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PTAC’s, Split Ductless Systems

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PTACs – Split Ductless Systems    By Betty Stephens

PTAC

The System
PTAC (packaged terminal systems) are also known as wall-split air conditioning systems or ductless systems. These PTAC systems which are frequently used in hotels have two separate units, the evaporative unit on the interior and the condensing unit on the exterior, with tubing passing through the wall and connecting them. This minimizes the interior system footprint and allows each room to be adjusted independently. The terminal package is the condensing unit located on the exterior and includes the compressor, condenser and condenser fan. The other terminal package is the evaporative unit located on the interior and handles air cooling and distribution. The internal evaporative unit includes the fan, expansion valve and evaporator coil.
PTAC system may be adapted to provide heating in cold weather, either directly by using an electric strip, gas or other heater, or by reversing the refrigerant flow to heat the interior and draw heat from the exterior air, converting the air conditioner into a heat pump.
Cost
While room air conditioning provides maximum flexibility, when used to cool many rooms at a time it is generally more expensive than central air conditioning. The primary disadvantage of ductless air conditioners is their cost. Such systems cost about $1,500 to $2,000 per ton of cooling capacity. This is about 30% more than central systems and may cost more than twice as much as window units of similar capacity.
An additional possible disadvantage that may increase net cost is that ductless systems may sometimes not be eligible for energy efficiency rebates offered by many electric utility companies as part of an incentive program to reduce summer cooling load on the electrical grid.
Efficiency
Ductless systems offer much higher efficiency (up to 27.1 SEER on some systems). Today’s brands include Aircon, Carrier, Daikin, Klimaire, LG, Mitsubishi, Sanyo, Fujitsu and YMGI.
Most ductless (split system) air conditioners still typically provide cooling to a single room or interior zone, just like a window air conditioner or PTAC; but more powerful outside units are becoming more and more available, supporting cooling of ever-more interior zones. Advantages of the ductless system include smaller size and flexibility for zoning or heating and cooling individual rooms. Flexible exterior hoses lead from the outside unit to the interior one(s); these are often enclosed with metal to look like common drainpipes from the roof. Those enclosures can be painted to match the color of the house.
If your goal is to create a quiet, comfort controlled room, or simply want to heat or cool an area without expensive ductwork, the ductless systems set a new standard for efficiency, great looks and comfort.

LG

Split Ductless System

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Split Ductless Systems
By Betty Stephens

splitductless diagram

A ductless air conditioner, also called a mini-split system, has two major components: a unit mounted on an inside wall that delivers cool air to the room and a unit mounted on the outside of the house. A pair of refrigerant lines that runs between the two systems one delivering electricity, the other one taking away condensate. The system also has thermostatic control and a variable quiet blower.

A split system has several advantages over a traditional window unit, first and foremost a thermostat that can keep the room at a constant, comfortable temperature instead of blasting on and off. Also, you don’t have to move a spilt system in and out of the window as the seasons change, and you don’t have the open-window security concerns of a moveable unit.

split ductless pieces

The rapid growth in recent years of duct-free air conditioning systems in the U.S. has been impressive. In a contracting unitary market, Ductless mini-split style systems are very common in major markets in Asia and Europe; they have not made significant penetration into the United States. In spite of the recent growth in the U.S. market, they still only represent around 5 percent of the U.S. unitary air conditioning market. This low penetration is probably due to the huge installed base of larger U.S.-style homes and businesses that already have ductwork in place.
Also, with the decline of new construction in the U.S., air conditioning purchases have been dominated by system replacements. And when an air conditioner needs to be replaced, it is usually easier and less expensive to continue using the existing ductwork and just replace the system with a traditional outdoor unit and indoor coil or air handler. Still, there are obviously some situations where ductless solutions make sense.

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Duct-free air conditioning provides good, economically sound solutions for smaller spaces which have no existing ductwork, and sales of these systems into U.S. applications will likely continue to grow to meet this demand.   The top concerns about duct-free systems are indoor airflow and air quality, ease of service/troubleshooting for technicians, higher-than-expected costs and some concerns about general appearance.

Components
A ductless mini split has three main components:
1. Outdoor condensing unit.
2. Indoor air handler/evaporator.
3. Conduit (3″-4″ diameter) housing a power cable, refrigerant tubing and a condensation drain.
The condenser is installed outside the home or structure and the conduit is run from the outdoor unit to individual offices, bedrooms, living rooms, computer/server rooms, basements, anywhere a controlled temperature is desired. Wall-mounted interior units are then placed in the desired spaces to cool or warm air as needed by means of refrigerant flowing between the outdoor and indoor units through tubing in the conduit.
Ductless systems manage environments individually with remote, handheld thermostats that control the temperature and air flow for each room. The heating or cooling is directed precisely where it’s needed, with less energy wasted to heat or cool empty areas. This capability also means temperatures can be set according to individual preference, with each room warmer or cooler than the other…
Common Applications
Over half of all the ductless systems installed were 1.5 hp and below (less than 22,000 Btuh) and the majority were 2 hp and below (less than 27,000 Btuh). Over two-thirds of all ductless installations are done with single evaporator models. Approximately 85 percent of all ductless systems are probably installed in commercial applications. The most common ductless mini-split applications in the U.S. would typically be those going into single space, commercial buildings and, to a lesser extent, some suitable ductless applications in small residential spaces such as those involving room additions or smaller, zoned apartments.
Issues
Units can be difficult to install, and it’s harder to find qualified professionals to do the work, as most are used to putting in duct systems. Second, Ductless split air conditioning units have leaks. There are leaks that occur, which are hard to fix. Third, it’s important to purchase the right sized unit, as a unit that is too small will not effectively cool the home and one that is too large will not remove enough moisture.
Cost
The price of ductless split air conditioner units range from around $1,500 to $5,000, depending on the BTU and overall efficiency. These units typically cost $1,500 to $2,000 per ton (12,000 BTU per hour). The overall cost of the unit will depend on the square footage that is needed to cool and the type of efficiency needed. Choosing to get a high-efficient air conditioner, such as a SEER (Seasonal Energy Efficiency Ratio) brand, costs more money for the actual system, but saves money on energy bills.

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