I don’t know about anyone else, but I pretty much never use my faucets on the hottest temperature. In fact, I can’t, because it’s really painful and I’m pretty sure can cause actual burns if you hold it for long enough. For bathing and hand washing, I typically turn the faucet to anywhere from the half to two thirds hot point, any more and it’s uncomfortable.
Which got me thinking, why is domestic hot water that hot to begin with? Why are we spending energy to heat it to a point where we can’t comfortably and safely use it without cooling it back down with cold water? Wouldn’t it make more sense to heat it to no more than a comfortable showering temperature, and just use the faucet on full hot water? Not only would we be using less energy in the water heater (and less CO2 emissions if you’re using a gas water heater or an electric water heater with the electricity from a nonrenewable source) less hot water would also lose less heat in the pipes and water heater itself, because the rate of thermal energy loss is directionally proportional to the temperature difference between the hot and cold regions. And water heating is one of the biggest energy consumers in the residential setting, so reducing it would be pretty significant.
And, if the water pressure in your home fluctulates a lot, by avoiding the water mixing step, you avoid the issue of the cold water pressure suddenly dropping and the temperature at the faucet spiking and burning you (I lived in a university dorm with really unstable water pressure, and it was a constant problem). You also avoid that thing where you turn your faucet too far to the hot side because the water in the pipe is cold, and then having to adjust it a hundred times to maintain a comfortable temperature as the cold water in the pipe is flushed out.
Most water heaters let you turn the water temperature down pretty low, so there’s no real technical reason you can’t just have it make “kind of hot but not scorching water”. And in the rare times where you do need really hot water, you can always just boil some on the stove, and still save energy overall because you won’t have to do it very often.
What do you think? Should this be a change worth making? Any drawbacks that I’m not thinking of?
Where I live, the ground water is cold enough that you need a heavy duty tankless if you want an electric one. The alternative is a gas version, but I don’t really want to add a gas appliance to my house if I can avoid it.