Sometimes the top heating element gasket can become faulty and cause the lower element to leak and this will cause moisture to build up and short out the lower element.
Yes install it on the cold water line as close to the heater as possible.
bottom element is probably bad. another sign of this is that you run out of hot water fast.
You have a major electrical problem.. If a breaker trips more than once you need to leave it off and call an electrican.
Heater blower motor is defective and locked up, or possible short in the wiring.
It will keep the water hot as long as the electricity or gas is on. If it's going to be off more than a day, turn the breaker or gas valve off.
There is an electrical short to ground in the fan switch or in the blower motor itself.
There's a short in your main line going to your fuel heater.
If your having condensation at the bottom of the unit it could be that the bottom element has gone bad and when the cold water comes in and hits the warm tank it is condensating. Also if heating element has gone bad that could be a definite cause for the breaker to keep tripping.
Have somone hold a hot cup of water and blow it towards you. This will keep you a little warm. It would be bad if the person had bad breath.
could be head gasket problem. does your heater work? might need heater core , clogged up. do compression test. or bypass heater core and see if that works.
Beause there is probably a short/bad connection in the switch, or the blower motor itself
Could be, Low on coolant, A stuck open thermostat, A plugged heater core, A faulty temp blend door actuator,