Why do coffee maker instructions tell you to start with cold water and not hot?!
Why do coffee maker instructions tell you to start with cold water and not hot?
Answers:
Some of you are close, but not exactly on the button. Water heated, and kept hot, in a hot water heater concentrates minerals and impurities in the water. If you have seen a heating coil, you will see that it is coated with calcium, etc.
If you draw water from the hot water faucet, you will get this mineral concentrated water.
There are still minerals in cold water, but at a much less amount.
True coffee drinkers claim they can taste the difference. I can't.
It has something to do with the internal part that heats the water, apparently it can be damaged by hot water. Probably warm tap water once wouldn't break it but since it is not recommended I sure they have good reason.
Also they are probably trying to keep morons out there from adding boiling water which would definitely hurt it.
Cold water has fewer impurities than hot because it has not been through the water heater which can add minerals.
It's the same reason they use hot water to make ice cubes.
Because the electronics inside will be messed up and the sensors will be damaged.
Because straight hot water ruins the taste of coffee.
I tend to think that people would use excessively hot water, not just warm but near boiling. Some of the seals on the cold water side plus the reservoir are probably made of a plastic which would warp or deform if hot water was used very much. However when i make coffee/tea i start with hot water, since it takes less energy to bring the water up to a boil. You use less gas/electricity/fuel so it is more efficient and 'greener', which might help reduce co2 in the long run.
the reason they say start with cold water is the same reason when you want to boil water on the stove you use cold water. The molecules are closer and more uniform in cold water and thus heat up more quickly than hot water. hot water's molecules are scattered and therefore react slowly to more heat. it may sound retarded but thats how it actually works. i think it has less to do with the machine components and more with getting your coffee quickly. The mineral thing doesnt really matter because the minerals are in cold and hot water. you taste them more in hot water because (again) the molecules are scattered and are not holding onto the minerals. so the mineral build up will be the same regardless of whether you start with cold or hot water.