We had a person concerned about the recirculating water used to cool the LEDs being returned to hydroponics as waste heat. The recirculating water used to cool the LEDs has no measurable waste heat. The thin steel pans with large surface areas dissipate heat from the lights at the case for the LEDs mounted directly to the steel with a thermal adhesive. The large surface areas of water on one side and steel on the other effectively reach a thermodynamic equilibrium with the controlled environment that has temperature and humidity control. The recirculating water had no measurable temperature change with the lights on or off measured with a Fluke Model 179 Multimeter that has an integrated temperature probe with a thermocouple that measures -40 to 260 deg C.
Heat from LEDs recirculates to the top pan, and is re-used for that germination area. We eliminate the heating pad that others use for their germination area. The thermodynamic design with cooling from the recirculation of water eliminates the active cooling that others use with nearly 40 mechanical and electrical parts including steel chassis, power supply, machined aluminum heat sink, and fans. Our system is the most efficient system regarding energy and cost on the market today. We reduce waste in heat and electrical energy. Our power supply operates at 95% efficiency with no loss in the electronic dimmer used to match the LED output to the measured photosynthetic photon flux density (PPFD) at the plant canopy. This closed loop tuning of the light to the plant is the most efficient method possible. Our LED has a output (PPFD) of 4600 umol/m^2*s at the surface measured with my Quantum PAR Meter. When a plant needs 800 umol/m^2*s at the plant canopy at a distance that varies as the plant grows, we are able to tune in exactly what the plant needs without any waste. Our research involves light frequencies outside the currently measured 400 – 700 nm for photosynthetically active radiation (PAR). One specific frequency produces a 20% increase in crop yield that is non trivial.