An air pressure gauge

What Is Static Pressure?

If at any point you’ve ever bought an HVAC system or have had an HVAC system serviced, you probably have heard someone talk about Static Pressure. Hopefully, they explained what it was and didn’t just rattle off jargon. If they did not, or if this is your first-time hearing about static pressure, then you might have some questions. Obviously, it’s important, otherwise we wouldn’t have an entire article dedicated to it. So, what is static pressure?

Static Pressure is the amount of resistance to airflow in an HVAC system. Specifically, this measures the resistance to airflow coming out of the ductwork.

In this article, we’ll explain why static pressure is important and how you can make sure your HVAC system has the right amount.

Why is Static Pressure Important?

Diagram of An Air Scoops Air Flow

We can think of static pressure similarly to how we think about water pressure in a shower. Too much or too little can lead to problems. Most HVAC contractors consider 0.5 inches to be the ideal static pressure.

With too little water pressure, you’re only going to get a slow dribble of water out. That’s no good for actually using your shower. With too much, the water is going to come rushing out of the pipes, possibly damaging them. It’ll be too uncomfortable to use and might actually take the shower head off.

Similarly, with too much or too little static pressure, you may not even notice that air is coming out of your vents. This can lead to long run cycles and high energy bills while your home is still uncomfortable. This issue can also damage or break equipment in your HVAC system. Repairs and replacements can be costly if you’re not protected by a warranty.

What Problems Come from Having the Wrong Static Pressure?

As we said earlier, too much pressure can damage equipment. Here are some specifics of what can come happen if there is too much pressure:

- Noisy HVAC Equipment
- Part Failure
- Dangerous Equipment Failure
- Duct Leaks
- Long Run Cycles and High Energy Bills
- Uneven Heating and Cooling
- Uncomfortable Humidity
- Poor Air Filtration

What Makes Equipment Failure Dangerous?

As you may have noticed, we have listed part failure and dangerous equipment failure as two separate issues. This is because you might experience a part failure that only needs a quick repair and leaves you without heat for a day, or a much more severe breakage that requires a large replacement and poses a health risk to everyone in your home.

The strain incorrect static pressure places on a system can burn out the blower fan. Which will disable your HVAC system until it’s replaced, but your home will still be livable.

If the furnace is burning fuel to create heat and that heat is not being blown out of the heat exchanger, this can cause overheat and crack the heat exchanger. This is a much more severe problem as the gases being used for fuel can escape into your home.

Indoor Air Quality and Comfortability

Not having enough pressure can cause an uncomfortable interior for your home. Your HVAC system will not blow hot or cold air into your home quick enough for it to be even. This means you will have lots of spots that are too hot or cold.

The HVAC system also cannot provide additional benefits like humidifying or dehumidifying your home because it cannot keep up with the ambient humidity. It will also not be blowing air through the filter at a regular rate. That means that dust, dirt, allergens, and other pollutants can collect in the air in your home.

What Causes Static Pressure to be Too Low or Too High?

There are three common problems that will affect the static pressure in your home.

Dirty Air Filter

This is the easiest problem to manage and remedy. Having a dirty air filter will restrict air flow and can trap air inside your HVAC system. Check and replace your air filter regularly.

Poor or Mismatched Ductwork

An assortment of hard duct work

The most common cause of improper static pressure is having ductwork that is the wrong size for the home or the equipment. Ductwork actually comes in a handful of different shapes and sizes. Having ductwork that is not the right size or does not taper correctly at the air supply side or the furnace return can lead to that whole slew of problems will listed above.

Incorrectly Sized Equipment

This is the most common cause of static pressure related problems. Having a furnace that is the wrong size for your home is also going to have a drastic impact on the air flow. A furnace that is too small isn’t going to produce enough airflow. A furnace that is too big is going to create far too much airflow.

According to a study from the Department of Energy, roughly half of the residential homes and buildings they surveyed had HVAC equipment that was the wrong size.

How Are Static Pressure Problems Fixed?

So now that we know what causes the static pressure in our ducts to be wrong, what can we do to fix those problems?

Minor Adjustments to the Ductwork

The good news is that the fix is sometimes relatively minor. An HVAC professional can change the static pressure of an HVAC system by changing the sizing of one piece of ducting or adding to the return. By narrowing or widening the passage that air flows through, the technician can increase or decrease pressure accordingly.

As long as the rest of the system is the right size and working as intended, this fix can be quick and inexpensive compared to getting a different size furnace.

Getting the Right Sized Equipment

This fix is the costliest. If your furnace is the wrong size for your home, consult with a HVAC professional about getting a furnace that is the right size. This will also ease a lot of other issues that come with an incorrectly sized furnace. Of course, this means paying the price for a new system, but depending on energy usage and prolonging equipment lifetime, it’s possible to save more money during the furnace’s lifetime.

Equipment Repair and Replacement

Sometimes it can just be a matter of replacing a faulty blower fan, or a similar fix. When your HVAC technician inspects your system, they will determine if the problem is in the ducts, furnace size, or if a part is failing.

How To Prevent Static Pressure Problems?

Fixing problems is great, but preventing them is even better. Here we’ll talk about ways to prevent static pressure problems.

Choose the Right Contractor

A technician performing a furnace tune up

This is one solution that will save you a lot of headaches in the long run. You will get the optimal performance and life span out of your HVAC equipment by having a Performance-Based Contractor install it.

You want a contractor that will take your entire home and all the required equipment into account. A good contractor will perform calculations to ensure that you are getting the right size of equipment and that your system will have the right static pressure to prevent future problems.

Make sure that your HVAC professional doesn’t just give you any old furnace, turn it on, and call it a day.

Have Your System Regularly Serviced

It’s recommended that you have an HVAC professional look at your equipment at least twice a year. Once in fall, to inspect the heating elements, and once in spring to inspect the cooling elements. During this inspection, they should be able to detect any issues with the static pressure.

Replace Your Air Filter

This is a simple solution that you can do yourself. Replace your air filter often and with good quality air filters. Replace your air filter with the manufacturer recommended time frame and make sure that it is not dirty or developing a buildup that could restrict air flow.

Inspect Your Central Ductwork

While you are replacing your air filter, inspect the ducting connected to your furnace. If you have ductwork in the attic, give it a visual inspection frequently as well. Make sure that no cracks or leaks have developed.

Keep Vents Unobstructed

Make sure that the vents and registers in your home are clear of obstruction. Keep furniture and large objects away from them to ensure they can blow air. Large objects can also collect dust and particles that can travel into your vents and build up in your ducts or on your air filter.

Monitor Air Quality

Take an occasional look at your vents and registers. Make sure that they are blowing air when they are supposed to and that they are not blowing out dirt and dust. If they are blowing out debris, it could be a sign that something is wrong in your ductwork, and you should contact your local HVAC professionals.

Who Are Advantage Heating and Air Conditioning?

We are your local HVAC Experts out of Salem, Oregon. We hope that this post gave you the information you need to answer all the questions you had about static pressure. If you have other questions about HVAC systems, check out our other [blogs](https://www.advantageheatingllc.com/learning-center/). To learn more about who we are and how we can help you, visit our website and follow us on social media - we’re here when you need us!