How to Get More AC Fan Pressure on the Second Floor

Tips for Air Conditioner Fan and Air Flow Improvements

You rely on your air conditioner to keep your home cool during the hot summer months. Without it, your entire house would be almost unlivable – hot, humid, and stuffy in ways that are at best uncomfortable, and at worst dangerous.

But for properties that have two or more floors and central AC, it’s not uncommon to find that, on hot days, the second floor is far warmer and more uncomfortable than the bottom floor. Since the second floor is typically where the bedrooms are, this can make it almost impossible to spend any time upstairs during the day, and difficult to sleep at night.

So what is happening? Why is the top floor hotter than the upper floor, and how can we get more cool air up to the top floor so that you and your family can get some much needed cool air?

Why is It So Hot Upstairs?

There are many reasons that the upstairs of your home is warmer on average than the downstairs. Some of these are a result of your air conditioning system while others are more simply a side effect of the physics of hot and cold air.

In general, what is happening in the summer in homes with more than one story is that the downstairs is easier to cool than the upper floors. Since the thermostat is often located on the lower floor, it registers the target temperature far earlier than the upstairs cycles off your AC. This is the result of a range of different factors that include:

• Cold Air Falls, Hot Air Rises – In terms of physics, colder is denser because the molecules are situated more closely together. This makes it heavier and, like any heavier object, forces it to sink. This leads to the cold air collecting on the lower floors of your home while the lighter warm air rises upstairs to become trapped against your attic and roof.
• Your Air Filter is Clogged — The air filter removes particulates from the air it circulates. But if the filter traps too much dirt, the AC blower fan may not be able to continue pushing the air through it. For optimal performance, you should change your air filter at least once a month during the summer, or potentially more if you are struggling with warmer temperatures upstairs or your filter tends to collect more dust.
• Your AC Coils Are Dirty — An AC depends on a system of evaporator and condenser coils that have refrigerant running through them. The evaporator coils in the air handler extract the heat from the air and the fans return this now cooled air back inside. Meanwhile, the refrigerant circulates through the condenser coils on the exterior of the air handler to disperse that warm air back into the outdoor environment. If the coils have become dirty, there is less space for heat transfer to occur, which can make it more difficult for your AC to discharge warm air. This could result in that warm air blowing back into your home.
• Air Flow Pressure Will Look for the Easiest Exit – If you put your hand by any of the registers and air vents, you’ll feel barely any force, as though only a little bit of cool air is making it to the top floor. That’s because your AC system is a network of ductwork, and the path to your upstairs vents is rarely the most direct one. With many air handlers located outside at ground level, upstairs rooms are often the furthest away and much of the cool air will have dispersed through ductwork that offers a closer and more direct path to your air handler, leaving less air for upstairs rooms.
• Your AC Isn’t Functioning Properly – Air conditioners, like any appliance, get old. You will need ongoing AC tune ups and AC repairs if you want your air conditioner to continue to function properly.
• Your Attic Has Poor Insulation – If your attic does not have adequate insulation, any cool air that is delivered to your upstairs floors could be escaping into your attic and out of your house without giving you any cooling benefits.
• Upper Floors Are More Exposed — In many homes, lower floors are partially shaded by trees and nearby buildings that can help keep the walls and windows from getting direct sunlight. Conversely, your upstairs roof and walls often receive direct sunlight throughout the day, keeping the upper floors consistently warmer.

These challenges mean that the upper floors of a home are going to naturally be warmer than the ground floors and the average air conditioner will be at a disadvantage in providing uniform cooling to both upper and lower levels. Fortunately, there are many different ways that you can increase the cooling capabilities of your air conditioner for your second floor and help keep upper floors cooler overall.

One of the main ways to handle these challenges is to increase the AC fan pressure so that your upper level vents are outputting more cool air into your space. We will go over the right ways to do this, as well as the strategies you should and avoid some additional tips that you can use to boost your AC cooling power and keep upstairs rooms more comfortable during the summer.

What Not to Do to Increase Fan Pressure for Your AC

The internet or advice from family and friends can provide you with many different solutions for increasing cool air in your upstairs spaces, but not all of these are the best practice to use in your home. Many solutions fail to take into account the delicate nature of an air conditioner and ductwork, leaving these solutions often ineffective or giving them the potential to cause extensive damage to your central air conditioner.

Here’s what you should NOT do:

• Close The Bottom Floor Registers – There’s a tendency to want to close all the air vents on the bottom floor so that cold air is forced up to the top floor. Although his works in theory, in practice, it is not good for your air conditioner. Your AC is a very delicate system. It is designed for a specific amount of airflow. When you close the bottom floor registers, you may feel a bit more air upstairs, but you also risk your AC coils freezing, and run the risk of long term damage.
• Remove the Air Filter – Air filters do have a tendency to slightly reduce the power of your AC. But removing the air filter could cause damage to your air conditioner by clogging it with dust, which will ultimately cost you more in the long run and cause more problems for your system. In the meantime, you will also deal with more dust and allergens in your home.
• Install a Larger Capacity AC — The conclusion that you need a higher capacity AC to cool your upstairs, as well as your downstairs, can actually be extremely costly without helping the situation. A larger AC unit that exceeds the capacity needed for your home will exponentially increase your electricity costs. The overcooling will also cause parts to ice over and excess humidity, both of which will cause your home to feel even warmer than it did with a smaller AC, as well as cause damage to different components that will be costly to repair. There ARE situations where you need AC replacement – including for a higher powered AC – but that is not necessarily due to the poor upstairs cooling. 

Generally, you should proceed with caution before taking any steps to increase the functionality of your AC system. For the vast majority of homeowners, these are not DIY projects. To avoid future repairs, you will want to stick with methods recommended by a certified HVAC technician or work with an HVAC company to make any repairs or installations that will help improve your fan pressure.

How to Improve the Fan Pressure of Your AC

When you want your AC to keep your upstairs at a cooler, more comfortable temperature, taking steps to increase the amount of air coming through your vents can often have the most significant effect. There are a number of ways to achieve this depending on the specific limitations you are currently facing, your budget, and how much additional cooling you want in your home. Effective solutions include:

• Have an HVAC Contractor Rewire It – On some AC models, it is possible to adjust the blower motor speed in order to increase the CFM, or cubic feet per minute, of air that a fan can push through. An HVAC contractor can rewire the motor to adjust the blower speed on compatible air conditioners to increase the amount and pressure of the air coming through your vents.
• Switch to a Less Efficient Air Filter – The minimum efficiency reporting value (MERV) describes how efficiently a filter traps dust. The truth is that most homes do not need ultra thick air filters with a high MERV rating to pull the smallest particulates out of the air. Homes simply do not have this level of bacteria that they need to prevent. As a result, an overly efficient air filter will clog up easily with all of the standard dust that is in homes, blocking airflow and causing the entire system functions less efficiently. Switching to an air filter with a lower MERV rating will still be enough to filter out dust while still allowing air to flow through more easily.
• Replace or Repair the Fan – An AC has two fans. The first is inside and is responsible for blowing the cooled air into your home. The other is in the air handler and blows the air over the condenser coils. If either of these fans is not spinning or not moving with enough force, you’re not going to get cool air all the way into the upstairs of your home. There are a number of reasons a fan may not work, including a broken belt, blower motor, or a bad electrical connection. AC repair can restore the functionality of a fan or replace an AC fan that has stopped working.
• Fix Leaky Ducts – In the average home, ductwork for central air conditioning leaks approximately 20% to 30% of the air that moves through it out into the attic or wall space. This severely reduces the pressure and amount of air that then blows into upstairs bedrooms and living spaces. Other issues with ductwork, such as when ductwork is bent or collapsed, can reduce airflow even further. Duct sealing can help reduce leaks, and an HVAC technician can inspect your ducts for other problems.
• Adjust Dampers in Ductwork — There is a damper at every junction of your ductwork that can help control the flow of air. This is an alternative to shutting off downstairs registers. By adjusting the dampers, you can reduce the amount of air going to downstairs spaces and redirect it to the second floor.

Which of these methods will have the best result depends on a variety of different factors. Many homeowners benefit from using multiple solutions in conjunction to provide better cooling for their homes, particularly if the difference between upstairs and downstairs temperatures is significant.

Other Solutions for Keeping Your Upstairs Cooler in the Summertime

Increasing fan pressure can significantly help balance temperatures, but there are also additional steps you can take to provide better cooling for your upstairs space. These options can provide everything from smaller scale solutions to total overhauls of your AC system when your current fan pressure simply does not provide enough cooling. You can try options such as:

• Check the Registers — This may seem obvious, but is often overlooked by homeowners, especially in older homes and for new homeowners, but is often a cause of a warmer upstairs since closed or broken registers are an easy way to keep air from getting through. You should check all of your upstairs registers to be sure that they are fully open. You can hold the register up to the light and as long as light shines through, they are good.
• Install Duct Booster Fans — Even with a well working AC fan, it may not be possible to get enough air pressure all the way into the upstairs of your home if the distance is too far. Duct booster fans can continue to move air forward. You can install either an inline duct booster fan that goes directly into your ducts or a register booster fan that you install in place of your current registers. Register booster fans are usually better for less complex and smaller systems, or a single inline duct booster fan will work for many homes. A drawback to these is that they can create a loud white noise when they run.
• Install an Attic Fan — Since warm air rises, hot air will rise into your attic and can become trapped there. Having all this hot air just above your upstairs rooms can make them difficult to cool. An attic fan and proper attic ventilation can help move the warm air out of your home entirely, creating more space for cool air.
• Enlarge the Upstairs Return Vent — An AC works by taking the hot air in your home, extracting the heat from it, and then returning it back into your space. The AC pulls air out via the return vents and ducts. If your upstairs returns are smaller, your AC may not be able to pull out enough heat to make the room feel adequately cool. It may be possible to enlarge the upstairs vents and return ducts so your AC can circulate air more easily.
• Install a Dual Zone System — Dual zone systems come in two different types. The more affordable, but potentially less effective, one uses a series of dampers and controls, along with a thermostat downstairs and upstairs, to let you adjust temperatures by zone. The more effective option, but also the most expensive in this guide, is to install an AC upstairs as well as downstairs. This enables you to set both separately to deliver the most targeted cooling for your upstairs.
• Replace Your AC – An AC naturally becomes less efficient and powerful as it ages. An AC that is 15 or 20 years old will not have the same capabilities to get cool air to the top floors of your home as a newer AC will. If your AC is older, you are struggling with fan pressure in certain rooms, or you are experiencing more frequent repairs and problems, replacing an AC may be a cost effective solution to fix the problem.
• Look Into Smart Thermostats — Some smart thermostats today can help you tailor your cooling more accurately for your home. This can help alleviate temperature differences between upstairs and downstairs spaces. Upgrading your thermostat may help you use your existing air conditioner more effectively and efficiently.
• Install a Ductless Mini Split System – A ductless mini split system AC is a heat pump that uses an outdoor air handler and an indoor unit. Each indoor mini split can effectively cool one room or smaller space, although you can connect several mini splits to one air handler. They do not use any ductwork making them affordable to install, and they operate quietly. A ductless mini split AC can provide additional cooling upstairs alongside your central air system and lets you set the temperature of each room independently.

These solutions range from quick and affordable to more involved. All are best used in conjunction with methods like keeping windows and shades closed during the day to prevent solar heat from getting into your home.

Another important step is to schedule annual AC maintenance, ideally in the spring. During the service, an HVAC technician will perform an inspection and a tune up. This is a good opportunity to identify any problems that may prevent your AC from adequately delivering cool air to the upper floors of your home in the upcoming summer. It also involves checking and fixing electrical connections, fan belts, air filters, condenser coils, and other components that can wear out or begin to fail with time.

This helps your AC work more efficiently and sets your home up to receive more ven cooling so that you can keep your upstairs and downstairs comfortable without having to face an increase in your electricity bills.

AC Repair and Fan Pressure Solutions in Nashville from Lewis Comfort Control

Identifying the reason why your fan pressure is low in your upstairs is not always straightforward, and once you determine the reason, you may also have to implement a fix or new installation to get the results that you want from your AC. A local HVAC company can help with this.

For homeowners in Nashville, Lewis Comfort Control provides HVAC repair, replacement, tune ups, and other central air services to local homeowners. We can determine what issues may already exist that are preventing you from getting adequate airflow upstairs, and provide personalized recommendations to help you improve the comfort of your home. To learn more about how we can increase the cooling capabilities of your AC or provide a new AC that will offer improved functionality, contact our team at Lewis Comfort Control.