The duct work system is responsible for distributing the conditioned and filtered air throughout your home and returning it back to your heating and cooling equipment. Properly installed duct work will maintain an even temperature throughout the home, have minimal air leakage, and produce a negligible amount of noise. On the other hand, a poorly installed duct system will lead to hot and cold spots, cause higher utility bills from efficiency loss, and be a noise nuisance. The materials used, the design, and the installation practices determine the quality of the duct work system.
Sheetmetal is without a doubt the best material…its durable, efficient, and quiet. However, this is very rarely used in the San Antonio residential market for a number of reasons including cost and framing designs. The majority of the market uses a combination of duct board and flex duct. These types of products work great if properly designed and installed, but something to think about is the different options within this product segment. Both duct board and flex duct are offered with different insulation values, and flex duct alone comes in a variety of specifications that affect the durability and efficiency. Be sure to know what products are being used and if they meet the local building codes.
How much air each room needs, the size of individual ducts, the type and size of supply and return grilles…are all design questions. It takes knowledge and experience to get it right, but most of the companies doing it right rely on the help of software. The starting point for every well-designed duct system is a Manual J (calculation to determine the heating and cooling loads of a home and individual rooms) and a Manual D (method used to determine the overall duct lay-out including the individual duct sizes). There are several industry approved software applications that help generate a Manual J and D, and ultimately a duct system “blueprint.” A contractor should be able to show you a detailed blueprint before ever installing a single duct.
The third leg of this barstool are the installation practices…how does part A connect to part B? This is the hardest component for a homeowner to evaluate. This involves all of the “little things” that a homeowner will never see…is the collar properly sealed, or is that back section that you can’t get to sealed? Of course, there are obvious indications as to the quality of the workmanship like the ducts being properly strapped up and the use of duct sealant around connections. A good contractor will be proud to show you their work and stand behind it with a warranty.
Just because you can’t see it doesn’t mean its not important. The most efficient air conditioning equipment will not fix a poor and leaky duct system. A properly installed duct system is a great investment for the health and comfort of your home.
Like most other products for your home, the technology for air conditioning systems has vastly improved over the last 10 years. The efficiency of systems has improved, thermostats have become smarter, and even the refrigerant has been updated to be more environmentally friendly. One change having the biggest impact on overall performance is the shift from single stage cooling (On or Off) to multi-stage cooling (2-stage all the way to true variable speed). The benefits behind having multiple cooling stages are higher efficiencies, better comfort and indoor air quality, and quieter operation.
Multi-stage equipment is able to take advantage of lower cooling demands by operating at lower stages. The lower stages use less electricity which makes the system more efficient in the summer, and in the winter if you have a heat pump system. SEER (Seasonal Energy Efficiency Ratio) and HSPF (Heating Seasonal Performance Factor) ratings are like your car’s MPG – the higher the number the greater the potential for savings. For example, Carrier’s Infinity Series heat pumps offer a range of efficiencies that reach as high as 20.5 SEER and 13 HSPF. To put this into perspective a basic single stage heat pump starts at 14 SEER and 8 HSPF.
The real reason why you pay a premium for multi-stage equipment is for the better comfort and indoor air quality. Not only does this equipment control the temperature in the home, but it also has the capability to control humidity. As outdoor conditions and demands inside the home change, the equipment makes adjustments to maintain your comfort levels. This allows the system to operate longer and steadier throughout the day, and constantly remove moisture from the air. Also, since the system operates longer it is pulling more air through the filters thereby removing more dust and debris.
Most manufacturers only offer multi-stage systems in their higher tier offerings. For example, Carrier’s 5 stage and variable speed systems are only offered in their Infinity platform. Higher tier equipment comes with sound dampening features like a compressor enclosure, and when you couple this with the quiet operation of the lower stages the result is a more peaceful home.
We are excited about helping Evolutionary Homes build the St. Jude Dream Home Giveaway house. This will be a beautiful home built in Cresta Bella in northwest San Antonio, TX. Tickets to win the home will be available this summer with proceeds going to St. Jude’s Hospital. We are humbled to do our small part and hope the winner enjoys the home and the AC system.
Before most people buy something new, especially for high ticket items, they will look at the ratings and measurements of the product. For a car someone might look at MPG, or the resolution if they are buying a new television. But how do you compare new air conditioning systems with so many different manufacturers and models?
After the type of system and correct size is determined, you can begin to make “apples to apples” comparisons. The first step is to determine how many stages or speeds does the system have. This is most applicable for the cooling mode if you are in South Texas. A single stage system is the most basic and affordable. It is either on or off and is controlled by the temperature in the home. A two stage system has a low and high cooling mode. The benefit for this type of system is humidity control, in other words, this system monitors both temperature and humidity to determine what stage to turn on. There are also five stage and “true” variable speed systems which improve upon the benefits of the two stage system. Basically, the more stages the better.
You should also become familiar with terms like SEER and EER. SEER stands for Seasonal Energy Efficiency Ratio, and EER stands for Energy Efficiency Ratio. There is an independent company that tests the systems under fixed conditions and applies the appropriate rating. Without getting too deep in the math behind SEER, it is a measurement of how efficiently a system cools over the course of the summer. So the higher the number the more efficient a system is. EER is a more direct measurement of how efficient a system operates when running at 100%, but less consideration should be given to this rating especially when looking at multi-stage equipment.
SEER and EER are important numbers and also determine utility rebates (utility companies like CPS and GVEC incentivize customers to upgrade their AC systems). The SEER range starts at 14 and can exceed 20 on some higher end systems. You should use your budget to maximize the efficiency rating and the number of stages, but be sure to have the duct work checked as well. Installing a 20 SEER variable speed system on a leaky, poorly designed duct system is like putting wooden wheels on a Ferrari.