This is the one thing I am concerned about since we are just getting into the pellet scene. We have hot water/baseboard. I know the boiler has anti freeze in it, just not sure what it is rated for. No pipes in crawl spaces etc. So no worry there. Outside walls are the only issue as I see it. We are puttling a stove in the basement as well as an insert upstairs so hopefully that will help prevent any problems. In addition, We have 4 different zones in the house. So my plan is to keep the ones furthest from the upstairs stove set at a temp that will cause the boiler to push heat if the temp in the room falls below a certain temp. Hoping we don't have any of the problems listed here. Looking forward to the pellet heat.