as these fans present a thin profile for installing on panel 42 the attachment enclosure 40 panel 42 heat exchanger 50 piping 300 and fans 202 202 u2032 then installs on a rack enclosure not shown fig7 illustrates an embodiment of a modulating valve and piping arrangement 300 according to the present invention adapters 302 302 u2032 attach to an external cooling source not shown the external cooling source supplies cooling fluid such as water glycol or dielectric fluid to the heat exchanger not shown a tee 303 connects adapters 302 302 u2032 to supply line 304 supply line 304 has connection end 306 that connects to the heat exchanger as shown in fig6 b after passing through the heat exchanger and absorbing heat cooling fluid leaves the heat exchanger through return line 340 a return opening 342 on return line 340 connects to the heat exchanger and receives the heated cooling fluid return line 342 connects to one coupling of a modulating valve or thermostatic valve 320 thermostatic valve 320 also has a second pipe a supply pipe 330 attached supply pipe 330 connects the thermostatic valve to supply line 304 thermostatic valve 330 has a thermostatic operator 322 that.