Does Low and High pressure vary under different operating condition

Hi,

I'm running a 4 ton R410A water to water heat pump. Under full load condition, my source water is entering at 43F and leaving at 38F. My source of water is coming from a lake. The evaporation temp. is set to 30F which give me a COP around 3.8. The system is equiped with a pilot control TXV.

Now my question is , what happen later in the year when my source water enter at 60F. Does this extra avalaible heat only superheat my refrigerant. But in fact only have marginal impact on the system COP. Or does the low pressure increase to take advantage of the extra heat available and therefore reduce the work accomplish by the compressor which finally translate to a better COP.

I'm not sure if low and high pressure vary along the way according to the heat available in my water source ??

Could someone help me with this?:(

Your COP will increase as your TEV will try to maintain a stable SH of +/- 5 K
Every 2°F temperature increase of your TE will result in +/- 2% energy decrease, so a COP increase. How do you set your evaporating temperature to 30°F