Heat Kits for Central Ducted Heat Pump Systems: What They Do and When They’re Needed

Central ducted heat pump systems are an efficient way to handle year-round heating and cooling, but there are conditions where supplemental electric heat becomes important. That’s where heat kits come in.

Heat kits are electric resistance heaters designed to integrate directly into compatible central ducted systems from MRCOOL, providing additional heating capacity when outdoor temperatures drop or when the system enters defrost mode.

What Is a Heat Kit?

A heat kit is an add-on electric heating module that installs inside a central ducted air handler. Unlike a heat pump—which moves heat from outdoors to indoors—a heat kit generates heat directly using electricity.

This makes heat kits especially valuable when:

• Outdoor temperatures are too low for a heat pump to operate at peak efficiency

• The system temporarily switches to defrost mode

• Additional heating capacity is needed during extreme cold snaps

In normal operation, the heat pump does the majority of the work. The heat kit only activates when needed.

Why Heat Kits Matter in Cold Weather

Heat pumps are highly efficient, but their output naturally decreases as outdoor temperatures fall. In colder climates—or during sudden temperature drops—this can lead to longer run times or reduced comfort.

Heat kits help by:

• Supplementing heating output when the heat pump alone isn’t enough

• Maintaining consistent indoor temperatures during extreme cold

• Providing heat during defrost cycles, when the system briefly stops heating to clear frost from the outdoor unit

The result is a more stable and reliable heating experience without relying on fossil fuels.

Heat Kits vs. Heat Pumps: How They Work Together

It’s important to understand that a heat kit does not replace a heat pump. Instead, the two work together as part of a complete heating system.

• Heat pump: Primary source of heating and cooling

• Heat kit: Secondary, electric backup that activates only when necessary

This combination allows homeowners to benefit from the efficiency of a heat pump while still having dependable heat in demanding conditions.

Are Heat Kits Always Running?

No. Heat kits are not constantly active.

They are controlled automatically by the system and typically engage only when:

• Outdoor temperatures fall below a set threshold

• The heat pump cannot maintain the desired indoor temperature

• The system is in defrost mode

This ensures energy is used efficiently while still prioritizing comfort.

Who Should Consider Adding a Heat Kit?

Heat kits are commonly used in:

• Colder or mixed-climate regions

• Homes relying entirely on electric heating

• Systems where consistent winter comfort is a priority

Even in milder climates, some homeowners choose heat kits as a peace-of-mind backup, especially for overnight heating or during rare cold snaps.

Compatibility with MRCOOL Central Ducted Systems

Heat kits offered in this category are designed to work with compatible MRCOOL central ducted heat pump systems. Proper sizing and compatibility depend on the specific air handler and system configuration.

While we do not provide installation services or installation advice, detailed compatibility information and installation documentation are available directly from MRCOOL, and licensed HVAC professionals can help determine the correct setup for a specific application.

A Reliable Way to Extend Heating Performance

When paired with a central ducted heat pump, a heat kit adds an extra layer of reliability - especially when temperatures push systems to their limits.

For homeowners looking to maintain comfort during colder conditions without sacrificing the efficiency of a heat pump system, heat kits provide a proven and practical solution.