The advantage of plan A is
I can use wood for heat
wood is free
I live in a woods
I'm also a timber frame and log carpenter
Wood is free. I have lots of wood.
I want to design a system that allows me to use wood, but satisfies state legal code for cheese make rooms -which means I can't use direct wood heat.
I also want to use the free-hanging vat rather than a jacketed steam or hot water vat. This is because I plan to have an exhibition cheese operation where people can look at it, and I am really trying to replicate the Alp methods. Also I learned how to work in such a vat, I know the tricks and get get precise results in such. I want to work with what I know.
And then there is the romance of the idea of using the old style of vat.
So I am willing to sink some money into a system that will allow me to make use of my free heat source and let me use my hanging vat.
I am trying to work out the kinks right now, working on the concept of a high efficiency condensing boiler system (where the heating coil first passes through the exhaust flue to absorb waste heat) with a ballast tank before the furnace -basically a vented reserve tank to regulate temperature and pressure.
My thought is to drop the oil temperature on the input side of the furnace, yes this will drop efficiency but again fuel is free. What this will do is create a greater heat imbalance throughout the liquid, which will increase the natural convection of the fluid. The higher the coefficient of difference, the greater the draw by convection will be. I'd like to optimize the whole system to eliminate the need for a pump. Also having a tank of cool liquid on one side of the system will help to ensure convection goes in the direction I want it to. Again, I have to create a system as out-of-balance as I can.
Some aspects are inefficient, like dropping the oil heat as much as I can before reheating. So I am trying to make up the difference by using a higher efficiency boiler system.
I would also place a bypass valve inline before the radiator coil, this would allow me to effectively shut the heat off on demand by sending the hot oil through another pipe, giving me more rapid control of the process. I feel this is safer than simply having a stop valve. There would also be a regulator valve allowing me to have some control of flow rate. I would install some kind of limiter on this valve so that it can never be completely shut. I want to prevent overheating my fluid, especially if it is something like oil.
The propane burner is simple and easy. But last winter LP got over $6 a gallon, and there was a shortage of supply around here (-20 degrees for 2 or 3 weeks, 30 mph winds...) This would be expensive over the long term but is a suitable temporary solution.
The methane generator is also a consideration. I will have a lot of input material for this and have explored the idea. I hope to build one in a few years to supply all my heating, cooking, and hot water needs. Also perhaps a limited amount of 12V power.