No If the hole is smaller then the diameter of the supply line
It can maintain the cooling temperature of water and 80% of copper is available.
"How much" as a question is quite vague. Some hot water heaters are comprised of copper only. So this now depends on the size of the hot water heater. Some hot water heaters have no copper whatsoever.
It is copper oxidation.
The copper wire used in the solar water heater is wrapped in the shape of the coil to increase its surface area.
A lot less because the water is flowing if it is exiting and it depends on the water pipe size.
By looking at the check or globe valve
Bolt the heater core into place, with the four retaining bolts. Connect the water supply hoses. You might need to bleed one of the hoses to get the water flowing through the heater core.
If electric water heater, usually bottom element going bad. Thermostat might be set too high or is going bad.
Because it is a very good transmitter of heat.
If water is dripping out of the heater core it is about to go.
YES...IF IT HAS STOPPED WORKING IN THE CLOSED POSITION THEN THE HEATED WATER ISN'T FLOWING THROUGH THE HEATER CORE.
The copper pipe in the solar water is wrapped in the shape of a coil to give it maximum surface area.