How Do Ductless Mini-Split Heat Pumps Work?

Zoned HVAC” and “mini splits” are terms often used when talking about ductless mini-split heat pumps, a type of heating and cooling system that is capable of conditioning the air without the use of ducts.

For homes without existing ductwork, ductless mini splits are often the best solution for those renovating or adding on to their homes. They’re usually the perfect solution in situations where it isn’t practical to install new duct systems or extend an existing one.

Even in homes with ductwork, mini-splits are often used in larger homes as they can potentially save you on both energy consumption and costs. Convenient and flexible, ductless mini-split heat pumps allow you to cool or heat only the rooms your family uses rather than the entire house. Each has its own thermostat, so everyone in your household will enjoy comfort without arguing over one central thermostat.

How Ductless Mini-Split Heat Pumps Work

Two primary parts make up the ductless mini-split system, including the indoor air handling unit, and an outdoor compressor/condenser.

Typically mounted high on a wall or suspended from the ceiling, the indoor unit directs conditioned (heated or cooled) air into your living space. Instead of a complicated duct system, a refrigerant line connects the indoor unit directly to an outdoor compressor. Suction tubing, power cable, and condensate drain lines connect the indoor unit to the outdoor unit in addition to the refrigerant line.

In most cases, there is a single outdoor unit that connects to several indoor air handling units. While all of the indoor units are controlled separately, it’s only necessary to use one outdoor unit to absorb or distribute heat, depending on whether you’re cooling or heating the air.

Traditional central air systems deliver conditioned air into your spaces by sending air from the indoor air handling unit through a complex series of ducts.

How HVAC Zones are Designed with Mini-Splits

A qualified HVAC technician will help create the zones, so your family enjoys the convenience and energy efficiency you expect from your units, delegating each indoor air handling unit to a specific room, zone, or area in your home.

In most cases it is possible to use four indoor air handling units with one outdoor unit, providing comfort to four rooms or “zones” within your home. How many indoor units you need depends on factors including the number of family members in your home, the amount of heating/cooling required, and your home’s size.

The flexibility is an advantage homeowners enjoy, as you could have an indoor air-handling unit installed on the ground-level floor of your home, the upstairs level, and in the garage making it possible for you to control these separate areas and increase energy efficiency.

Another advantage of a ductless mini-split over a traditional ducted system is that conditioned air can’t escape as it often does with a typical duct system. Cracks and gaps commonly found in ductwork can result in the loss of about 20 to 30% of conditioned air, compromising your comfort and increasing energy costs.

Do Ductless Mini-Splits Provide Cooling and Heating?

In a word, yes. However, it’s important to consider the differences between gas furnaces, boilers, and other traditional methods of heating compared to heat pumps.

How a Heat Pump Operates

Ductless mini-splits operate by connecting the indoor handling units to the outdoor compressor, much like traditional heat pumps operate. However, instead of transferring conditioned air into the spaces in your home via a network of ducts, the indoor air handler is installed directly into the zone, room, or area in your home where it will be used.

Heat pumps work using heat energy that already exists and is detected in the air by the refrigerant, unlike furnaces that generate their own heat. What about when it’s cold outside – how does a heat pump provide heat?

Traditional AC units remove heat from interior spaces and send it to the outdoor condensing unit. With a heat pump, the process works backward, transferring heat found in the outdoor environment to the indoors. Super cold refrigerant absorbs heat from the air outdoors, basically, the same way an air conditioner works. The 2nd Law of Thermodynamics holds that heat naturally flows from a warmer body to a colder body, therefore when the refrigerant is colder than the outdoor air, it can absorb heat energy. Heat can be absorbed by a heat pump when temperatures outdoors drop as low as -4°F. Quite remarkable!

That said, your heat pump will have to work harder when temperatures continue to drop. Many people find that as temperatures drop below freezing, it becomes more difficult to heat their homes using a heat pump system. Considering temperatures often drop below freezing during winter months in SE Michigan, you may want to think about having a backup heating system available.

Pros and Cons of Ductless Mini Split Systems

Like most other types of equipment, there are advantages and disadvantages of ductless mini-split heat pumps. If you have a large home and only use certain rooms or zones regularly, it may be a good option for you. Ductless mini-split systems are also ideal if you’re adding on a room or renovating a space where there is no existing ductwork.

Ductless mini-split heat pumps are not the right solution for everyone, although they do offer many advantages. For example, if your home has existing ductwork and is a single-level home, a traditional HVAC unit will likely serve your needs better.

Disadvantages of Ductless Mini-Splits

Initially costs more than some systems, but operating costs are lower
Professional installation is a must to ensure proper design and installation
Indoor units may not be visually pleasing to some people

One of the most significant disadvantages is that in some areas, it may be challenging to find a qualified HVAC contractor to install your ductless mini-split system and service it. If you live in Ann Arbor or surrounding cities in southeast Michigan, Haley Mechanical employs highly skilled contractors specializing in mini-split systems.

Advantages of Ductless Mini-Splits

  • Convenience, flexibility (each indoor unit is controlled with its own thermostat)
  • Small size, unobtrusive
  • Simple installation requires only 3-inch hole in the wall for the conduit
  • Energy and cost savings
  • No ductwork needed
  • More secure (intruders have easy access with window units)
  • Remote control
  • Modern, streamlined appearance
  • Longer lifespan
  • Customization options
  • Use for cooling and heating your home

By upgrading to a heat pump system, you may be eligible for rebates, tax credits, and other incentives.

Have questions or interested in learning more about ductless mini-split heat pumps and how this type of system could be the perfect solution for your needs? Give Haley Mechanical a call today.

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