HVAC Air Flow & Odor Control

Proper HVAC air flow is essential for maintaining temperature and humidity control. But did you know that poor air flow can contribute to odor problems?

Lingering odors in a home can be frustrating and even embarrassing. And for your commercial customers, bad smells can drive away customers and impact their bottom line.

Here’s what you need to know about HVAC air flow and how it can help with odor control.  

How HVAC air flow can help eliminate chronic odors 

When there’s an odor problem, of course the first thing to do is identify the source. Unpleasant odors can come from all kinds of sources. In fact, the HVAC system itself can cause odors. For example, musty odors can result when moisture gets into ducts, when drain pans get clogged, or when an air conditioning system fails to control humidity.

However, many times chronic odor problems come from things that can’t be completely eliminated, like smoke in a restaurant kitchen, chemical smells in a hair salon, or odors from a restroom.  

It might not be a problem if the restaurant kitchen smells like smoke, but when the odor migrates to the dining room it’s a different story. And nobody wants their office or retail store smelling like a restroom. That can happen when the HVAC system is pushing air in the wrong direction.

In that case, the best strategy is creating HVAC air flow conditions that move odors outside the space before they can migrate to areas where they bother people. 

To understand how HVAC air flow affects how odors move throughout a space, we first need to understand how air pressure works.

HVAC air flow and air pressure conditions 

HVAC systems have a big impact on air pressure within the space. That’s because heating and air conditioning systems push air into the space, while exhaust and ventilation systems pull air out. The balance between the two is critically important when it comes to odor control.

When more air is mechanically removed from a space than air supplied, the result is negative air pressure in the space. And when the opposite is true (more air is supplied than removed), the result is positive air pressure in the space.

Here’s the critical thing to know: air moves away from an area with positive air pressure and toward an area with negative air pressure. 

Once you understand this critical fact, it’s easy to see how HVAC air flow conditions can contribute to odor problems and how it can be used to correct them. 

In a restaurant, for example, odors from the kitchen may be pulled into the dining area because of negative air pressure in the dining area and positive air pressure in the kitchen. That can happen when there’s poor ventilation in the kitchen, and poor air supply in the dining area.

The HVAC air flow within a space can be impacted by both poor design and poor maintenance. So let’s take a look at some best practices for improving balanced air flow, with the goal of controlling migrating odors along with comfort conditions.

Strategies for improving HVAC air flow

HVAC maintenance tasks to optimize air flow

The first step is to make sure that the system is working as designed. If maintenance has been neglected, supplied air may be reduced. That can impact the movement of odors, create stuffy conditions, and also impact the temperature. Check for the following problems:

• Clogged filters
• Blower motor or fan problems
• Leaking ducts
• Blocked registers or vents

Using HVAC design to control air flow

Inadequate or improperly designed ventilation can contribute to the spread of odors. This tends to be a common problem in buildings that were constructed to be airtight to reduce energy costs. When windows don’t open, the HVAC system bears the burden of creating balanced air pressure and air flow in the space.

Sometimes small HVAC design changes can make a big difference in controlling odors and moving them out of the building. In fact, you can deliberately move air (and odors) in the desired direction by creating negative air flow. 

Consider the following:

• Adding makeup air units to increase supplied air.
• Adding or moving duct runs to change the amount and locations of supplied air in specific areas.
• Adding exhaust fans to increase ventilation in specific areas.

HVAC Techs: boost your knowledge and your career

If you found this article informative and helpful, check out more articles and videos that can help you learn what you need to know to build a successful career in HVAC and Refrigeration service.

HVACR Career Connect NY was created to promote the exceptional quality-of-life benefits of a career in HVAC and Refrigeration service, and also to provide a clear path for getting started in the profession. In doing so, we serve as a resource for employers in the New York City metro area to find and hire smart and capable new technicians. We also serve as an educational resource to support business growth and to help service technicians succeed in their chosen profession.