I have been pondering a coolant loop control via thermostatic mixing valve. Unless someone chimes in with negatives that I have overlooked, I'm tempted to get one and see if I can make it work.
The idea is to circulate cooling water into the mix port on a non-anti-scald thermostatic mixing valve and plumb the "cold" side to drain. As the cooling water heats up the valve will bias and drain the excess hot water while cold makup water is added to the pump suction in combination with re circulation water. Conversely, if the temperature is below the set-point the cold side of the valve should close up and decrease flow to the drain. When the loop is at the set-point the valve should split 50/50 drain and recirc meaning the makeup water is mixing with the supply water also at 50/50.
The trick will be to find the set-point on the valve(s) that provides adequate condensation.
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I'll try running some math on it and see what I come up with.
I have a thermo valve from a photo lab. It is designed to mix hot and cold to keep a constant temp. But it looks like your drawing is changing the use/direction of the connection ports.
Mine is cold in + hot in mixes for tempered out.
I'm not sure the springs will react properly if flow is changed.
That's why i need to try the older non-antiscald vesion. They dont have the pressure balancing spring, only a thermostatic wax plug and singlespring, similar to a cars thermostat. Instead of opening and closing like in a car it adjusts the orifice ratio between the two ports. Think of it as a left/right diverting valve based on temperature. It should have a constant Cv no matter the temp.
