d includes a cold plate channel 34 defined and passing therethrough and having an inlet 36 and an outlet 38 see cold plate 28 a wherein the outlet 38 is located above the inlet 36 the radiator 30 includes a radiator channel 40 also having an inlet 42 and an outlet 44 wherein the outlet 44 is located below the inlet 42 the cold plate channel 34 and the radiator channel 40 may include more than one channel joined together by air convection fins within the cold plate and the radiator respectively as fluid circulates within the cooling circuit 26 the fluid inside the cold plate channels 34 warms as heat generated by the leds 22 is conducted through the cold plates 28 to the fluid within the channel 34 being heated the fluid is less dense and tends to rise in the circuit 26 upon reaching the radiator 30 the fluid enters the radiator channel 40 and cools as heat from the heated fluid is conducted through the radiator 30 to the surrounding environment preferably the radiator 30 is disposed at or outside of the housing wall 14 and conducts heat from the fluid and the air within the chamber 16 to the outside environment which is at a lower temperature as the fluid.