In fairness to Rheem, the way the app didn't work WAS pretty funny. See, it made you register with them before you could schedule your water heater. So first it'd ask you what username you wanted.
I'm not gonna tell you my Rheem username, you'll have to wait for the inevitable data breach for that, so let's say it was ifixcoinops. So you tap the box (you have to do this on a phone, you can't register in a browser) and you tap the letter i on the keyboard and a little i pops up on the screen, quite clever really, then you press the f and the text hole has iif in it. Hmm. Alright well the next letter in "ifixcoinops" is another i, let's press the i on my keyboard, the text hole now says iififi.
Which is slightly unconventional, but okay, let's see where this is going, iifiifiiififiifix. So I introduce myself as mister iififiifixifixcifixcoifixcoiifixcoinifixcoinoifixcoinopifixcoinops, and it tells me there's not enough digits in my phone number