Field Test of Integration Controls for Ductless Minisplit Heat Pumps in Minnesota

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Ductless minisplit heat pumps are a popular alternative to central air-source heat pump systems. Among other advantages, these systems make for a simple retrofit into homes with existing space heating systems. However, that creates a potential issue in coordinating two independent heating systems to take advantage of the increased efficiency without sacrificing comfort.

This project looked at how integration controls affect the efficiency and comfort of ductless minisplit heat pumps paired with existing electric-resistance heat. The project team installed heat pumps in three homes in the Twin Cities area and tracked energy use and temperatures. After the heat pumps were used for a while, we added controls to coordinate the two heating systems and monitored energy use and temperatures before and after adding the controls.

All three homes showed substantial energy-cost savings from installation of the mini-split systems and the systems were able to comfortably condition the indoor environment even under very cold conditions. In the field study, all three households were indifferent to the integration controls — largely because they never had to use the existing electric baseboard heat. For motivated households like these, integration controls are likely an unnecessary expense.

Report Prepared by: Scott Pigg
Project Team: Allie Cardiel, Dan Cautley, Andy Lick, Scott Pigg, Rebecca Sadler