Hey guys, thanks for all the input about the antifreeze. However, my system is now fully complete and up and running without one drop of the stuff.
I understand what you are saying about having a exchanger and only putting the antifreeze in the floor and being able to shut it down and let it be for periods of time without worry. BUT, isn't there some concern about letting the concrete get real cold if not freeze and then blasting it with hot water when you want to heat the building?
I will be using the building on a nearly daily basis and it also is used to park daily drivers so the benifits of just keeping it a constant 50 degrees or so and then bumping it up when I will be out there working seems fitting to me, also I have supplies to store out there that should not freeze or go through many changes in temp.
My main take on the antifreeze is to prevent, or protect the entire system including the OWB from freezing if say, just like what happened last weekend out east and I am without power for many days when I and not home to run the generator.