Originally Posted by
Jon Randolph
I would say the friction of the water circulating around the pump caused the heat (in combination to the heat from the motor). The float is stuck and there is simply nothing to pump out. I would not suspect a plugged discharge unless the pit was full. Pumps can only pump out to a certain level, as little as 1/2" depth for some, much more for others. When there isn't enough depth for the pump to prime, it will cavitate. Cavitation and the friction of the water molecules creates heat. If water were coming into the pit, the water would be much cooler, probably around 50-55 degrees.
BTW, I would recommend replacement of the pump as they are not designed to run continuously for long periods of time.
Now, I'm not a molecular scientist but I would think that in order for the friction of water molecules needed to warm cold water to 103f you would need something on the scale of a hydroelectric plant to generate that amount of heat.
Just about every sump pump I have seen are sealed pumps(oil filled) that are cooled by the surrounding water that they are submerged in. The pump case transfers the heat to the water. Logic would say that if the pump is running continuously without the addition of a good amount of cool water, and it is not discharging then the water in the sump would become warm after awhile, just like you are finding.