With the cost of copper tubing for hx vs the cost of flat plate hx's, I'm wondering what are the +/- of copper tube vs plate hx. Also, are there distinct benefits and disadvantages depending upon application? I realize the flat plate requires a second circulator pump. I bring this up in part because with 110 input water to my plate hx, and 170 boiler input, my hx output is 165, just a 5 degree difference. As hx input rise to 130, hx output is nearly 170. I'm using a 5 x 12 x 30 plate hx, 1" inlet/outlets, Taco 007 on the output side, Taco 009 on the boiler input side.