Method for manufacturing a composite foamed water-heater body from a foamed fiber-reinforced polyester resin and the resultant product

Method of fabricating a plastic water heater body which has no metallic walls, either on the outside or on the inside, which comprises:

• (1) providing a plastic shell having at least one orifice therein which forms the interior of the water heater body and also serves as an interior molding wall,
• (2) providing a mold having an opening therein and consisting of at least two parts, placing said shell inside said mold and providing a space between the outside of the shell and the inside of said mold, said shell and at least one part of the mold having cooperating means for centering and holding the shell inside the mold,
• (3) introducing a liquid into the inside of said shell through the orifice therein,
• (4) casting a liquid mixture consisting essentially of a polyester resin composition capable of foaming and polymerizing in said mold through the opening therein, controlling the temperature of the expanding and polymerizing resin during casting so that it does not exceed about 40.degree. C. by cooling the outside of the mold to a temperature of from about 10.degree. C. to about 15 .degree. C. so as to obtain a skin effect on the surface of the cast resin in contact with the mold, and thereafter removing the mold to provide a reinforcing plastic water heater body.