This submission from Jason Crawford begs the question: Why?
Three buttons for two commands is silly. My best guess is for safety reasons, they want two buttons involved to reduce accidents.
But as Jason points out, why hide the choices in coded letters?

If it had two buttons for safety reasons, wouldn’t it make more sense to position the buttons such that both hands are required to press them? I know they do that on some kinds of heavy machinery.
or just change the color of the buttons: Red for hot and blue for cold
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Now I’m also wondering what those 3 little green lights mean.
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