Good news!

I'm a complete idiot. I should have obviously assumed that, though one pipe was red and the other was blue, the controls for the shower were reversed. D'oh. I have now achieved a mildly lukewarm shower, which is better than bone-chilling, so I'll settle. For this same reason, I have walked towards the wrong escalator at least a dozen times, and thank goodness the streets have signs that say which way to look, or else I would be road kill by now.