Your HVAC system should heat and cool your house evenly so that the temperature is fairly consistent in every room. It’s common for the basement to sometimes be slightly cooler and for the top level to be a bit warmer. Rooms with large south-facing and west-facing windows and/or skylights also tend to be warmer in the afternoon because of heat gain from the sunlight. If you frequently have major temperature differences in various parts of the house, it usually means that your HVAC system isn’t circulating air evenly. Let’s look at the various issues that can result in noticeable hot and cold spots in a house and what options you have for overcoming them.
Undersized or Oversized HVAC System
One issue that almost always causes hot and cold spots is if the HVAC system is too small or too large for the house. An undersized system just doesn’t produce enough heating/cooling to supply every room, resulting in the rooms that are furthest away from the system often never getting fully heated or cooled. Oversized systems have a tendency to short cycle, which means they only run for 10 minutes or less. This creates the same type of issue, as the system doesn’t stay on long enough to fully heat/cool every room. Unfortunately, the only solution, if your HVAC system isn’t the proper size, is to replace it.
Undersized, Oversized or Poorly Designed Ductwork
Many homes have issues with hot and cold spots because their ductwork is undersized, oversized or poorly designed. Undersized ducts result in the air the HVAC system produces encountering increased resistance, and this resistance makes it more difficult for the blower to move air throughout the entire duct system. Oversized ductwork also interferes with proper airflow, usually resulting in the airflow coming out of the vents near the end of the duct branches being extremely weak.
Ideally, most of the duct should run in straight lines with as few bends as possible. The more bends there are, the more resistance the air encounters. The return and supply sides of the duct system also need to be equally sized so that the volume of incoming and outgoing air is balanced. If the return ductwork is smaller, the HVAC system won’t put out as much heating/cooling as it was designed to. If the supply side is smaller, air continually builds up in the ducts. This creates increased pressure, which leads to more resistance and weaker airflow in some rooms. The only way to overcome any of these issues is to have some or all of the ductwork rebuilt or totally replaced.
Ductwork Leaks
Leaky ductwork can also create major issues with hot and cold spots at different times of the year. One or two small leaks typically don’t make a noticeable difference, but multiple larger leaks definitely can. Holes, cracks and gaps in any of the ducts allow much of the hot or cool air to escape into other parts of the house, resulting in little to no air flowing out of the vents further along the duct. This leads to the rooms that the vents supply frequently being cooler in winter and hotter in summer. Having one of our HVAC technicians inspect and reseal your ductwork will eliminate the issue. It will also lower your energy bills by enabling your HVAC system to work more efficiently.
Dirty Ducts
Dirty ductwork is another problem that plagues many homes, simply because most homeowners rarely, if ever, have their ducts professionally cleaned. Dust, lint, hair, and other particles continually collect in air ducts over time. This leads to piles of debris forming that cause the air to encounter more resistance and block it from smoothly flowing through the ducts. Scheduling professional duct cleaning is an easy and relatively inexpensive way to improve both airflow and indoor air quality.
Your ducts should be cleaned every three to five years. If you notice that your home is starting to be dustier than usual or that your vent covers frequently get clogged with debris, it’s a sure sign that your ducts are fairly dirty.
Closed or Obstructed Vents
With energy costs continuing to rise, most homeowners are looking for ways to save on their heating and cooling bills. One thing that many people do is close the vents in unoccupied rooms and parts of the house that are rarely used. The thought behind this is that it allows the HVAC system to heat or cool the other parts of the house faster. While the theory seems sound, closed vents create similar issues to what you get if your ductwork isn’t properly sized.
Closed vents caused conditioned air to get trapped in some of the supply ducts, which throws off the balance of incoming and outgoing airflow. This again creates additional pressure and airflow resistance, preventing the HVAC system from evenly circulating air through all of the supply ducts. By keeping all of your vents open and making sure that they’re not clogged or obstructed by furniture, your HVAC system will operate more evenly and also more efficiently.
Clogged Air Filter
If you’ve recently started noticing more issues with hot and cold spots, it could just be a sign that the HVAC air filter is starting to get clogged and should be replaced. A clogged filter restricts the incoming airflow, leading to the HVAC system putting out less hot or cool air. This again results in less air coming out of the vents that are furthest away from the system. The best way to avoid this problem is to check the air filter monthly and replace it at least every three months. If you have indoor pets or you use a higher-efficiency filter, you may need to replace it more frequently.
Lack of Zoning
Larger homes are often prone to hot and cold spots even when none of the other issues we just mentioned are present. It’s especially common in a multi-story house to have a significant difference in temperature between the basement and the top floor. You’ll also often encounter issues with the south side of a larger house being noticeably warmer than the north side whenever the sun is shining during the afternoon. Upgrading to a zoned HVAC system is the best way to overcome these problems and ensure that every part of your house stays exactly as warm or cool as you want.
A zoned HVAC system has multiple thermostats, and each thermostat is responsible for controlling the temperature for the part of the house it’s in. Metal dampers in the ductwork automatically open and close as needed to allow air to flow to each zone or block the airflow off. This ensures that each zone should always remain close to whatever temperature its thermostat is set to. There may still be times when the HVAC system is heating or cooling every zone, but the damper for each zone will close to block air from continuing to flow as soon as the zone reaches the correct temperature.
At Precision Heating & Air, our family-owned and -operated company has more than 40 years of experience helping homeowners in Dallas, GA, and the surrounding areas with their heating and cooling needs. From thermostat installation and zoning controls to duct cleaning, maintenance and repairs, we have the solutions to ensure you enjoy effective HVAC performance and consistent temperatures throughout the year. To schedule an inspection and get help determining what’s causing hot and cold spots in your home, contact us today.
