Most heat pumps look like central air conditioners - a metal box outside your home that's about waist-high. Here's a good picture of an air-source heat pump and information about how it works.

Besides going around outside to look for a metal box, the other give-away is that heat pumps, despite the confusing name, can both cool your home in the summer and heat your home in the winter. So if you've got a thermostat that you can set to heat or cool your house through forced air ducts, that's a good sign that you might have a heat pump.

Lastly, heat pumps are more common in southern parts of the United States than they are in northern parts like New Jersey. That's because most air-source heat pumps can't keep your home warm enough when the outside temperature drops below 40 degrees. In New Jersey, where the average low temperature in December - February is below 40 degrees, most people that have a heat pump would need a backup furnace as well.