Most Efficient way to get storage water to zones

[stokes79]

I don't know if this makes a difference, but right now I have three manifolds, two staple up and one in concrete slab, then my indirect DHW tank the two staple ups are 140 max the slab less than that and domestic is all copper so temp doesn't matter.

My question is this, If I charge my tank and it is at 180 my manually set mixing valves bring the water down to 140 but then when my storage temp falls to lets say 120 is that same manual mixing valve still dropping 40 degrees? Is there a better way to plumb this?? I guess any tempered BTU's through the mixing valve end up back in storage so am I really loosing anything except in my piping and storage losses?
thanks
casey

 

[2.beans]

taco makes a mixing valve that adjusts to outside,inside and water temps automatically. i think its called an I valve.

 

[Chris S]

My understanding is that a thermostatic mixing valve acts similar to the way a car thermostat works, so no it is not dropping the temperature 40 degrees. If your storage is less than the temperature you set the valve for then the return water will not enter the valve. You will get a full stream of supply water whatever temperature that happens to be.

Check your temperatures to confirm this