I have read (thanks to Stack Exchange) that mixing water and sulfuric acid is exothermic, as is NaOH and HCl.
Are there two 'safe' liquids that can be mixed and produce anywhere near the same amount of heat? By 'safe' I mean they don't come with the same heavy warnings as sulfuric acid or lye. I would like them to be safe enough to be stored in a home and that a spill would probably cause some damage but clean up could be performed by the home owner safely.
I understand that the actual mixing might not be considered safe if they do release a lot of energy.
I'm only considering liquids because they can be kept separate and pumped together.