Hey guys a friend of mine has made a hot tub, its simple, just a container for your water with copper pipe coming from the top and bottom of the tub (but both below the water level) and they are attached to house radiators and you start a fire under the radiators and the heated water rises and exits the highest pipes thus sucking in cold from the bottom to heat up, no pump required, I was wondering if you ran the pipes through a wall and to another radiator could you use your cooking fire to also heat a radiator and give you central heating??? Elther way this will make a nice warm bath possibe at least , I know a fire with a chimney would mean you don't need your fire outside anyway but I just think the idea is quite good, it is also painfully slow to heat up but if ur having a fire anyway then there's no harm in adding one of these to it surely