Someone smarter than me may know, but I think you will have a hard time finding a unit that does both pellets and wood/coal without some work to make a switch-over. You can get a coal/wood unit easy enough, but due to the necessity of a system to stoke with pellets and control accordingly, I dont know that you can find a three-in-one unit.Varmebaronen makes a combo unit that will burn pellets on one side and cordwood on the other, but I dont know how its efficiency is. IRLEH makes a unit that will burn biomass/wood/coal, but I dont think it does pellets.
Ok thank you I will have to. Find one or make a choice it lookalike
It sounds like you currently dont have any type of hydronic heating system in your house currently, so you would have to install all the piping, which could be an expensive endeavor, depending on the size/configuration of your house... You may want to look at underfloor radiant, which might be the least disruptive if you can get to the bottom of your floors, and then you could even supplement that with something like a water heater when you are away.
If you are just wanting to heat with wood/coal while you are home, would a wood stove or wood/coal combo unit work for you in your main living area? Lots cheaper to install, provides great heat when you are there, and the electric could stay as your backup source for when you are away.