The really nice thing about the insulation is that they make pex staples that go into it to keep your tubing in place until you do whatever it is you're going to do over it (like pouring concrete). The tool allows you to stand up and just walk. Very cool and very rentable from any pex dealer.
Here are some specs on my heat exchanger I'm going to use for my WVO which measures approx. 8"x5"x4" or so.
Water to water
50,000 BTU output (about the same as an underseat heater)
Input: 5.08 gpm@180*
Output: 1gpm@40* to 140* rise
So....you can get water from almost freezing to 140 degrees using a very minimal flow from your coolant. Flow more coolant (like the 60gpm our water pumps are capable of) and you can REALLY heat a large volume of water rapidly.
If you can't tell, I'm in love with high turbulance couterflow plate heaters.