Thanks Greg. Yes when it gets really cold, like in the teens or below I am worried about one section of the existing system at the far end of the house. Option one is to completely bring the system off-line. Drain the baseboard pipes and not worry about it. Another option is to run the circlulating pump only, to reverse heat the water in the system. and third is to crank up the kerosene heater in the garage to warm up the floor in the far end of the house.
As far as the boiler is concerned, this one in place is 22 years old and ready to be replaced. I picked up a used oil furnace last year but haven't done anything with it yet, so I'm not really concerned if the boiler gets eaten alive by the sulphuric acid. Maybe I will just leave everything in place as is. Easy button!
I have a feeling heating oil will drop in price if we get a warm spell in the middle of winter. Then I can at least fill my tank up one last time!
Good to have something in place to keep the house warm when away for a weekend and such.
Maybe in the spring, I can try out this idea, after the cold part of winter has passed!