Runs with Bison
Member
You were likely just feeling the heat being released by your body getting trapped under the insulation. I wouldn't attribute this to the heat loss of the tank.
Wrong. Any time you put significant insulation over a primary source you will find that the temperature between is now closer to the source (in this case the water heater tank.) This is introductory heat transfer. Seriously, all animosity aside, if they offer trades courses in this I think you would both benefit from and enjoy them--plus I think it would help your customers in the long term. You seem to have a strong interest in the subject, and that is a positive thing. If you mastered the fundamentals of heat transfer and some basic fluids you would have a leg up on many engineers who never seem to get it (in my design group we used to laugh about those engineers who didn't seem to appreciate the 2nd Law of Thermo when doing heat exchanger design.) I'll take a well informed layman with passion for a subject over a disinterested person supposedly better educated in the subject. You've already got the passion, so do something constructive with it.
I can see the resistance effect in everyday terms when putting a blanket next to an exterior wall, or a pillow on the floor of my uninsulated floor above garage in winter (both surfaces will feel colder beneath than surrounding areas when the pillow is removed.) Same is noticeable at the water heater (hotter) and also on top of my chest freezer when I set something on top (colder.)
Obviously it isn't body heat making it feel colder in the cases with a cold source in previous examples. An average Joe with a good high school/trade education, or years of experience can appreciate that aspect without a fancy/expensive degree.
By the way, the same is true in a scaled water heater. Once the scale exceeds the critical thickness of a few mm's the wall temperatures begin to rise. This isn't a problem for a long time, until the scale is sufficient to overheat the wall to the point of rapid corrosion and/or significantly reduced efficiency. The result is a death spiral. I've seen this same sort of process in various types of process heat transfer equipment and am not bad at figuring out ways to prevent, anticipate, or mitigate it. I've also seen poor pH control eat the magnetite film in a high pressure boiler...the resulting tube failure with black soot mushroom cloud and firebox bricks flying about was exciting, but expensive for the facility. Once I modernized the boiler feedwater control and retrained our operators the longstanding problem didn't reoccur, plus we minimized our blowdown losses. Win-win.
Furthermore, I carried the boiler stoichiometry of this same process over into the refining section of the plant and solved some 40 year old problems with it that escaped some brilliant engineers...including the CEO of my multi-billion dollar employer who had worked on the same projects on the same unit. I'm not necessarily the smartest guy in the room, but I'll catch some things he never noticed...
Patience, Grasshopper...