Hey there, I honestly don’t know if this is the right place for this, but I figured I would ask.
lets say you are going to take a bath, but someone just took a shower and you know your hot water heater will be running low on the goods.
Just for arguments sake, let’s say you have just enough hot water to fill half the tub, so a 50/50 split.
Would it be a better idea to first use all or most of the hot water and add the cooling/cold water later if the goal is to maintain the hottest bath you can? Or would that make the tub just as hot as if you filled the whole thing with equal parts hot and cold water from the start? Would the larger body of hot water filling the tub make the cold water added later warm up faster than if it just mixed in the pipe?
thanks again for the help, if this is indeed the right place for it!
Hi, thanks for asking this interesting question. It is indeed related to thermal science. :)
In both cases, the temperature at the end of mixing will be same, because the water will attain an equilibrium temperature after some time. (Somewhere between cold and hot)
It all comes down to how much time you have to fill the water or mix the water. If the amount of time is not very large, the process of mixing should not matter as much. The temperature at the end will be the same in both cases.
The temperature attained will only depend on the hot and cold water temperature and nothing else. The process does not matter as long as the atmospheric conditions are not extreme.
For example, if the temperature of the room is very very low compared to the hot water then the, if you pour the hot water first the hot water, will lose some heat by convection and radiation because of the large temperature difference.
But, in most cases, the difference between the water that we use for taking a bath and the temperature of the bathroom is not very large. So, it depends on where you are in the world and what is the climatic condition.