This looks to have turned into a discusion about water backs or heating water from your heating stove.
I have an old coal range with a water back or casting full of water in the side of the fire box, this was side armed on a forty gallon uninslulated tank all plumbed with 1" pipe. This stove was basically my only heat sourse and in the coldest part of winter it would gurgle and simmer along and I would flush the toilet lowering the water preasure and then it would really grumble and spit steam at the faucet till the well pump cut in and settled it down. I would then ether take a shower or do laundy. I then went to putting a fan on the tank blowing cold air from the floor up the tank and this seamed to cure the problem, till I put a stoker fired boiler in the garage, indirect hot water tank and removed that water back from my stove.
My family has a past with water backs. Not sure what relative it was but he replumed his house when he recived electricity and added an electric hot water tank, removing the side arm tank. On first firing of the stove his wife complained of water coming out of the stove as it warmed up, he grabbed his supplies and plugged both holes in the water back. It exploded while he was out getting wood and she was trying out her new washing machine in another room. That was back in Washington State early 1900's.
Around town here where power didn't come untill 1986, some still talk about side arm tanks gurgling and spitting steam in the coldest part of the year.
If you heat water you need ASME ratings, relief valves, and some comon sense, especially if it is hand fired, based on room temperature. If I did it again I would put the tank in another room, to spread the heat around the house and add a dump zone of some kind with a mechanically operated valve and gravity circulation.