The water heater dip tube, what it does, how do you know if it is bad, and how to replace it.
only 5 minutes of hot water.
The image above or to the left shows how a dip tube works. The dip tube is the blue pipe on the right side of the water heater, notice that it goes almost all the way to the bottom of the water heater.
The reason, is to force the cold water to the bottom and allow the hot water to come out of the left side of the water heater, notice there is no dip tube on the left side of the water heater.
This image is not to scale and not up to code, it's only purpose is to show how the dip tube works.
A water heater is always full of water, it does not empty, then fill again, the red in the tank represents hot water in the tank, the light blue represents cold water coming in to the tank.
The image shows the tank going all the way from hot to cold, but if you have a water heater with a good recovery, the water heater will be able to keep heating the water, and prevent the water from ever getting cold.
Almost all water heaters have dip tubes, Gas, electric, and oil fires, even indirect hot water makers have dip tubes, there are some that don't, if the cold water line is connected to the bottom of the water heater, there is no need for a dip tube.