What Is Static Pressure In Your HVAC System?
You may already know what static pressure is, even if you’ve never heard the term before. It may be the reason your home isn’t as warm in the winter or as cool in the summer as you’d like it to be. Or why the air feels “stale” in some rooms.
We’ll get into more detail below, but here’s the basic idea: Static pressure, in the HVAC world, is the measure of how much resistance air faces when it’s trying to travel through the ductwork. The more resistance it meets, the weaker the airflow.
That’s the quick explanation. If you’ve noticed any of the problems we mentioned, we’ll get more in-depth by going over:
- Explaining Static Pressure
- Signs Of A Problem At Home
- Four Causes Of Static Pressure
- How To Reduce Static Pressure
If you’ve noticed any of these problems in your South Central Pennsylvania home, give us a call or click below for a free consultation! We’ll walk you through the process of testing for this problem. And, we’ll recommend the best way for you to handle it.
Explaining Static Pressure
Let’s get more specific: static pressure measures everything that causes resistance to the air flowing through your HVAC system. That’s the filter, turns in the ductwork, and anything else you’ve installed, such as a dehumidifier or air purifier.
Anything that blocks the free flow of air creates static pressure. It’s inevitable, but there’s an acceptable level for it.
We measure the pressure by inches per water column. You might see it referred to as “inches H2O” or “wci.” It’s a close cousin to pressure per square inch or PSI.
Anyway, .9 wci and below means you have normal pressure. Anything higher could mean there’s a problem.
Signs Of A Problem At Home
The three main problems you’ll get with static pressure are:
- Upstairs Too Hot Or Too Cold
- Air In The Bedroom Feels “Stale”
- Weak Air Circulation Or No Airflow
Upstairs Too Hot Or Too Cold
The most common complaint we hear when it comes to this problem is that an upstairs room — usually a bedroom — is too hot in the summer and too cold in the winter.
There are a few reasons why this may happen. But, static pressure is a common culprit.
With all that resistance, there’s not enough heated or cooled air coming through the vents. The system loses pressure along the way with every turn, vent, or leak before the air gets to that room. The further the vent is from the furnace, the worse the problem becomes.
Air In The Bedroom Feels “Stale”
Remember: your HVAC system doesn’t just pump air out through the vents. It also draws air from each room through a return vent. And, when there’s too much static pressure, the air in your room stays where it is.
The result is “stale” air. It’s stagnant and doesn’t feel fresh. Since the system relies on circulating air through the house, you’ll notice when it’s not working right.
Weak Air Circulation Or No Airflow
We hinted at this already, but weak air circulation — or no airflow at all — is a sign that something’s wrong. Not only does it make a room or part of the house uncomfortable. It can also damage your HVAC system.
A furnace, in particular, isn’t made to store heat. But, when there’s a backup in your system, that warm hair doesn’t escape the unit as it should. When it stays put, it can overheat and damage the equipment. This can lead to a breakdown.
Because of this, you should call an HVAC contractor to look over your system — and your ductwork — if you notice these problems.
Four Causes Of Static Pressure
Four common causes of static pressure are:
- Wrong Air Filter
- Clogged Filter
- Ductwork Leaks
- Poor Ductwork Design
We listed these starting with the easiest and least expensive to fix and working our way up from there.
Wrong Air Filter
Your air filter will produce a small amount of resistance as it traps dirt and dust. That’s why you need to pay attention to the MERV rating. Anything over a 12 may be too strong for a residential system. And, if your furnace isn’t the strongest, you may need one with a lower rating.
We go more into detail about air filters in this article.
A related problem is a filter with the proper rating, but you’ve had it installed for too long. You should replace your air filters at least every three months. If it’s been in there for longer, it may be so gummed up that air can’t pass through anymore. If you pull out the filter and it’s grey, it’s clogged.
Next are holes or splits in your ductwork. Air escapes through every one of these, which means there’s weaker circulation further down the line.
Poor Ductwork Design
Unfortunately, poor ductwork design is the most common cause of static pressure. That’s especially so if you’ve always noticed this problem.
Take a look at your furnace. Odds are, the ductwork attaches to the top of it, causing the air to go in a 90-degree turn. For decades, it’s been the easiest way to design and install ductwork. But, it causes a lot of resistance. Ideally, that turn should be no more than 45 degrees. But, that usually requires a custom build, and most contractors didn’t account for that when they built the house.
How To Reduce Static Pressure
Here are your three steps toward reducing static pressure in your HVAC system:
- Change The Air Filter
- Ductwork Sealing
- Redesign Ductwork
Change The Air Filter
The first step is a simple one: Change the air filter. And make sure the new one is okay for residential use. Go with MERV 10 or below. If nothing changes, it’s time to call a professional.
If you or a tech can spot holes in the ductwork, sealing it may be an option. The problem here is that you can only address what you can see. There may be more holes or problems behind a wall.
The most expensive option — but often the most effective — is to redesign the ductwork. This usually means getting rid of the 90-degree turn coming out of the furnace. You’d need a custom piece made for your furnace that allows the air to flow at 45 degrees instead.
As you can see, there are a lot of options to choose from. Depending on your exact situation, you may get away with an easy fix. Or, we’d need to work with you on a more comprehensive solution. Either way, Air Comfort is here to help! If you live in Camp Hill, Manchester, York, or anywhere in South Central PA, click below or call us today.