All air-conditioning uses the same outdoor components to produce the cold refrigerant that cools the air inside a home. The difference with a ductless AC system (see illustration) is where that air is cooled and how it's distributed.Central-air systems send refrigerant to a bulky central air handler that then blows cool air into the house through a network of ducts. Ductless systems pump refrigerant to compact indoor units within individual rooms. Each split AC unit operates like a miniature air handler, delivering cold air into its own zone only when it's needed.Because there are no ducts, these systems don't have the air leaks, heat gains, or pressure imbalances that can undermine the efficiency and comfort of a central-air setup. And installation is a snap.

1. Interior Wall Definition

Interior Wall Definition

In this video, This Old House plumbing and heating expert Richard Trethewey explains how the pros retrofit a compact cooling unit. Turn off the electricity to the circuit. Hold mounting bracket to the wall, level it, then mark the screw hole locations and where to bore a hole for the refrigeration lines, condensate discharge line and electrical cable.

It's far easier and faster to fish a narrow bundle of insulated refrigerant lines through a house than to retrofit bulky HVAC ducts. You're likely to save 30% of electricity by replacing window AC units with a ductless system. Coincidentally, that's also about how much cooling is typically lost in central-air systems, thanks to leaky, poorly insulated ductwork.What to Know About Ductless AC. Cost: A single-zone system with one indoor unit starts around $3,000, including installation.

A four-zone system costs about $12,000, installed. Installation: You'll need a pro to mount the indoor and outdoor units and connect the 2½-inch-wide bundle of refrigerant lines and electric cables.

Maintenance: The filter on each indoor unit should be removed and cleaned every month. Once a year, have a technician check refrigerant pressure and flush condensate lines. Noise: Indoor units have whisper-quiet squirrel-cage fans driven by long-life DC motors. Decibel ratings run at about 25, roughly the same as rustling leaves. Warranties: Coverage ranges from 5 to 12 years, but you can expect this sort of mechanical equipment to last 15 to 20 years before it needs to be replaced.

Rebates: A few utilities offer rebates for installing ductless AC systems. Many more incentives are available for heat-pump systems. To see whether you might be eligible, go to.Size MattersBeware of installers who size a split AC unit using a rule-of-thumb estimate. More often than not, the result is oversize equipment that's costly to operate and can't effectively reduce humidity levels. Instead, insist on a “Manual J” heat-load calculation.

It figures system size based on math and factors such as climate, insulation levels, and sun exposure. All cooling systems carry a Seasonal Energy Efficiency Ratio (SEER) rating, which compares cooling capacity with the amount of electricity used over the course of a typical cooling season. Ratings on today's systems range from 13 to 33 SEER. As the graph below shows, the higher the rating, the more you'll pay for your system, and the lower your electricity bills will be come summer. Kaspersky internet security licence key. To see what effect SEER ratings have on estimated operating costs in your area, go to the central AC life-cycle cost calculator at energystar.gov.

System prices come from. Based on a 1-ton system in St. Louis at 12 cents per kWh. Calculated from 1-ton pricingWhat's a Ton?In the parlance of air-conditioning, a ton is not a measure of weight; it's a measure of cooling capacity. One ton of cooling extracts 12,000 Btus per hour from a space. That's enough heat to melt 1 ton of ice within 24 hours, hence the connection between weight and comfort.

The capacity of ductless systems ranges from 3⁄4 to 4 tons. All indoor split AC units include mesh filters that collect dust. But some, such as Mitsubishi Electric's, also offer filters treated with enzymes, to break down allergens like pet dander and dust mites, as well as ceramic filters embedded with platinum catalysts that neutralize odors.Whole-House CoolingAt first, ductless systems were simple, single-room affairs, often installed as replacements for window air conditioners. But now some outdoor units, like the ones made by, have grown so powerful they can supply refrigerant to as many as nine separate indoor units. Amazingly, each unit in one of these “multi-split” systems still operates independently.

When it comes to customized zoning, this option is hard to top. Ductless systems can produce both hot and cold air if you get a heat pump for the outdoor unit. Its key component is a reversing valve, which switches the direction of refrigerant flow to suit the season.Install FAQs. Who does the work?

Manufacturer websites can pinpoint experienced installers in your area, and are a good place to start your search. Where should the outdoor unit go? It will perform best in a shady location—the north side of a house or under a deck—as long as there's enough clearance for airflow and maintenance. Where should the indoor units go? Wall-mounted units are easiest to install when located on an exterior wall near the outdoor unit.

It's more challenging to connect the refrigerant lines to units mounted on interior walls, but since those lines run as much as 165 feet in length, it's not impossible. How long does it take? A system with one wall-mounted unit can be installed in about 4 hours. Each additional unit adds another 2 hours.

Ducted and ceiling units are more time-consuming. Wireless controls: There's no need for a separate wall thermostat with ductless units—you regulate them with a line-of-sight remote. Some systems, such as (shown), have Wi-Fi links that put your smartphone in control no matter where you are.Variable-speed compressor: Also known as inverter-driven compressors, they calibrate refrigerant flow to precisely meet indoor cooling needs, putting an end to the uncomfortable up-and-down temperature swings of single- or two-speed units. Variable-speed compressors, like those from, also use less power and last far longer than their fixed-speed counterparts.Sensors: A built-in occupancy sensor, like the ones from, maximizes energy savings by ramping up the indoor unit when you enter the room and turning it down when you leave. All air-conditioning uses the same outdoor components to produce the cold refrigerant that cools the air inside a home.

The difference with a ductless AC system (see illustration) is where that air is cooled and how it's distributed.Central-air systems send refrigerant to a bulky central air handler that then blows cool air into the house through a network of ducts. Ductless systems pump refrigerant to compact indoor units within individual rooms.

Each split AC unit operates like a miniature air handler, delivering cold air into its own zone only when it's needed.Because there are no ducts, these systems don't have the air leaks, heat gains, or pressure imbalances that can undermine the efficiency and comfort of a central-air setup. And installation is a snap. It's far easier and faster to fish a narrow bundle of insulated refrigerant lines through a house than to retrofit bulky HVAC ducts. You're likely to save 30% of electricity by replacing window AC units with a ductless system. Coincidentally, that's also about how much cooling is typically lost in central-air systems, thanks to leaky, poorly insulated ductwork.What to Know About Ductless AC. Cost: A single-zone system with one indoor unit starts around $3,000, including installation.

A four-zone system costs about $12,000, installed. Installation: You'll need a pro to mount the indoor and outdoor units and connect the 2½-inch-wide bundle of refrigerant lines and electric cables. Maintenance: The filter on each indoor unit should be removed and cleaned every month. Once a year, have a technician check refrigerant pressure and flush condensate lines.

Noise: Indoor units have whisper-quiet squirrel-cage fans driven by long-life DC motors. Decibel ratings run at about 25, roughly the same as rustling leaves. Warranties: Coverage ranges from 5 to 12 years, but you can expect this sort of mechanical equipment to last 15 to 20 years before it needs to be replaced. Rebates: A few utilities offer rebates for installing ductless AC systems.

Many more incentives are available for heat-pump systems. To see whether you might be eligible, go to.Size MattersBeware of installers who size a split AC unit using a rule-of-thumb estimate. More often than not, the result is oversize equipment that's costly to operate and can't effectively reduce humidity levels.

Instead, insist on a “Manual J” heat-load calculation. It figures system size based on math and factors such as climate, insulation levels, and sun exposure.

All cooling systems carry a Seasonal Energy Efficiency Ratio (SEER) rating, which compares cooling capacity with the amount of electricity used over the course of a typical cooling season. Ratings on today's systems range from 13 to 33 SEER. As the graph below shows, the higher the rating, the more you'll pay for your system, and the lower your electricity bills will be come summer. To see what effect SEER ratings have on estimated operating costs in your area, go to the central AC life-cycle cost calculator at energystar.gov. System prices come from.

Based on a 1-ton system in St. Louis at 12 cents per kWh. Calculated from 1-ton pricingWhat's a Ton?In the parlance of air-conditioning, a ton is not a measure of weight; it's a measure of cooling capacity.

One ton of cooling extracts 12,000 Btus per hour from a space. That's enough heat to melt 1 ton of ice within 24 hours, hence the connection between weight and comfort. The capacity of ductless systems ranges from 3⁄4 to 4 tons. All indoor split AC units include mesh filters that collect dust.

But some, such as Mitsubishi Electric's, also offer filters treated with enzymes, to break down allergens like pet dander and dust mites, as well as ceramic filters embedded with platinum catalysts that neutralize odors.Whole-House CoolingAt first, ductless systems were simple, single-room affairs, often installed as replacements for window air conditioners. But now some outdoor units, like the ones made by, have grown so powerful they can supply refrigerant to as many as nine separate indoor units. Amazingly, each unit in one of these “multi-split” systems still operates independently. When it comes to customized zoning, this option is hard to top. Ductless systems can produce both hot and cold air if you get a heat pump for the outdoor unit. Its key component is a reversing valve, which switches the direction of refrigerant flow to suit the season.Install FAQs.

Who does the work? Manufacturer websites can pinpoint experienced installers in your area, and are a good place to start your search. Where should the outdoor unit go? It will perform best in a shady location—the north side of a house or under a deck—as long as there's enough clearance for airflow and maintenance.

Where should the indoor units go? Wall-mounted units are easiest to install when located on an exterior wall near the outdoor unit. It's more challenging to connect the refrigerant lines to units mounted on interior walls, but since those lines run as much as 165 feet in length, it's not impossible. How long does it take? A system with one wall-mounted unit can be installed in about 4 hours.

Each additional unit adds another 2 hours. Ducted and ceiling units are more time-consuming. Wireless controls: There's no need for a separate wall thermostat with ductless units—you regulate them with a line-of-sight remote. Some systems, such as (shown), have Wi-Fi links that put your smartphone in control no matter where you are.Variable-speed compressor: Also known as inverter-driven compressors, they calibrate refrigerant flow to precisely meet indoor cooling needs, putting an end to the uncomfortable up-and-down temperature swings of single- or two-speed units. Variable-speed compressors, like those from, also use less power and last far longer than their fixed-speed counterparts.Sensors: A built-in occupancy sensor, like the ones from, maximizes energy savings by ramping up the indoor unit when you enter the room and turning it down when you leave.

A ductless air conditioner can be the best option for cooling an older home or an addition built without the proper ductwork. And have limits and take up space, but a ductless air conditioner is installed directly on a wall or ceiling and operates as seamlessly as a central air conditioner system. InstallationRetrofitting a home to install central air conditioning can cost thousands of dollars. As you'd expect, a ductless unit is a fraction of that cost. There is no labor involved to run ductwork throughout a home. Instead, a mini-split ductless air conditioner consists of a compressor/condenser that is installed outdoors, but instead of it having a large cooling coil outside, each room is equipped with a small and quiet indoor fan and cooling unit, which is typically installed high on a wall near the ceiling or on the ceiling.A small hole is cut through the wall to run the refrigerant lines, condensate drain, power, and control cables to and from the central outdoor unit.

Most units are about seven inches deep and can be installed flush into a wall or ceiling.