No main flame, bad thermocouple, power outage, valve shut off , bad heating element, tank aqua stat set to low, tank does not have enough volume, sediment build up inside the tank ,electrodes encased with mineral deposits, no return circulation, T&P keeps relieving thus wasting H/W, electrolytic action blocking either the inlet or outlet. Tank leaking
Hot water causes the jar lid to expand.
Because the water is hot!
boiling hot water
means you are running out of hot water
hot water has faster moving particales than cold water
Expansion and contraction
Hot air full of water vapour.
You are running the water heater out of hot water faster than it can heat the incoming cold water.
if someone put in a hot water tank they may have the lines switched.
brownian motion
The flow of molten magma is what causes varying hot spots on Earth. Hot spots are also known to heat water beneath the ground.
when your engine is hot it causes the water to boil and the water and the anti freeze will come out of the overflow pipe.