westend wrote:
The fuses are there to protect the circuits involved. The pressure relief valve is installed to protect anyone close to the tank, should the pressure rise to a setpoint. This eliminates tank explosion.
A few years back, in St. Paul, MN, IIRC a homeowner installed a 60 gallon electric water heater without a pressure relief valve. He thought it was only an accessory and he didn't need to have one. Something went amiss with the electrical circuits and the water heater continued to heat and pressure rose. When the heater exploded like a rocket (the bottom of the tank gave way), it travelled through the first floor kitchen from the basement, killing the dog there. It continued through the second floor bedroom and finally exited through the attic and the roof. It landed 200 yds away in the neighbors yard. The owner and his wife survived the explosion but it took out every window and door in the house.
Do you think having that relief valve isn't necessary?
Mythbuster tried this, results below. Truly impressive explosion.
https://youtu.be/9bU-I2ZiML0
