Why are Certain Rooms in My Home Hotter than Others in the Summer Even After Replacing My AC System or Adding Insulation?

We get a lot of calls from homeowners that find themselves at a loss after trying for years to fix their hot rooms in their Phoenix Metropolitan area homes, even after replacing their AC systems, ductwork or adding insulation. So why are rooms still hot in homes even after doing all this work?

Well, a home needs to work as a system in order to function properly and provide even temperatures and comfort throughout the home. When one part of the system is thrown off or doesn’t work correctly, the entire system breaks down. 

Here are a few possible explanations as to why you could be dealing with hot rooms even after trying to balance the temperatures in your Phoenix home for years:

  1. Inadequate Airflow: Even if your AC system is new or your home is well-insulated, there may be areas of your home where the airflow is restricted or inadequate. This could be due to closed or blocked vents, kinked ducts, holes in the ducts resulting in duct leakage, improperly sized ducts, dirty air filters, or other other problems with the ductwork. Think of the ductwork in your attic as the arteries of the AC system. If your arteries in your body are blocked, kinked, shrunk down or leaking, your health will be affected. The same concept applies with ductwork.  If the air is not flowing properly, certain rooms may feel warmer than others and the overall health of a home will be compromised.
  2. Poorly Installed Insulation: While adding insulation can help regulate the temperature in your home, it’s possible that some areas may still be poorly insulated. This could be due to inadequate insulation in the ceilings, walls, or gaps and cracks in the insulation that are present that allow air to leak in or out. These areas may be more prone to heat gain or loss. For insulation to function correctly, it absolutely needs to be in continuous contact with another surface – which is often not the case. For example, if you have misaligned insulation on the attic flat, such as (misaligned fiberglass batts) and you just have a contractor blow more insulation over the top of the misaligned batting, the fiberglass insulation on the bottom still has gaps and voids. This means that even if you blow a nice, thick layer of insulation over the top of the misaligned batting, your rooms will still be hot and your energy bills will still be high. Proper air sealing and insulation alignment is a must to ensure.
  3. Home Design: The layout and design of your home can also impact how warm certain rooms feel. For example, rooms on the upper floors or above the garage can be hotter than rooms on the ground floor. This can be caused due to the garage being poorly and improperly insulated, heating up the room from the floor since the floor of the upstairs room over the garage needs to be insulated correctly from the garage ceiling. We rarely see upstairs bedrooms that are over the garage properly insulated.
  4. Size of AC Unit: If your AC system is too small for your home, it may struggle to keep up with the demand for cooling, leading to hot spots in certain rooms. Similarly, if your AC system is too large, which is quite often the case in Phoenix, it may cycle on and off frequently, which can create temperature imbalances throughout your home, not to mention the wear and tear on the AC compressor. The only way to determine if your AC system is properly sized for your home is to do a heat load calculation. Just keep in mind that bigger is NOT always better when it comes to heating and air conditioning as a bigger system that is not sized correctly uses more energy to operate and can cause all sorts of issues down the line.
  5. Solar Heat Gain: Rooms that receive more direct sunlight during the day may be hotter than other rooms, even with adequate insulation and a properly functioning AC system. This is because solar heat gain can raise the temperature of the air in the room, making it feel warmer. In order to fix this, more air must be distributed to the rooms – but you should never just “tap” into an existing duct system as the ducts need to be sized correctly for each room.

The bottom line is that you can replace the ducts, AC, or insulation but if the AC system or ducts are not sized or installed correctly, a home will be thrown off and cause hot rooms and imbalance temperatures throughout your Phoenix, Scottsdale, or Mesa home. 

We run into homes often that have work done on them only to find out the insulation, ducts or AC system weren’t installed properly, leaving them with the same issues they paid to fix. 

We are here for you if you have questions or need some help trying to figure out what’s going on in your home – give us a call at 480-839-0082 and we’d be happy to help answer all of your HVAC, ductwork, air quality and insulation questions!