The condesner unit of a ductless mini-split next to an air conditioner outside a home

The popularity of ductless mini-splits has risen in the US over the last decade. Sales grew 16% each year up to 2018 when they were close to hitting 15% of the overall US HVAC market, according to BuilderOnline.com.

Despite their growing popularity, there is some confusion about mini-splits and how they compare to traditional air conditioning.

For example, in a recent survey by PickHVAC.com, 87% of respondents were unclear about the difference between ductless mini-splits and standard split HVAC systems, and 38% hadn’t even heard of a mini-split.

It’s hardly surprising then that questions like, “are mini-splits safe?” come up quite often.

There are many benefits that ductless mini-splits have over standard central AC systems that use ductwork to distribute conditioned air around a building.

This article will focus on the safety benefits of choosing a mini-split for your home, so read on if you’d like to learn more.

Are Ductless Mini-Splits Safer than Standard Central AC?

Ductless mini-splits are as safe, if not safer than traditional ducted central AC. Ducts can develop leaks, sometimes drawing in dirty or contaminated air, adversely impacting indoor air quality. Ductless mini-splits don’t use ducts and thus eliminate this risk.

The risks are freon leaks (which can also happen with central AC), reduced air quality, and potential short cycling. However, this is one of those cases where the rewards far outweigh the risks!

Mini-splits provide excellent levels of comfort and convenience and can be installed as part of a retrofit with minimal disruption to the fabric of the existing building.

Safety Benefits of a Ductless Mini-Split System

These heat pumps several primary safety benefits. Let’s consider the advantages they can bring to your home.

Mini-Splits and Air Quality

What could be more critical to your health and safety than the very air you breathe?

Well, ductless mini-splits have a distinct advantage over central AC when it comes to air quality risks because the ducts themselves in an AC system can be responsible for allowing dirty air into your home.

If a leak develops in the ducting, perhaps from damage or a duct becoming disconnected, dirty air from an attic or crawlspace can be drawn into the system.

Ducting near the ceiling reinforced with metallic tape to cover leakage

The most significant risks in terms of air quality are natural gas and carbon monoxide, which we’ll discuss below. 

Mini-Splits Pose No Carbon Monoxide Risk

Carbon monoxide is a toxic gas that can be released from combustion equipment. If this happens within an enclosed space near open ductwork, it can travel along the ducts and enter your living areas via vents and registers.

Carbon monoxide is a silent killer. Completely odorless and colorless, there is no warning of its presence, making it particularly dangerous.

You can buy carbon monoxide alarms that detect minuscule levels of the gas and alert you before it’s too late, but if you have a ductless mini-split, you eliminate this risk altogether.

Mini-Splits Won’t Allow Natural Gas into Your Home

Another risk that ducted air conditioning could pose is the risk of a natural gas leak in an enclosed space next to open ducting.

As discussed, for carbon monoxide, ducts could act as a conduit for natural gas to enter your living space. Although exposure to low levels of natural gas is not harmful, prolonged exposure can affect your health, and if it displaces enough air, it can cause suffocation.

Natural gas is also highly flammable, and a leak can cause a flash fire or an explosion if severe enough.

The distinct “rotten eggs” smell gives an early warning of the presence of natural gas, which makes it slightly less pernicious than carbon monoxide, but it’s still not welcome in the home.

With a ductless mini-split, you can relax knowing that your system won’t serve as a pathway for natural gas to enter your living areas.

A homeowner sits on the couch in her living room, appearing satisfied while adjusting her mini-split evaporator with a remote control

Ductless Systems Lower the Risk of Mold

Mold can cause various health problems, including allergic reactions, rashes, and eye irritation, and in some cases, it can cause breathing problems.

Ducting used in central AC can provide the right conditions for mold to grow. Mold spreads through airborne spores and can form in ductwork when humidity causes water to accumulate. It can be challenging to remove, requiring harsh chemicals and mold growth inhibitors.

Cleaning is quite an involved process, which is better carried out by a professional using specialized equipment. You can read more about that in our article on duct cleaning.

A profession using a brush for air duct cleaning

You are far better off with a mini-split system, which does not use ducting and therefore has nowhere for the mold to establish itself.

Security Against Intruders

Mini-splits require only a tiny (2 or 3-inch) hole in the wall to allow the refrigerant lines and electricity to be run between the outdoor heat pump and the indoor head unit.

This characteristic means the integrity of the building is not weakened in any way, and there is no point of entry to attract intruders.

Compare this to a window-mounted AC unit, which police spokespeople have previously described as “a welcome mat for home burglars,” and it’s clear that a mini-split is far more secure.

The problem with window-mounted AC units is that they provide burglars with an easy means of entry to your home. In some cases, all they have to do is give a firm push, and the whole unit can give way, leaving a welcoming opening for the burglar to gain access.

A reflection in a mirror of a burglar with a flashlight in a home during nighttime

The accordion side panels to window-mounted AC units are another weak point that can leave your home vulnerable. You can take steps to minimize the risk, like reinforcing the side panels or adding additional screws through the top mounting rail into the window sash.

However, compared to a three-inch hole in the wall, which in any case is packed with filler to keep it airtight, a window-mounted AC will always be less secure, no matter how much you try to reinforce it.

Risks of a Ductless Mini-Split System

Although both ductless mini-splits and central air conditioners are safe to use, that doesn’t always mean that you’re free of risks. Here are some potential dangers to be aware of.

Refrigerant Leaks

Both mini-split systems and central air conditioners use refrigerant, also known as freon. 

In a mini-split, the liquid travels through the copper wiring or tubing that attaches the compressor and the indoor air-handling units. As a result, the temperature of the refrigerant may warm up only to cool back down as it cycles through.

The refrigerant is a big part of how your ductless system can produce cold air. Thus, you’re right to be concerned when freon begins leaking from it.

Refrigerant leaks are common, often stemming from flare connection issues. Perhaps the flare is too tight, it’s too small, or you’re using the wrong flare nut.

You can generally tell that your mini-split system is leaking refrigerant when it begins running noisily, hissing or jingling. In addition, your utility bills can increase as the efficiency of the mini-split takes a hit.

Most noticeably, the evaporator coils could freeze. This is because the lack of refrigerant caused by the leak prevents the absorption of heat by the evaporator coils. As a result, condensation builds up on the coils and causes them to freeze. 

Refrigerant leaks are not exclusive to ductless mini-split systems, of course. Your regular central AC can experience the same side effects of a leak, including frozen evaporator coils. 

Short Cycling 

The other potential issue is known as short cycling. This occurs when the head unit is installed incorrectly or too large for the zone it’s supposed to cool. 

A homeowner installing a wall-mounted mini-split air handler below the ceiling

Short cycling reduces a mini-split’s ability to remove humidity and can prevent the system from reaching the desired temperature. In other words, the unit’s efficiency suffers, and the energy benefits you get from a mini-split are nil.

This issue is unique to ductless HVAC systems but will not occur if you hire professional technicians to install the equipment. 

Final Thoughts on Mini-Splits’ Safety

Already accounting for nearly one-third of the overall HVAC market, mini-splits are set to increase their market share further as adoption continues to grow in the US.

These systems are just as safe to use as a regular central AC, facing issues like refrigerant leaks and reduced air quality. The short cycling that can occur is usually only due to faulty installation, which shouldn’t happen often.

In addition, they have the following advantages over regular AC:

  • The indoor and outdoor units are linked by refrigerant lines and electric cables that run through a small three-inch hole in the wall, which does not compromise the security of the building in any way.
  • Mini-splits eliminate the risk of dirty air, toxic carbon monoxide, or flammable natural gas entering your living areas and causing harm. 
  • Since they are ductless, these systems eliminate health risks caused by mold build-up in your home’s ductwork.

With the many advantages of a ductless mini-split system over central air conditioning, we think the choice is clear! 

If you would like to find out more about mini-splits, including how much they cost to install and run, please read our article on the subject here.

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