HVAC & DUCTWORK SPECIALISTS

What is the value of this QIV service to consumers?
Quality Installation Verification (QIV) testing ensures that your AC system is properly charged and has sufficient airflow. Using a COOL SMART Participating Contractor provides this benefit, which is not always performed by other HVAC technicians. The QIV service also helps the air conditioner operate more efficiently, meaning it's less expensive to operate and should last longer with fewer repairs.

My system is new - how can refrigerant charge be a problem?
Incorrect refrigerant charge is a common problem with residential air conditioning systems across the country. Contrary to most consumers' expectations, even newly installed air conditioning systems are often incorrectly charged.

In a recent New England study, air conditioning systems were tested for refrigerant level. Of the units tested, 31% were under-charged, while 28% were over-charged. This means only 41% - less than half - of all the units tested were properly charged. These results are consistent with other industry research in studies throughout the U.S.
If we are getting cool air, how bad can refrigerant charge problems be?

Incorrect charge significantly reduces the cooling capacity and energy efficiency of your unit and can also damage your system. If a unit is significantly undercharged, the compressor can overheat, causing it to burn up internally. Overcharging can flood the compressor with liquid refrigerant, causing the piston to catastrophically fail. In both cases, premature compressor failure is the likely result. In a recent test of air conditioners installed in Massachusetts, 14% of the units tested were severely over- or undercharged, which, as mentioned above, will likely cause early compressor failure if not detected and corrected.
If air is flowing out of the ducts, what could the airflow problem be?

Almost all air conditioners are designed to operate with between 350 and 400 cubic feet of air per minute flowing across the indoor coil of the unit for every ton (12,000 BTUH) of cooling capacity. When the airflow is greater than the manufacturer's recommendation, your system will have difficulty removing humidity from the air, leaving your house cool but humid. If the airflow is less than manufacturer's recommendations, your system will have to operate much longer to cool your house, and may even cause your system to ice up, leaving you with no air conditioning, and possibly a damaged compressor. Low airflow has the same effect as making your system smaller (less tons). In both cases, you will use more electricity to cool your house. QIV testing will verify that your system is operating at optimal capacity.
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Checking Airflow is Important!

“An efficient system starts with proper air flow. Low air flow = low capacity = energy wasted, compressing excess refrigerant. Cool the house, don't flood the compressor.”
-Senior manager, compressor manufacturer

Twelve different energy studies have been conducted on airflow in the past several years. Each study found that, on average, 70% of all home air conditioners have inadequate airflow. The average home air conditioner's airflow is 20% below the manufacturer's recommended level.

What steps are involved in the QIV process?

There are four basic steps. The report and instruments used will vary slightly depending on which type of verification tool the contractor uses.

1. Contractor phones in, or enters on a small computer, the test data about your air conditioning system.
2. Data analysis on-site or via phone generates results of refrigerant charge and airflow test data.
3. If tests show manufacturer's equipment specifications for charge and airflow are not met, the system provides feedback with suggested modifications; technician completes work*, retests unit and resubmits results.
4. Homeowner receives a report with information explaining test results.

*In many cases, obtaining correct airflow may require additional work, such as duct sealing or changes to the duct system, for which there may be additional costs. Even if there are extra costs, they are well worth the investment in system performance, equipment reliability and long-term energy savings.

What are some other indicators of a quality installation that I should look for in addition to refrigerant charge and airflow?

There are important elements to consider in achieving the best performance and reliability from your cooling or heating system. These may include proper system sizing, duct sealing, having work done by a NATE-certified contractor, insulating and tightening your home, and conducting combustion safety tests.

The Home Energy Rating System (HERS) Index is the INDUSTRY STANDARD by which a home's energy efficiency is measured. It’s also the NATIONALLY RECOGNIZED system for inspecting and calculating a home's energy performance.

What does a HERS Rating say about a house?

The HERS Index MEASURES A HOME’S ENERGY EFFICIENCY and there are a lot of great reasons to have a home energy assessment performed on your house.

It can tell you so much about the home you live in, like how efficiently it’s operating and where you can make modifications for greater energy savings. When you’re selling your home, a low HERS rating can command a higher resale price. And when you’re buying a home you can anticipate the costs of energy bills and efficiency upgrades.

How does the HERS Index work?

• A certified Home Energy Rater assesses the energy efficiency of a home, assigning it a relative performance score. The lower the number, the more energy efficient the home.
• The U.S. Department of Energy has determined that a typical resale home scores 130 on the HERS Index while a standard new home is awarded a rating of 100.
• A home with a HERS Index Score of 70 is 30% more energy efficient than a standard new home
• A home with a HERS Index Score of 130 is 30% less energy efficient than a standard new home

More on what the scores mean.

To calculate a home’s HERS Index Score, a certified RESNET home energy rater carries out an energy rating on your home and compares the data against a 'reference home' – an imaginary home of the same size and shape as the actual home, so your score is always relative to the size, shape and type of house you live in.

Some of the variables included in an energy rating are:

• All exterior walls (both above and below grade)
• Floors over unconditioned spaces (like garages or cellars)
• Ceilings and roofs
• Attics, foundations and crawlspaces
• Windows and doors, vents and ductwork
• HVAC systems, water heating system, and your thermostat.

Energy Losses and Their Costs

The purpose of a space-conditioning duct system is to convey heated or cooled air from the central furnace, heat pump, or air conditioner to the rooms where it is needed. Typical systems with ducts in attics or crawl spaces lose from 25% to 40% of the heat- ing or cooling energy that passes through them. In an era of increasing concern for energy efficiency, this is no longer acceptable.

Duct systems lose energy in two main ways: by air leakage through small cracks and seams and by conduction of heat through the duct wall. In addition, how the various systems and equipment interact has an effect on how well the ducts perform.

Air Leakage

Ducts lose energy when air leaks into or out of them. Sometimes this leakage is from holes in the ducts or from poorly connected duct joints. Even if the ducts are sealed, their operation can cause the house itself to leak more air because of differences in air pressure in various zones of the house.

Heat Conduction

Duct systems also lose energy when the warm or cool air they contain heats or cools the duct walls, which in turn heats or cools the air outside the ducts. In winter, ducts that are in an attic or vented crawl space that is nearly as cold as the outdoors lose this heat completely through the duct wall. If the ducts are in a basement, some of this lost heat may be recaptured as it warms the basement ceiling enough to reduce heat loss from the house. In summer, ducts gain heat from warm surrounding spaces, detracting from the air conditioner’s ability to cool the house.

Energy Savings

How much can you save by fixing a duct system or by installing it correctly in the first place? Let’s consider two benchmark cases, one in a cold climate (Chicago, Illinois) and the other in a hot, humid climate (Orlando, Florida). We’ll suppose that in each case the ducts are in a location typical of the region—a crawl space in Chicago, the attic in Florida—and that their size and insulation level are also typical. Furthermore, we’ll assume that they leak about as much as an average duct system.

With these parameters, ASHRAE Standard 152 3 can be used to calculate an expected average efficiency 4 of the duct system over an entire heating or cooling season. The results are as follows:

• Chicago house: 63% for heating, 83% for cooling

• Orlando house: 74% for heating, 65% for cooling.

Even within a given climate region, different homes and lifestyles will have different ratios of heating to cooling. However, as a benchmark, let us assume that in Chicago three-quarters of the energy requirement of the house is for heating, whereas in Orlando three-quarters is for cooling. The average duct efficiency will then be 67% in either location. In these typical cases, then, one-third of the energy given to the ducts is lost before it gets to the living space.

How much better can we do? A reasonable target for a duct retrofit would be to reduce the leakage by two-thirds—to 5% of the system fan flow on each side of the duct system—and increase the insulation level to R-8. This would result in the following duct efficiency levels:

• Chicago house: 81% for heating, 90% for cooling

• Orlando house: 86% for heating, 82% for cooling.

Using the same assumptions as above, this results in an average duct efficiency of 83% in either location.

With the original ducts, the equipment must provide 150 units of comfort in order to deliver 100 units of heating or cooling comfort to the house, because only two-thirds (67%) of that comfort makes it to the living space. With the repaired ducts, the equipment only needs to provide 120 units of comfort heating or cooling to get 100 units (83% of 120) into the house. Thus, the load on the equipment is reduced by 30 units, which is 20% of the original requirement. The cost of running the equipment also will be reduced by 20% over a heating or cooling season.

Relative Humidity

For climate control in buildings using HVAC systems, the key is to maintain the relative humidity at a comfortable range—low enough to be comfortable but high enough to avoid problems associated with very dry air.

When the temperature is high and the relative humidity is low, evaporation of water is rapid; soil dries, wet clothes hung on a line or rack dry quickly, and perspiration readily evaporates from the skin. Wooden furniture can shrink, causing the paint that covers these surfaces to fracture.

When the temperature is high and the relative humidity is high, evaporation of water is slow. When relative humidity approaches 100 percent, condensation can occur on surfaces, leading to problems with mold, corrosion, decay, and other moisture-related deterioration.

Certain production and technical processes and treatments in factories, laboratories, hospitals, and other facilities require specific relative humidity levels to be maintained using humidifiers, dehumidifiers and associated control systems.