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white residential house with a mini-split air conditioner on the ground at the left corner. Snow covers the front yard.

Boston residents are no stranger to the fist-waving frustration ice can cause in the winter months. When the conditions are just right, it can cover your car, driveway, trees, and—if you’re a ductless mini-split owner—your outdoor unit.

With ice forming everywhere, you might assume it’s perfectly natural for your unit to have a few icicles attached to it. Although mini-splits do have some built-in resistance to these piercing temperatures, no piece of equipment is invincible.

To help Boston homeowners like you keep an eye out for potential problems, let’s take a look at why ice is forming on your ductless system and what you can do about it right away.

Why Ice Forms on Your Ductless Mini-Split System

Understanding how ductless heat pumps warm your home can make it easier to see why ice develops so easily. Instead of generating their own heat, these systems move heat by transferring warmer, outdoor air inside the home.

By evaporating refrigerant within its closed-loop system, a heat pump pulls heat from the air around the unit’s outside coil and releases it inside to heat the home.

As a result of this heat transfer, the temperature surrounding the heat pump decreases. As the air dips below the dew point, condensation develops on the coil through a process known as condensation heat transfer.

While condensation on your outdoor unit’s coil isn’t a bad thing in and of itself, you can blame the extreme Boston temperatures for causing problems. When temperatures reach freezing, this condensation can lead to the buildup of ice.

How Your Ductless Mini-Split Prevents Ice Buildup

Although your ductless system isn’t impervious to colder temperatures, it’s not a sitting duck either. Most ductless mini-splits are equipped with a defrost mode that is designed to prevent the buildup of ice. An internal thermostat monitors the outdoor coil’s temperature and automatically kickstarts the defrost cycle when it gets too cold.

When a system is in defrost mode, it’s operation switches from heating to cooling. During this process, the outdoor coil’s temperature increases. Ideally, this rise in temperature is enough to melt the ice away and prevent potential damage. Once the internal thermostat reads the coil at a warmer temperature, the heating cycle will resume.

If your unit isn’t defrosting efficiently, there are a number of potential causes. An inspector might find any one of the following issues:

  • Leaking refrigerant
  • Faulty wiring
  • Poorly installed fan
  • Damaged reversing valve
  • Problematic thermostat
  • Malfunctioning outdoor coil

Why Ice Can Be a Problem for Your Ductless Mini-Split System

If the unit’s defrost cycle malfunctions, ice can start causing a problem for your ductless system. As the ice slowly overtakes the coil, the unit will struggle to pull enough heat from the outdoor air.

Other parts will be negatively impacted too as the frost continues to spread. Too much ice can decrease the energy efficiency of your ductless mini-split because it has to use more energy to deliver warm air to your home. This inevitably leads to higher energy bills.

How You Can Keep Your Mini-Split from Freezing

Extreme cold can be a given for Boston residents, but a frozen heat pump doesn’t have to be. With the help of these 3 preventative measures, you can keep your system humming all season long.

Get a Routine Inspection

This is a preventative maintenance and inspections can help keep your ductless heat pump working properly during the winter months, including the components essential for the unit while it’s in defrost mode.

Keep an Eye Out for Ice

While you don’t have to check daily, it’s a good idea to take a peek at your outdoor unit when you get a chance to make sure a miniature iceberg isn’t forming. Catching this issue early can end up saving you on repairs while ensuring your home stays warm.

Call a Professional

If you do notice ice forming around your unit, it’s vital to contact a ductless HVAC professional in Boston. Attempting to fix the problem on your own can lead to more harm than good. With so many intricate parts, it’s best to leave this issue with experienced professionals.

Frosty System? Call Your Boston Ductless Mini-Split Experts

If you’re noticing icicles on the outdoor unit of your ductless mini-split or are interested in having one installed, reach out to New England Ductless today. As one of the leading providers of ductless systems in the Boston region, we’ll have your system up and running again in no time.

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