discs 18 a through 18 l and 20 a through 20 k are preferably semicircular in form as shown in the various drawings but may be any suitable shape or form so long as rotation of the movable discs 20 a through 20 k relative to the stationary discs 18 a through 18 l results in variation in the closely adjacent surface area between the stationary and movable discs in order to adjust the heat transfer therebetween it will be seen that the twelve fixed discs 18 a through 18 l and the eleven movable discs 20 a through 20 k are exemplary in number and more or fewer discs may make up each set of fixed and rotating discs fig2 provides a detailed perspective view of the fixed discs 18 a through 18 l each of the fixed discs includes a central channel 24 therein the aligned channels 24 of the discs 18 a through 18 l provide for the placement of the rotary shaft 22 therein the shaft 22 is illustrated in fig1 3 5 and 6 a through 6 d of the drawings the discs 18 a through 18 l are supported by legs 26 which in turn rest within the housing 16 shown in fig1 and 5 of the drawings a plurality of peripherally disposed interconnecting tubes 28 extend between adjacent fixed discs 18 a through 18 l and connect each of the fixed discs in sequence that is to say the first fixed disc 18 a is fluidly connected directly to the second fixed disc 18 b the second fixed disc 18 b communicates fluidly with the third disc 18 c and so on in.