Uneven Heating and Cooling Troubleshooting for Two-Story Homes

A man adjusting a thermostat on a white wall.

It's not uncommon for a two-story home to experience uneven cooling or heating problems. Even the best HVAC systems can wear down over time and lose their ability to evenly distribute warm and cool air throughout the home. If you notice uneven temperatures in your home, follow this troubleshooting guide to get your system back on track.

Air Vent Maintenance

A man changing a vent filter in a wall.

Check for any air vents that are clogged with dirt and debris. Vents cannot circulate air if they clogged or blocked by large pieces of furniture. You can clean the vents with a vacuum attachment. If you have an area of the home that is warmer or cooler than other rooms, closing one vent in the room will help push air to other parts of the home, especially the second floor. Just remember to keep at least one vent in the room open to help balance things out.

Zoning System

Having only one thermostat in a two-story home is another culprit for uneven temperature swings. It takes more time to heat two stories, so the thermostat on the first floor will sometimes shut off before the entire house is properly cooled or heated. Remedy this problem by adding a second thermostat to the upper floor. This will allow the system to remain on until all areas of the home are at the same temperature. You may need to add more than two thermostats, depending on the size and layout of your home.

Attic Insulation

Measuring pink insulation with a ruler.

Rooms on the second floor will not properly heat or cool if the attic is not well insulated. The warm air in the upper levels will escape through the attic, causing an uneven distribution in other areas of the home. Inspect the attic for good insulation by looking at the floor joists. If you can easily spot the joists, then the attic needs more insulation. Fortunately, adding more insulation is an easy project that will save you money in the long run.

Circulating Air

Check the main thermostat and make sure the fan is set to “on” instead of “auto.” This will ensure that the fan continues to circulate air even when the system is turned off. If the fan is on auto, then it will only turn on in conjunction with the cooling and heating units. The only downside to keeping the fan on all the time is that it will use more electricity. You can also run the fan for longer periods during the day and shut it off manually to conserve energy.

Inspect Ducting

An hvac duct.

Leaky ducts can put an extra load on your home’s HVAC system. Even small leaks will make your system run harder, which can lead to other problems down the road. Check the ducting for any major holes or tears, especially along the seams. Replace any units that are badly damaged and repair minor leaks with duct tape. It's also a good idea to make sure the duct work has been properly sealed and is the right size for your home.

HVAC System Requirements

If the air vents and ducting are in good condition and the attic is properly insulated, make sure your HVAC system is rated to handle the size of your home. If your home is too big for the system, then you might need to replace it with a larger model. This, of course, is the most expensive repair in this guide and should only be considered once everything else has been ruled out. If you replace the entire system, consider adding a more energy efficient model that capitalizes on the latest technologies in heating and cooling.