A neighbor gave me his 40 gallon tank after he installed a HPWH. The internal plastic dip tube which forced cold
water to the bottom had broken off so cold water mixed with hot at the top of the tank. Cold water is now introduced
at the drain port. This is a high lime location, honestly I filled a 5 gallon bucket with sediment. He also gave
several used heating elements coated with lime. These quickly clean up after sitting in vinegar. That sediment with
calcium and magnesium is great for the garden.
I keep my tank on a 15 inch high insulated pedestal. Typicially the bottom of tanks are poorly insilated with three
formed feet which touch the outer wall. The extra height is essential for draining the tank at the end of the season
and I do need to tip the tank. Removing the valve or pioe makes a bigger opening to clean. Washing machine hoses are
used to connect my tanks which make them easy to move. It is a low pressure system and the six gallon tank has to turned
upside down to drain.
Many heating elements are high density (because they are cheaper to make) meaning they get too hot and deposits easily
form on them. A good building products store will offer low density which are about 50% longer. If you can hear your
water heater when it runs it has high density elements. That popping is bubbles forming on the surface and that also
causes the scale to fall off filling the bottom of the tank. Low density elements will not build up as much scale. I operate
the elements at lower voltage which achieves the same result. Lower wattage elements can still be high density, just shorter.
Solar applications see wide changes in tank temperature. System should have an expansion tank to accommodate expansion. My
garage laundry system has a 3/4 inch stack pipe to accommodate some expansion. This is topped with a pressure gauge because
I couldn't find anything else handy to cap the pipe. The detached garage is feed water with a garden hose. In my locality
if I want water at the garage legally, it would have to have a separate billed water meter. Consequently, That hose is
turned off to avoid it splitting when I am not there. I can see the pressure climb an extra 50# in this closed system as
it heats up. Expansion can add an extra quart.
Legionella....... I'm on municipal water so I don't worry about it. My tanks cycle thru wide temperature ranges and have no concern.
I know othere with water feeds from their roof providing lots of neutrients. I won't drink their water with stuff floating
in it, won't even shower. They seem to be fine with it. Most important is how long water remains stagnant in a tank.
This video is the most logical explanation I have seen.