Mark, Im just asking here, not arguing......... Using your math, it looks like the hot water giving up its energy releases a very small amount (834btu) of heat then to the air (right?) However, you're showing that it takes a fair amount of energy(8000btu) to make the cold water get hot and give up its energy to the air (right?) Here is the problem then: To make the water hot takes a lot of energy because you are using a water heater. Yes I know a water heater has hot water in it already but if it doesnt have to be used then it saves you that much money. If you use a furnace it already has to be used whether you are going to use a humidifier or not because you want your home warm and comfortable. The 8,000 btu is given up to the air stream so it is not actually lost. Thus I still dont think it is worth using hot water for a humidifier and what I tested did not show a 10% loss of excess water. Your math figures may be correct, I dont know, but it just doesnt work out that way in the real world. Most people dont have 150 water coming out of their water heater. Thats a lot of energy being wasted and can scald someone.
120 to 125 is normal and recommended. It takes 2 seconds for a child to receive third degree burns from water at 150 degrees. It takes 5 seconds if the water is at 140 degrees, and 30 seconds at 130 degrees. Bubba