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Man With Beanie and Sweater Freezing in His House

10 Mar 2023

Author: Jeff O'Hara

Just about anybody with a multi-story house will relate to this blog, as the seemingly impossible goal of balancing the temperature between our upstairs and downstairs areas. During the milder months of the year, it may not be as noticeable of a problem, but in the peak summer and winter months, the difference between your home’s upstairs and downstairs areas can vary greatly. 

Most people assume that a central heating and air conditioning system is all needed to heat and cool their home accurately and evenly. While that’s a fantastic setup for a fairytale, the real world poses challenges to our HVAC systems that make balancing the environment between the upper and lower floors of our homes during the different seasons. 

Why does this situation keep happening, and what can a homeowner do to achieve a better temperature balance between floors? Let’s dive deeply into what you can do about uneven home heating and cooling.

What Causes Uneven Heating or Cooling Between Floors? A Quick Science Lesson. 

You may remember your high school science teacher telling you that “heat rises”, which sort of helps in our explanation, but is also a bit misleading. 

The phenomenon that seemingly makes warm air rise and cold air sink is technically called thermodynamics, a branch of physics that deals with the relationships between heat and other forms of energy. The laws of thermodynamics deal with how energy transfers from one place to another, as well as from one form to another, and how the resultant heat corresponds to a particular amount of mechanical work. 

For our purposes, warm air rises when it is surrounded by colder air due to it being less dense, which allows the transfer of heat upward. This technically disproves the adage “heat rises”, as it’s not the actual heat energy that’s rising; it is the air that was heated by the energy that becomes less dense, allowing it to float above the cooler air.

Why Do I Have Uneven Temperatures Between Floors in the Summer?

Since most of our home’s entry points are located on the ground floor, there’s more opportunity for warm air to enter the lower level of the house. Leaving the garage door open on a hot summer day will raise the temperature of the ground floor by as much as 5° or 10° pretty quickly. Leaving your window blinds open where there is direct sunlight exposure can raise the temperature, as can repeatedly opening and closing entry doors. 

  • The Roof. The Roof. The Roof is 140° in Direct Summer Sunlight!

It’s not just a hot air assault from the ground floor that can cause drastically uneven temperature differences upstairs in the summer. Your roof is exposed to direct sunlight all day, creating temperatures as high as 140°F in your attic, which presents a challenge to your air conditioner. 

In fact, here in Houston and much of the south, homes are designed with higher ceilings than you would find up north in colder climates. The greater ceiling height allows for enough vertical air space for the warmest air to rise toward the ceiling, allowing it to remain cooler closer to the floor. 

  • Ambient Outdoor Light Raises the Temperature

Rooms that get a lot of direct sunlight are a joy during the fall and winter months but provide nothing but misery during the summer. Installing dark curtains and window blinds that can keep much sunlight from entering the home will also help balance temperatures. 

Why Do I Have Uneven Temperatures Between Floors in the Winter?

As we mentioned earlier in our paragraph about thermodynamics, warm air is less dense than cold air, which can also work against your HVAC system in the cooler months. All that heat in your attic during the summer is gone and replaced by the chilly winter air. Any air gaps between the attic and the living space will be literally sucking the warm air out of your living space to raise it high above the coldest air in the attic.

How Can I Balance My Upstairs and Downstairs Temperatures?

Prevent Outdoor Air from Getting into Your Home.

Check that the seals around your drop-down stairs that lead to the attic are still pliable and airtight. Many builders use the cheapest materials possible, and that includes the weather stripping around your attic entry. If the material has become dried out and brittle, you’ll need to replace it, which should take less than an hour or two for the handy homeowner. 

Older, single-pane windows are another potential cause for uneven heating or cooling, as the thin, untreated glass provides little in the way of thermal protection. Gaps in door frames are an open invitation to untreated outdoor air to come in and get comfortable. Replacing worn and weather-beaten windows with energy-efficient dual-panel models and sealing door frame gaps can pay up to 15% off monthly energy bills. 

Proper Insulation is Essential to Temperature Balance.

Ensuring that you have the proper type and amount of insulation installed in your attic will prove to be a big help in balancing upstairs and downstairs comfort during the summer months. A lack of proper insulation in the home’s exterior walls will also result in uneven cooling and heating, as outdoor air can occupy the space inside the wall, altering the indoor temperature.

Install an Exhaust Fan in the Attic.

When temperatures are at their highest in the summer, an exhaust fan in the attic can be extremely helpful in evacuating the trapped heat and humidity. With attic temperatures commonly exceeding 140° during the summer, an exhaust fan can lower that temperature by as much as 30° – 40°F, making your upper floor more comfortable and reducing the workload on your air conditioner. 

Inspect and Repair Leaky Ducts.

Most ductwork currently installed in homes is known in the HVAC industry as “Flex” –or flexible duct—which is made of an inner coil made of thin, flexible wire. The wire coil is covered with a layer of specialized plastic and an outer layer of insulation that keeps the treated air at the proper temperature and protects the plastic layer. 

Flex-duct isn’t the most durable product available for HVAC air transfer, but it is far less expensive than the alternative of custom steel and aluminum ducts. As flex-duct gets pulled across attics and stuffed into walls, there is a good chance of tearing the outer layer or for joints between ducts to work loose. 

Leaky ductwork will permit untreated air to enter your living spaces anytime the system runs, resulting in uneven temperatures and adding dust, fiberglass insulation particles, and any chemical fumes in the attic full access to your home. 

Change Air Filters and Get a Maintenance Service.

Dirty air filters are the bane of your HVAC system’s existence, and the solution to 80% of residential HVAC problems is simple maintenance. When did you last change the filter in your HVAC system, or had the refrigerant level checked? Do you know, with confidence, that your gas burner for your furnace is clean and ready to fire up on that first chilly morning of the season? 

Nick’s Air Conditioning will happily send one of our licensed and experienced HVAC technicians to your home for a maintenance visit. Our Nick’s AC Maintenance Service includes a 32-point inspection of your air conditioning system and an additional 20-point inspection of your furnace and heat exchanger. 

Try Using the “Fan Only” Setting on Your Thermostat.

Most homeowners have their HVAC thermostats programmed to only run the blower motor fan when either the heat or AC is operating. The time in between cycles gives the treated air the opportunity to settle high or low, depending on which mode your system is in. Allowing air to circulate around the house between cycles maintains a balance between the cooler and warmer air, triggering fewer “on” cycles and improving comfort. 

Your thermostat will have a switch for the fan, either physically on the panel or as a setting in your electronic thermostat app. Change the fan setting from “auto” to “on,” allowing the system’s fan to run regardless of whether the heat or AC is active. Running your central fan doesn’t use much energy and may lower energy usage because your HVAC system won’t need to cycle as often.

Consider Adding a Mini-Split to Supplement Your HVAC System.

Sometimes the situation just becomes too much for our single-zone central HVAC system to handle. Renovations that add rooms to your home or that turn formerly separate rooms into a large open area can create havoc for your existing comfort system. 

Perhaps all your trusty central HVAC system needs is a little bit of help. Nick’s Air Conditioning proudly offers our customers the complete line of Mitsubishi Electric® mini-split heat pump products. 

Mini-splits are self-contained HVAC systems consisting of an outdoor compressor unit connected to an indoor air handler unit installed on an exterior wall. Installing a Mitsubishi Electric mini-split in an area of the home that is underserved by your central HVAC system adds comfort and allows the homeowner to customize their home’s climate. 

Heating your home with a mini-split in the winter, either with a multi-zone system for the entire house, or a single-zone unit for one room, gets easier and more efficient with mini-split heat pumps. With a Mitsubishi Electric multi-zone heat pump system, you can heat or cool individual rooms, leaving any unoccupied rooms untreated. 

Let Nick’s Balance Your Air Temperatures Without Breaking Your Budget! 

Nick’s Air Conditioning can help you assess your home’s current comfort condition, check your walls, ceilings and roofs for air leaks or areas that just need more insulation. Let one of our experts ensure that your HVAC system is sized properly for your home, and that all of its functions and features are working as they should. 

It might be time to consider installing a new HVAC system if yours is over ten years old and just isn’t performing to the level it used to. Nick’s Air Conditioning exclusively offers Trane® Technologies products –which includes Mitsubishi Electric Mini Splits—due to their incredible performance, efficiency, and length of life. 

Give Nick’s a call to discuss any HVAC issue you may be experiencing, and one of our trained professionals will be on their way to get it solved fast. 

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