While looking in entirely the wrong part of the code for that, I also ended up removing a couple dozen lines of code that could be replaced with 4.
The problem was an out of date constant which should have been replaced with a variable but I missed it in one spot.
Needed to adjust the thermostat on the water heater today. I'll need to keep an eye on that as I've adjusted it to about half way between where it was set and the Hot setting. Instructions say don't go hotter than Hot despite the presence of 6 higher settings ending in Very Hot. I'm looking for hot enough for the commercial dishwasher to behave properly and not so hot that it's uncomfortable for humans.
(the algorithm is nothing original, it was just faster for me to rework the details on paper than it would have been to check reference material)
Author of Typica software for coffee roasters.