We all know that hot air rises, and that's a key factor in a common household HVAC problem: a second story that's hotter than the first floor. But it's far from the only factor, and a close examination of your home and HVAC system could help you alleviate this costly and uncomfortable summertime problem.
Let's take a look at some of the other major factors that can contribute to this issue:
Factor #1: Your Air Conditioner
Replacing your air conditioner is a major expense, but it's also an inevitability of home ownership. The average lifespan of a central air conditioning unit is 15 to 20 years, and with every year of use, your system loses a little of its efficiency. If your air conditioner is primed for replacement and you're sweltering in your second story, it could be that your system just can't keep up with demand anymore. You should have a thorough inspection from a licensed HVAC technician to be sure, though, because there are other potential causes.
If years of wear and tear aren't dragging your air conditioner down, there are still other ways in which your HVAC system could be the source of the problem. It could be related to overdue maintenance or a broken part, and it could even be that your air conditioner is too small for your home to begin with. If your installers didn't perform a proper load calculation prior to recommending a system for your home, you may have ended up with a undersized air conditioner.
Factor #2: Your Ductwork
The farther your air conditioner is from your second floor, the more ductwork it has to pass through to get there. And if that network of ducts is full of gaps and leaks, a lot of that cold air can get lost before it reaches your upstairs rooms.
Leaky ductwork can develop over a period of time, but it's most commonly related to substandard installation. Joints in ductwork should not only be bolted together securely, they should be sealed with a compound called mastic to ensure that treated air doesn't leak out. For maximum energy efficiency, they should also be insulated.
You may be able to inspect some portions of your ductwork yourself, particularly in your basement and attic. If you find leaks, sealing them with mastic is a simple DIY job. But the bigger problem is that leaks in your accessible ducts usually mean there are also leaks in the inaccessible ducts that run within your walls.
You can hire an HVAC technician to conduct a pressure test on your duct network to determine how leaky it is. If the test shows that you have significant leaks, that may be the source of your second-story stuffiness. Fortunately, you don't need to tear into your walls to fix it — modern techniques allow HVAC technicians to circulate a mist of liquid sealant throughout your ductwork to patch leaks from the inside.
Factor #3: Your Attic
On a hot summer afternoon, your attic can fill with superheated air. And if that happens, you'll need a strong barrier of insulation to keep that heat from radiating through the ceiling of your top floor.
Attic insulation is an important thermal barrier all year long. It keeps hot air in during the winter and out during the summer. But it can degrade over time, and it's possible that your attic doesn't have enough to begin with.
Insulation is measured in R-values, with higher R-values providing more thermal resistance. You can check the attic insulation R-value that is recommended for your climate zone using the U.S. Department of Energy's insulation map. If you're not sure what type of insulation you have, simply go up to your attic and check. If the attic floor is insulated with batts, you can probably read all the information you need on the paper backing. If you see loose-fill insulation, consult the Energy Department's insulation identification guide to try to determine the type.
You should also measure the thickness of the insulation. If you can see the joists in the attic floor, you can benefit from adding more insulation on top of what you already have. Warmer climate homes should have about 13 or 14 inches, while homes in colder climates could benefit from 16 to 18 inches or more, depending on the severity of winter temperatures.
In addition to blocking out attic heat, you should also have features to reduce it, such as rafter and soffit vents to encourage ventilation. You can make your attic ventilation even more powerful with an attic fan. It's usually a small job for a professional to install vents and a fan.
Finally, you can help block out even more heat with the right type of roof. Some new roofing materials are designed specifically to reflect heat, and there are even coatings that you can apply to an ordinary roof to make it more heat reflective. When shopping for these types of roofing materials, you can look for the federal ENERGY STAR label to identify the products that meet high energy efficiency standards.
Factor #4: Your Treeline
This isn't a factor with all homes, but if your multi-story home is surrounded by young trees, you could be getting lots of shade protection on your ground floor windows and lots of direct sunlight pouring in upstairs.
While you wait for those trees to grow, consider upgrading your window treatments on your upstairs windows and keeping them closed more often. Reflective shades, blackout curtains and heavy drapes can make a big difference in blocking out unwanted daytime heat.
Figuring out which one of these factors is affecting your comfort — or whether it's a combination of factors — is easier said than done. If you need help finding the answer and fixing the problem, reach out to your All Pro Heating and Cooling today.