Yes. If you have an open loop system, your entering water temperatures (EWTs) may range from the 70s in the southern United States to the 40s in Canada. All heat pumps can handle temperatures in the moderate-to-warm range. A closed loop system, on the other hand, may encounter EWTs below freezing. Not all geothermal heat pumps will operate efficiently at those temperatures. It’s important to know what EWTs at which your heat pump will operate most efficiently.