti-deformation skin

Abstract

A water heater including a tank to hold water to be heated, the tank having an outer surface, and a source of heat for heating the water in the tank. The water heater further includes a jacket surrounding the tank, the jacket having an inner surface facing the tank, a plastic skin attached to the outer surface of the tank, and an annular space between the tank and the jacket. In addition, the water heater includes foam insulation within the annular space. The foam insulation cures to form a porous solid layer of insulation between the tank and jacket, and the foam insulation shrinks during curing. The foam insulation adheres to the inner surface of the jacket, and the foam insulation does not adhere to the plastic skin during curing, to thereby reduce a deforming load on a portion of the jacket opposite the plastic skin.

What is claimed is: 
     
         1 . A water heater comprising:
 a tank to hold water to be heated, the tank having an outer surface;   a source of heat for heating the water in the tank;   a jacket surrounding the tank, the jacket having an inner surface facing the tank;   a plastic skin attached to the outer surface of the tank;   an annular space between the tank and the jacket; and   foam insulation within the annular space, the foam insulation curing to form a porous solid layer of insulation between the tank and jacket;   wherein the foam insulation shrinks during curing;   wherein the foam insulation adheres to the inner surface of the jacket;   wherein the foam insulation does not adhere to the plastic skin during curing, to thereby reduce a deforming load on a portion of the jacket opposite the plastic skin.   
     
     
         2 . The water heater of  claim 1 , wherein:
 the jacket includes a stress-enhancing feature; and   the plastic skin is applied to a portion of the tank opposite the stress-enhancing feature, but not to another portion of the tank, such that the foam insulation adheres to the outer surface of the tank except where the plastic skin is applied.   
     
     
         3 . The water heater of  claim 2 , wherein the stress-enhancing feature includes a hole in the jacket. 
     
     
         4 . The water heater of  claim 1 , wherein the source of heat for heating the water is an electrical heating element positioned within the tank. 
     
     
         5 . A method of assembling a water heater having a tank and a jacket, the method comprising:
 positioning the jacket around the tank to define an annular space therebetween;   adhering a plastic skin to a selected portion of the outer surface of the tank facing the jacket;   introducing foam insulation into the annular space;   shrinking the foam insulation in response to a reduction in ambient temperature;   adhering the foam insulation to the inner surface of the jacket and the outer surface of the tank except the selected portion of the outer surface of the tank due to the foam not adhering to the plastic skin; and   preventing the shrinking foam from applying a deforming load to a portion of the jacket that is opposite to the selected portion of the outer surface of the tank.   
     
     
         6 . The method of  claim 5 , wherein the jacket includes a stress-enhancing feature; and wherein the selected portion of the outer surface of the tank is opposite the stress-enhancing feature. 
     
     
         7 . A method of assembling first and second components, the method comprising:
 positioning the second component around the first component to define an annular space therebetween;   adhering a plastic skin to an outer surface of the first component facing the second component;   introducing foam insulation into the annular space, the foam insulation adhering to the first and second components, but not adhering to the plastic skin;   shrinking the foam insulation in response to a reduction in ambient temperature; and   separating the foam insulation from the plastic skin in response to shrinking of the foam insulation to prevent the shrinking foam from applying a deforming load to a portion of the second component that is opposite to the plastic skin attached to the first component.   
     
     
         8 . The method of  claim 7 , wherein adhering a plastic skin includes adhering tape to the outer surface of the first component. 
     
     
         9 . The method of  claim 7 , wherein the second component includes weakening features making the second component prone to deformation in response to a deforming load; and wherein adhering a plastic skin includes adhering the plastic skin on the first component opposite the weakening features. 
     
     
         10 . The method of  claim 7 , wherein separating the foam insulation from the plastic skin creates a void of trapped air adjacent the first component. 
     
     
         11 . The method of  claim 7 , wherein the first component is a water heater tank and the second component is a water heater jacket.