Hello all, I am looking to add a heat dump to my domestic SHW system. I am looking for a non electric valve that has a thermostat in it... so that when the temp of the loop hits a certain level, the valve allows the heated glycol to run through a radiator so it can cool down without adding more to the solar storage tank. I keep coming up short when trying to Google this valve, does anyone know the name of the valve I seek? Thank you for your wisdom.