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A Home Energy Audit Can Help Set Up Your Mini Split for Peak Performance

One of the most valuable investments you can make in your home is a home energy audit, before you install a ductless mini split. Ductless mini splits are one of the most energy efficient ways to heat and cool with these heat pumps that don't require ductwork to distribute the conditioned air. Like all HVAC equipment, they perform best when they operate in an environment that's been optimized for energy efficiency.

Heat pumps move heat from one place to another to either heat or cool the space in which they operate. In the heating mode, the mini split takes it from the outside air, and in the summer, it takes the heat from your home and expels it outdoors. The systems will do so more efficiently if they're not constantly having to condition spaces that have air leaks or thermal losses due to inadequate insulation.

The role of a home energy audit

These audits are usually performed by licensed energy auditors or HVAC contractors. They involve testing your home for energy losses, whether through air leakage or thermal transfer. The blower door test plays a central role in the discovery process.

Thermographic equipment is often used with the blower door test to isolate the air leaks and inadequate insulation. It shows the thermal differences between your home and the air coming in. Colder temperatures show in the blue to green ranges and warmer ones show as yellow, orange or red.

How the Audit is Done

The blower door sits in an adjustable metal frame and has a powerful fan mounted at the bottom. It has a set of gauges that measures the changes in air pressure. After the technician readies your home or area for the test, he or she turns on the blower door. It pulls air from the area and as it does, the pressure drops. How fast it falls indicates the overall tightness of the building's shell. If the shell is tight, pressure falls quickly. If not, it takes a longer time to bring the pressure down.

With the fan running, the contractor or auditor walks through your home with the thermographic camera or device to see where temperatures differ. If you conduct the blower door test when temperatures are less than 15 degrees different from the outside, the auditor may ask you to heat or cool the space to make up for the lack of thermal variation inside and out.

The Audit Outcome

When the home energy audit is over, you'll get a full report on where your home has areas of greater thermal transfer, caused by no or inadequate insulation and where the gaps, cracks or crevices lie. In some cases, you may be able to plug the leaks and add more attic insulation to boost the efficiency of the mini split. In others, however, you may need the assistance of a contractor who specializes in insulation installation and air sealing.

Inadequate wall insulation can be hard to remedy yourself, but a contractor can use specialized equipment to insert expanding foam insulation or blown cellulose. Other issues that may require a pro are recessed lights that protrude into the attic or leaks around chimneys or flues (to reduce the risk of electrical and attic fires).

After the Audit

Once you've had the home energy audit done and corrected the energy deficiencies, you can move toward selecting the ductless mini split best suited for your home. The process involves:

  • Sizing the system using Manual J software, the industry standard for selecting the system. Mini splits are manufactured in increments of a half ton. Installing one too large or small interferes with your comfort and the system's performance.
  • Selecting the energy efficiency best suited for your climate. In warm areas, a system with a high SEER (seasonal energy efficiency ratio) will provide the most cooling comfort. In cold climates, one with a high HSPF (heating seasonal performance factor) will heat the space better.
  • Installing the equipment properly. The systems need to be installed for the most heating and cooling efficiency and installation will depend on the layout of your home or space and your climate.

To learn more about a home energy audit that will help you get the most from a ductless mini split, contact the Mitsubishi dealer closest to you, who'll be happy to help you with the process.

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