High Velocity Air Conditioner – Everything To Know

Introduction To High Velocity Air Conditioning

High velocity air conditioning systems use a small-diameter duct system to deliver conditioned air to each room. The air is delivered at a higher velocity than traditional air conditioning systems, resulting in a more even temperature distribution and improved air flow.

New construction – high velocity air conditioning ducts lie on the group; note these ducts are much narrower than traditional AC ducts

The ducts require minimal installation space, making them ideal for tight spaces. High velocity air conditioning systems are more energy efficient than traditional systems, as they use less energy to move the air and reduce the amount of energy lost through ducts. Although they have a bad reputation of being noisy, studies show that the noise levels were perceived to be about the same compared to a traditional duct system.

A High Velocity Air Conditioner Runs Off Electricity

Most air conditioning systems run off electricity. However, just like you can get a natural gas, stand-by generator as an emergency electricity source for your home, you can also get natural gas powered air conditioners. They’re not too common. On a running cost basis, gas power might be a little cheaper because grid electricity is a mix of sources some of which is more expensive than natural gas. Recently, as of mid-2023, natural gas prices have risen all over the world due to shortages which has the effect of equalizing the costs of appliances run off these two energy sources.

Advantages And Disadvantages Of High Velocity AC

High velocity air conditioners provide many benefits over traditional air conditioning systems. They are more energy efficient and provide improved air flow, temperature distribution, and indoor air quality. They require less installation space, making them ideal for tight spaces.

Some potential drawbacks of high velocity air conditioning include the following:

High initial cost: High velocity air conditioning systems can be more expensive to install than other types of air conditioning systems, due to the specialized equipment and installation process.

Limited cooling capacity: A high velocity air conditioner may not be able to provide as much cooling as other types of air conditioning systems, especially in large or open spaces.

Noisy operation: Some people complain that high velocity air conditioning systems can be quite loud, due to the high velocity of the air being blown through the ducts. This can be disruptive to occupants of the building and may not be suitable for certain environments, such as hospitals or libraries. However, studies have shown the noise to be indistinguishable to occupants. In fact, read on below we found a study that directly compared noises.

Limited flexibility: High velocity air conditioning systems are designed to be installed in specific locations, and may not be able to be easily relocated or modified once installed. This can make them less flexible than other types of air conditioning systems.

Cost Comparison Of High Velocity AC vs Duct AC

 The cost of a high velocity air conditioning system can vary significantly depending on the size of the home, the type of system, and the installation costs. On average, however, a high velocity system will cost between 50% to 100% more than a traditional ducted system.

The installation costs for a high velocity system will be higher due to the need for specialized tools and training. However, the cost savings from improved efficiency and reduced maintenance costs will quickly offset the initial investment.

One benefit is that standard systems have very large equipment that take up space whereas the high velocity unit fits into a closet. One study below shows that the cost of the high velocity system is $15,000. However, much of the cost is labor so will vary greatly depending on where you live.

When switching to a more expensive system, there’ll be even greater impact from taking action on ways to control your cooling costs.

Does A High Velocity Air Conditioner Require Ducts?

Yes, high velocity air conditioners require ducts, although the ducts are much narrower than those used for traditional air conditioning systems. The narrower diameter ducts require less space, making them ideal for tight areas.

For example, traditional ducts might take up half a closet to pipe down from one floor to a lower floor. The high velocity ducts are so narrow that you can thread them through walls. Additionally, the high velocity air flow ensures that the temperature distribution is more even and the air flow is improved.

What’s the downside of threading them through narrow spaces? It’s harder to work in tight spaces and installation will take more time and expertise which incurs greater labor costs.

The diameter of the high velocity duct varies depending on the size of the system and the space it is being installed in. Generally, the smaller the space, the smaller the diameter of the duct. For a typical residential application, the diameter of the duct may range from 2-5 inches (5-13 cm) in diameter.  For a typical residential application, the diameter of a regular AC duct may range from 6-10 inches (15-25 cm) in diameter.

High Velocity Air Conditioning Vs Mini-Split

High velocity air conditioning and mini-split air conditioning are two different types of air conditioning systems. High velocity air conditioning uses small, flexible ducts to deliver cool air to different areas of a building, while mini-split air conditioning uses a system of indoor and outdoor units to provide cooling.

One key difference between the two types of air conditioning is the size of the equipment. High velocity air conditioning systems use small, compact units that can be easily installed in a variety of locations, while mini-split systems require larger, outdoor units that are typically installed on the exterior of a building.

Another difference is the way in which the systems distribute cool air. High velocity air conditioning uses small, flexible ducts to deliver cool air directly to individual rooms or areas, while mini-split systems use a series of indoor and outdoor units to cool the air, which is then distributed through the building via a system of ducts.

Overall, the choice between high velocity air conditioning and mini-split air conditioning will depend on your specific needs and the layout of your building. High velocity air conditioning may be a good option if you need a compact, easily installed system, while mini-split air conditioning may be better suited to larger buildings or buildings with complex HVAC requirements.

A Systematic Comparison Of A High Velocity AC Vs Conventional AC

Study #1: Introduction

In 2015 an experiment was carried out the IBACOS research team in Denver Colorado comparing a high velocity air conditioning system to a conventional air conditioning system in two townhouses, both three stories each.

IBACOS (Integrated Building and Construction Solutions) is a consulting firm that specializes in providing comprehensive solutions to the building and construction industry. IBACOS helps clients make informed decisions and increase productivity, while reducing risk and cost.

Conducting the study in the same city, over the same duration, in very similar houses, provides for the best type of comparison.

Study #1 Showed Where The High Velocity Air Conditioner Did Better

In the IBACOS study, they found high velocity air conditioning systems offer improved air flow and temperature distribution compared to conventional ducted systems. They are more energy efficient, require less installation space, are quieter, and provide better indoor air quality.

The improved air flow and temperature distribution is inferred from the measurements. Below in the chart, the temperature difference between rooms is plotted over time after the ACs are switched on. The high velocity system showed a 0 to 3 degree F difference that was constant over 8 hours. The conventional system showed a 3 to 7 degree F difference, which is higher.

The high velocity systems are more cost-effective and require less maintenance. In comparison to conventional systems, high velocity systems offer more uniform temperature distribution between rooms, are easier to balance, and provide adequate temperatures on both the top and bottom floors. A chart of the room temperature variation over time below shows that the high velocity temperature variation (purple) was less than the conventional (red).

Conventional AC (B; red) and High Velocity AC (A; purple) shows the high velocity system has less room-to-room variation and drift over time

The total cost of the high velocity system was $15,000, compared to the standard system at $7,000. Again, we see the high velocity ends up being more expensive to install.

Caveats? This was a limited comparison of two houses and more data would be needed to gain confidence in the conclusions.

Study #2: Introduction

In 2010, the same team embarked on an assessment in a newly built, unoccupied test house situated in Pittsburgh, Pennsylvania. The focus of their research was to examine the performance of a commercially available high-velocity small-diameter air distribution system.

The team evaluated how this system managed room-to-room cooling and heating loads, adhering to the Air Conditioning Contractors of America (ACCA) Manual RS criteria for thermal uniformity and the ASHRAE Standard 55-2010 criteria for temperature variation over time. The main impetus behind utilizing a small-diameter (2-inch) duct system was to streamline the installation process of ductwork inside the conditioned space, and thereby potentially revolutionizing traditional practices.

Study #2 Showed Pros Vs Cons Of The High Velocity Air Conditioner

Pros of Small-Diameter Ductwork:

  1. Cost Savings: The material and installation costs for small-diameter ductwork are lower, making it an attractive option for builders aiming to reduce energy costs by bringing the ductwork into conditioned space.
  2. Aesthetically Pleasing: Small-diameter ductwork requires only a shallow bulkhead (dropped ceiling), which can be more aesthetically pleasing compared to traditional bulkheads.

Cons of Small-Diameter Ductwork:

  1. Register Placement: It’s essential to place the registers (outlets for heated or cooled air) accurately to avoid draft-related comfort issues. This requirement can complicate the installation process.
  2. Temperature Uniformity: Small-diameter systems may not maintain consistent temperatures between different rooms due to insufficient airflow and inability to adjust for variable solar gains.
  3. Fan Efficacy: Running small-diameter duct systems at high airflow rates can decrease fan efficiency. Therefore, it’s recommended to use system control to favor lower speed fan operation and minimize high-speed fan operation to maximize system performance.

High Velocity Vs Traditional Ducted AC Cost

Now that we’ve seen our first real estimates of cost, a few words are in order. High velocity air conditioning (HVAC) systems and traditional ducted air conditioning systems differ in several ways, each with its own set of advantages and disadvantages. These differences can affect the initial cost, operating costs, and overall energy efficiency of the systems. Here’s a general comparison:

Initial installation cost: High velocity AC systems are typically more expensive to install than traditional ducted systems. This is due to their specialized components, such as the smaller, more flexible ductwork, and the sound attenuation devices needed to reduce the noise generated by the high velocity air. If your home already has ductwork compatible with a traditional AC system, then this option could be less expensive upfront.

Retrofit cost: However, if you’re retrofitting an older home without existing ductwork, a high velocity AC system might be cheaper and easier to install because its ducts are smaller and more flexible, making them easier to fit within existing walls and ceilings. This could reduce labor and construction costs.

Operating costs: In terms of operating costs, high velocity systems are generally more energy-efficient due to their method of heat transfer and air circulation, leading to lower electricity bills over time. However, the actual savings depend on various factors like the efficiency of the specific models being compared, insulation of the house, and local electricity rates.

Maintenance costs: High velocity AC systems typically require specialized service, which can be more expensive than servicing traditional systems. However, because they’re designed to reduce humidity more effectively, they may offer better longevity and durability in humid climates, potentially reducing long-term maintenance costs.

Comfort and aesthetic considerations: Lastly, while not directly a cost issue, it’s worth noting that high velocity AC systems can be less conspicuous than traditional systems due to their smaller vents. They also deliver conditioned air more evenly, which can reduce hot or cold spots in your home. If you value these aspects, they could justify the potentially higher cost.

IBACOS Study Showed Where The High Velocity Air Conditioner Performed The Same

The IBACOS team showed that its not true that the high velocity is better than the conventional in every way. Both systems faced temperature issues on upper and lower floors (3rd and 1st respectively), but were found to be quiet and reliable. That is, there seemed to be no noise concerns with either one, although its worth noting that there are sound attenuation features in the high velocity ducts which are supposed to dampen the noise.

Companies That Make High Velocity Air Conditioners

These are manufacturers of AC systems, not installers. In order to put one into your home, and service it regularly, you will need to find a vendor. The best way to find a qualified vendor who has experience installing one of these is to ask the manufacturers themselves.

They have collected information on companies that have been using their products in a certified way. Below we list two examples:


Unico is a company that specializes in high velocity air conditioning systems. They are committed to providing their customers with the best air conditioning systems on the market. Their systems are innovative, energy efficient, and cost effective.

Unico also offers a variety of accessories and services to help their customers get the most out of their air conditioning systems. The company has been in business for over 50 years, and is dedicated to providing their customers with the best possible solutions for their air conditioning needs.


SpacePak is a leading manufacturer of high velocity air conditioning systems. They use a patented technology to deliver superior air flow and temperature distribution. The systems are designed to be energy efficient and require minimal installation space, making them ideal for tight spaces.

They are more cost effective than traditional systems, and provide improved indoor air quality and quieter operation. SpacePak is committed to providing the highest quality products, and their systems come with a 5-year warranty.

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