Patent ID: 7036825

Claim:
A heating and ventalation and air conditioning system comprising; a casing including first and second sections of plastic material, a blower in said casing for moving air through said casing, a heat exchanger in said casing for exchanging heat with the fluid flowing through said casing, a joint for sealing said sections together to prevent leakage of the fluid flowing through said casing, said joint including a groove in and extending along said first section and a tongue extending from and along said second section to a distal end in said groove, said tongue having a wider dimension than said groove to provide an interference fit of said tongue into said groove, said tongue having a slot extending into said distal end thereof for splitting said tongue into first and second forks to compress said forks together by said groove as said tongue is inserted into frictional engagement with said groove to narrow said slot from top to bottom to retain said tongue in said groove.