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.

How Safe Are Mini Splits?

Ductless mini-splits are as safe, if not safer, than traditional ducted central AC.

Since these units are heat pumps, they effectively replace both your furnace and AC. Heat pumps are so energy efficient because they don’t create heat like a furnace does but rather transfer it.

This also means there are no open flames or hazardous gasses that could leak out.

Ducts can also develop leaks, sometimes drawing in dirty or contaminated air, adversely impacting indoor air quality.

The majority of mini splits are ductless, thus eliminating any issues associated with ductwork.

Mini splits do use refrigerant, so there is a risk of a leak where it escapes into the atmosphere. This is the case for all air conditioning systems.

While leaks are not good for the environment, they won’t cause harm to you or your family.

Let’s take a look at all of these in detail.

Safety Benefits of a Ductless Mini-Split System

Mini-Splits and Air Quality

Ducting near the ceiling reinforced with metallic tape to cover leakage
For some homeowners, ducts can be an eyesore that affects a home’s value.

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. Forced-air furnaces have sealed combustion chambers and failsafes to prevent CO from escaping.

However, if the furnace develops a crack in the heat exchanger, it could leak into your home.

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

If your home has a gas-fired furnace, water heater, or boiler, you must have a carbon monoxide detector in your home.

Mini splits do not have this risk. They find existing heat within the ambient air to provide your home with heat. There is no combustion involved.

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

Mini split systems are fully electric. Unless you use natural gas or LP for other equipment, you do not need to have it installed in your home.

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 deadly than carbon monoxide.

Still, it poses risks to pets and children who might be left alone and not know to get out before it’s too late.

A homeowner sits on the couch in her living room, appearing satisfied while adjusting her mini-split evaporator with a remote control
Rest easy and worry-free with ductless mini-splits!

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 sometimes 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.

Again, mini splits do not have these risks, simply because they do not utilize ductwork.

A profession using a brush for air duct cleaning
Duct cleaning is an expensive preventative measure that may discourage potential homeowners.

High Efficiency

Efficiency is probably the biggest advantage of the mini split system. Despite being a fully-electric system, they offer low monthly utility bills through the use of their own integrated smart technology.

These units are designed to provide maximum comfort while using the least amount of energy possible.

Using an inverter is one notable piece of technology that makes ductless mini-split systems highly efficient.

This technology converts high-voltage electricity into DC voltage, making it possible for these systems to operate using less power.

The inverter technology results in higher SEER ratings of over 30 for cooling and heating.

Also, ductless mini-splits incorporate variable-speed compressors. This means they can self-adjust their speed to run as much or as little as needed without consuming excessive power.

Precise Control Over a Home’s Comfort

Ductless mini-splits are one of the best options for zoning control at home. Most of these systems have multiple indoor units (also known as heads).

With the use of multiple air handlers, you can have one running while the others are off. This makes it easy to precisely control your home’s comfort.

The ability to control the system independently for a given room makes it suitable, especially if you have some rooms that you use more than others.

You can ensure that these rooms are at the optimal temperature needed for comfortable living.

The zoning control capacity will also help you save energy and, consequently, utility bills. This is the most common setup for heating and cooling larger homes and spaces using mini splits.

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.

In a mini-split, the liquid travels through the copper wiring or tubing that attaches to the compressor and the indoor air-handling units.

The refrigerant is a big part of how your ductless system can produce both heating and cooling.

Refrigerant leaks are something to be aware of. A leaking mini split is not going to harm you but it could harm your equipment.

Running on low refrigerant will most certainly damage the compressor if left alone.

The first sign of a leak is often a mini split that struggles to maintain the temperature setting.

If it is a big leak, you will likely see ice forming on the lineset outside, and perhaps even the coils.

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. 

If you think your mini split has a leak, make an appointment with an HVAC professional right away and do not run the system until it gets repaired or you could overheat the compressor and cause the entire unit to fail.

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
HVAC professionals can diagnose any problems your unit may be having especially those that may be a result of incorrect installation.

Short cycling reduces a mini-split’s ability to remove humidity and can prevent the system from reaching the desired temperature.

This is why you must hire professional technicians to install the equipment. 

Poor Air Filtration

Although ductless systems have air filters, these are not as powerful as the ones in ducted filtration systems. This means they are less effective in ridding a home of allergens, odors, and dust.

While you can use carbon inserts to enhance the system’s efficiency, these inserts require frequent replacements, which comes at a cost.

Mini split air filters should be cleaned every six weeks on average. You can do this easily by removing the filters from the access compartment and rinsing them off in the sink until clean.

Other Drawbacks Of Ductless Mini-Splits You Should Know

  • Initial upfront cost: Installing these systems for an entire home is a costly exercise. This is because you’ll have to install the heads in every room you want the temperature controlled.
  • Maintenance: These systems require regular maintenance from HVAC professionals. Often, a tuneup every couple of years will suffice but it is an expense to be mindful of.
  • Drainage: Ductless mini-splits collect moisture into condensate lines. The system can use gravity to run the condensate outside for draining. However, if that is not an option due to your home setup, you’ll be required to install a condensate pump, which adds to the cost and maintenance needs.

Sizing a Ductless Mini-Split System

If you decide to acquire a ductless mini-split system, here is a table to guide you in getting the right option for your home:

Your Home’s Square FootageBTUs Needed Per Hour
150 to 2506,000
250 to 3007,000
300 to 3508,000
350 to 4009,000
4000 to 45010,000
450 to 55012,000
550 to 70014,000
700 to 1,00018,000
1,000 to 1,20021,000
1,200 to 1,40023,000
1,400 to 1,50024,000
Table 1: Sizing ductless mini-splits. Data from Sylvane

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 if you hire a licensed professional to do the job.

All in all, their advantages outweigh their risk and none of their “risks” can harm you or your family if something were to go awry.

That cannot be said for most other types of HVAC systems. Even if your mini split develops a refrigerant leak, while not good for the environment, it will not harm you.

If you’re looking for a safe heating and cooling choice, mini splits are certainly one to consider.

Whether they are the best choice for your home will depend on a variety of other factors that you can discuss with your HVAC contractor.

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.

If you’re a light sleeper, then you’ll surely want to find out if they’re too loud for your bedroom! Check out our article on the noise levels on these ductless mini-splits.

We also recommend these twelve online stores to buy your ductless mini-splits for more savings and faster shipping!

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