Heat Pumps FAQ

Yes. They can heat entire homes or businesses as long as they are located and sized properly.

Yes. The high efficiency units that qualify for Efficiency Maine rebates work well in cold weather. Some are rated to work down to -15°F.

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Heat pumps and furnaces provide heat in different ways. Furnaces send hot air to the house in bursts, while heat pumps provide warm air for longer periods of time. The total amount of heat is the same, but heat pumps produce the heat more efficiently, and the steady heat can improve comfort.

Heat pumps use electricity to heat your home, so their carbon footprint depends on the power generation that serves the regional energy grid. The mix of generation that serves the grid in Maine is among the cleanest in the country. If you have a heat pump that offsets just one third of your home’s annual heating load, and if you heat with oil like most Mainers, the heat pump would eliminate 2,400 pounds of CO₂ per year, the equivalent of eliminating the carbon pollution from three months of average driving. The more your heat pump offsets your home’s heating from fossil fuels, the more you will reduce your carbon emissions.

In cold weather, heat pumps will occasionally run through a short defrost cycle to remove ice from the outdoor unit. When this happens, the heat pump temporarily stops producing heat. The defrost cycle lasts for only a few minutes and is part of the normal operation of a heat pump.

The indoor and outdoor units of a heat pump are connected by copper pipes that carry refrigerant between the two. As the refrigerant moves through the pipes, it can produce a gurgling sound. This sound should not be cause for concern. It is part of the normal operation of a heat pump.

To see how your costs might be affected, please visit our Compare Home Heating Costs calculator. To maximize your savings, follow Efficiency Maine’s Heat Pump User Tips.

High-efficiency heat pumps perform the same functions as five different appliances: heaters, air conditioners, dehumidifiers, ceiling fans, and room air filters.

No. Though high-efficiency heat pumps may be configured to work as the sole heating system, they are often used to supplement an existing system (for example, by installing a heat pump in one room and using the central oil boiler system to heat the rest of the building).

Yes, for some heat pump/boiler combinations and electricity/heating fuel price ratios there is an outdoor temperature below which the boiler burning oil or propane is less expensive to operate. Our modeling has shown that using 2018 energy prices, the transition point is somewhere between 5F and -15F. Switching back and forth exactly when the temperature crosses the transition point could save up to 5% on heating costs. However, forgetting to switch back to the heat pump once the temperature climbs back above the transition point could end up costing more. Therefore, we generally recommend that you select a temperature set point on the heat pump that makes the room feel comfortable (usually several degrees higher than what you have used with your central heating system thermostat) and leave it at that setting throughout the winter.

Qualifying units are more efficient at producing heat than non-qualifying units when outside temperatures are low. This enables qualifying units to produce more heat than non-qualifying units.