Indoor wood boiler tied into current oil/hydronic system?

Here is the manual for Tarm Solo but I imagine it would work for any wood furnace. Page 16 and 17 look like what you want.
http://www.woodboilers.com/images/stories/documents/woodboilerplumbingschematic1211.pdf

My primary heat exchanger is two 120' coils of half inch copper hooked in series to function as a 240' coil that both puts heat in and takes heat out of the tank, as I understand it. My DHW is provided by a separate 180' coil of 3/4" copper, and I love the simplicity of it. The feed comes in from the well to the bottom of the tank and simply rises up through the coil. There is a mixing valve where it exits the tank to keep the temp down to the setting of my choice. The water in the tank is simply a heat sink that doesn't go anywhere.

"The water in the tank is simply a heat sink that doesn't go anywhere"

I like that idea. A colleague at work has an outdoor boiler and he told me that the system is open-that the water is pumped through the boiler and the baseboards and slab pipes and is open to atmosphere at the boiler. I'm not so sure I'd be to keen on that.

Plus, I don't know how I'd fit a propane tank through the 36" door opening. One of those heat banks might fit the bill.