If you’re new to homeowning, you may wonder, “What is a sump pump and how does it work?” Learn more about sump pumps and why you need them.

Q. We have the original oil-burning furnace in our 29-year-old home. It’s attached to a tankless hot water heater and supplies all of the hot water for the house, including domestic hot water ...

The pump “pays” for the higher energy water at the output by letting water flow to a lower point. Of course, in this example the pump would be 100 percent efficient—and that never happens.