While high-efficiency VRF heat pumps and ductless mini-splits have grown in popularity among homeowners to keep their families warm during the heating season, a major limitation is their lack of performance in subfreezing temperatures.

Because Heat pump mini-splits transfer heat into your home from outside air, they don’t work well in temperatures below 30-45 degrees Fahrenheit. They can be easily over-tasked when dealing with subfreezing temperatures, reducing the heat pumps’ efficiency, the very thing that makes them so desirable. This causes them to produce less heat than the room requires, affecting the comfort of the room.

Installing a King electric heater for supplemental heating is one of the best ways to address this dilemma. The result is a far more efficiency in terms of the overall system’s Heating Seasonal Performance Factor (HSPF).


VRF heat pumps and ductless mini-splits work by extracting heat from the outside air. These heat pumps require a backup system to supplement their heating ability when the outdoor temperature gets below a certain temperature.

As the outdoor temperature drops, the heating requirement of the house increases and the output of the heat pump decreases.

The balance point is when the temperature of the room’s heating requirement and the heat pump output match. Typically between 30-45 degrees Fahrenheit. For any temperatures below the balance point, supplemental heat will be required.

To locate the balance point, the heating requirement (BTUs/h) of the house and the heat pump output (BTUs/h) are plotted against the changes in outside temperature. The place where the home heating requirement and heat pump output lines cross is the balance point.

Take a look at the graph of the Balance Point.

Balance Point Graph


Simply put, most Heat Pumps in certain climates (below 30-45 degrees) need a supplemental heating source. Usually electric resistance heating in the form of Cove Heaters is an ideal solution.


Zone Based Heating

Since Cove heaters can be installed in every room and are controlled independently by a thermostat, you can easily heat only the areas in use or that are not being comfortably heated by the output of ductless mini-splits.

Efficient Heat

Cove heaters combine the quick comfort of radiant heat along with the sustained warmth of convection heat requiring a much lower temperature to achieve the same level of heat transfer compared to other options. As a result, the thermostat can be turned down in a room and the room will still maintain a comfortable environment at even lower money-saving temperature settings.

According to the United States Department of Energy, for every degree of temperature reduction below 70 degrees you save 3 percent, therefore, even reducing the temperature by 5 degrees will equal 15 percent savings.

Directional Warmth From Above

They are installed high on the wall, close to the ceiling, and heat the objects in a room in much the same way as the sun heats the earth and the air outside. As objects in the room become warm, the surrounding air picks up heat by conduction and the entire room maintains consistently comfortable.

Space Saving

Since alCOVE cover heaters are mounted near the ceiling, this saves valued space, eliminates furniture placement problems that is the typical head-ache of baseboard heaters. In addition, you feel warmer because the heat is delivered where you live—down towards the floor.

Safe Heat

Because alCOVE heaters are non-intrusive, tucked up high in a room’s alcove space, there is no concern of furniture, drapes or children coming in contact with the heating source. alCOVE products are engineered to keep safety in mind and operate at safer temperatures than baseboard heaters. Plus alCOVE heaters are safety tested by Underwriters Laboratories.

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Since 1958, King Electric has delivered American Made smart comfort solutions to businesses and families through industry innovation, building a legacy of trust, and delivering unparalleled reliability.

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