Short answer: Yes.
Longer answer: Yes, when they are properly designed for Maine.
There is still a lingering belief that heat pumps only work in mild, more southern climates. That may have been true decades ago. It is not true today.
The modern cold-climate heat pumps installed by Royal River Heat Pumps are engineered specifically for northern winters. The real question is not whether they work. It is how they perform when temperatures drop, and whether they are installed correctly.
How Cold Can Heat Pumps Still Work During Maine Winters?
Heat pumps do not “shut off” at 32°F. Even when outdoor temperatures fall well below freezing, there is still heat energy in the air. Cold-climate systems are designed to extract that heat and concentrate it indoors.
That doesn’t mean that your heat pump will continue running like it would at 40°F. As temperatures drop, two things happen:
- The system’s heating capacity gradually decreases.
- Efficiency declines compared to mild conditions.
However, the Mitsubishi Electric heat pumps installed by Royal River Heat Pumps can deliver their full heating output even when outdoor temperatures drop to 5°F. They are designed to continue operating at temperatures as low as -13°F, rather than shutting down when it gets extremely cold. In southern Maine, the majority of winter hours fall within the temperature range where these systems operate very efficiently.
Extreme subzero stretches do happen in our area, but they represent a relatively small portion of the overall heating season.
What Happens During a Maine Cold Snap?
When temperatures drop into the single digits or below zero for extended periods, a properly designed heating system continues running.
In homes where heat pumps are acting as a supplemental system, the existing oil or gas system may assist during the coldest hours. That’s by design. A supplemental system is intended to handle the majority of heating throughout the season while preserving backup capacity for extreme conditions.
In properly sized whole-home systems, heat pumps are selected based on the home’s heating load, insulation levels, and airflow characteristics. The goal is steady comfort, and we’ll never install a stand-alone heat pump in a house if we don’t think it will keep that home warm all winter long.
What Is Heat Pump Defrost Mode?
During winter operation, heat pumps periodically enter defrost mode.
When the outdoor coil becomes frosted, the system temporarily reverses operation to melt the ice. You may see steam rising from the outdoor unit or hear the fan slow down briefly. Water may drain from the bottom of the unit.
Defrost cycles are automatic and typically last only a few minutes. A properly installed system returns to heating mode quickly without significant impact on indoor comfort.
Why Do Some People Think Heat Pumps Don't Work in Winter?
In most cases, it is not the equipment. It is the installation.
We have seen heat pumps oversized just to qualify for rebates, undersized to reduce upfront cost, or placed in locations where airflow cannot distribute properly throughout the home.
In those scenarios, the living room may feel warm while bedrooms lag behind. Or the system may struggle during cold stretches because the home’s insulation and air sealing were never evaluated.
When a system is designed based on building science principles and accurate load calculations, heat pump winter performance looks very different.
How Royal River Heat Pumps Designs Systems for Maine Winter Performance
Modern cold-climate heat pumps absolutely work in Maine winters.
They provide steady, efficient heating through the vast majority of the season. During extreme cold events, properly designed systems either continue operating effectively or take advantage of the supplemental trading heating system if configured to do so.
The difference between success and frustration is not the technology, but proper design, sizing, and installation.
At Royal River Heat Pumps, we exclusively install residential heat pump systems in Freeport and the surrounding coastal region, from Kennebunkport to Boothbay Harbor. We’ve installed thousands of heat pumps in Maine since 2013. Visit our Testimonials page to hear from the many Mainers who love their heat pumps and rely on them all winter long.
