Nominal Vs. Actual Air Filter Size

Air quality is rapidly decreasing in this world and this major issue is affecting every living being on Earth. Exposure to poor air can cause harm to health and make the environment unhealthy. The quality of indoor air is poorer than the outdoor air and to fix that the first residential air filter was introduced in 1963 in Germany. In all of this time, filters are developed now and they come in many variations and sizes. Filters are used with the HVAC (heating, ventilation, and air conditioning) system and every system has different air filter size specifications.

An air filter has two different types of sizes which are nominal size and actual size and understanding both is important for the HVAC system and its user. Without learning about the filter’s sizes people can make mistakes and face many problems like less efficient filtration, high energy bills, poor indoor air quality, and many more. In this blog, individuals will learn in detail about nominal and actual size and this helps them to decide which filter size suits best for their HVAC system.

What Is Nominal Size?

The nominal size of an air filter means standardized dimensions of the filter in whole numbers that manufacturers use to label their filters. The meaning of nominal is “in name” which means that the nominal size is used to give names to the filters rather than providing its exact measurement. If an exact measurement of an air filter is 14.5” x 29.5” x 1” then its nominal size will be 15” x 30” x 1”. The nominal size helps individuals find compatible air filters for their HVAC system without measuring their existing filters. 

What Is Actual Size?

The exact dimension of an air filter is known as the actual size. The actual size of an air filter is measured to show its fractional or decimal part. If an air filter’s labeled size is 30” x 36” x 1” then its actual size would be 29.5” x 35.5” x1”. The actual size is most of the time a little smaller than the nominal size. This site helps people find air filters that fit their HVAC system perfectly without any problem. So it is important to know about the actual size of an air filter.

Importance Of Understanding Air Filter’s Size

Understanding an air filter is very important because it will make sure that the filter fits into the HVAC system properly and works properly. Here are some of the key points for understanding an air filter’s size:

1. Efficiency

The efficiency of an HVAC system and an air filter is important and proper knowledge of filters will help individuals to guide them to buy a perfect-fitting filter. Air filters that fit properly inside an HVAC unit will make sure that the unit is working efficiently. The system will get clean air which helps it to control the temperature of the indoor environment properly.

2. Proper Filtration

Air filters clean indoor air and to make sure that they are doing their job efficiently people should know about the nominal and actual size of the filter. When a filter fits inside the HVAC system perfectly it has optimal filtration efficiency. So it is important to know about the actual and nominal size of existing or previous air filters.

3. Increase Indoor Air Quality

A properly fitting air filter helps to increase indoor air quality significantly because there will be no space for air to pass without getting filtered. A perfect-sized air filter makes sure that it removes airborne particles from the air sufficiently.

4. Increases HVAC’s Lifespan

People who understand filter sizes know that it is so important for their HVAC system’s life. Air filters that fit properly in the HVAC unit protect the unit from large airborne particles efficiently and due to this the HVAC system works efficiently and increases its overall lifespan.

How To Identify The Right Air Filter Size

Identifying the right air filter size is important so it can work with the HVAC system efficiently but many people don’t know how to identify their filter’s size. Here is step by step guide to find the filter’s size:

Step 1: The first step anyone can do is to check their previous filter’s size. Most of the time air filters are labeled with the nominal size.

Step 2: If the previous filter has no size labeling individuals can measure the actual size of the filter by themselves.

Step 3: Checking the HVAC manual can be helpful because the size of the filter is usually mentioned in it.

Step 4: If an exact sized air filter is not available then buy a filter that has a very small size difference.

Effects Of Wrong Filter Sizes

Wrong size air filters will have some side effects on the HVAC system and indoor environment and many individuals make the mistake of buying a filter that doesn’t fit into their HVAC system. Here are some of the common effects of wrong-sized air filters:

1. Poor Indoor Air Quality

If a filter doesn’t fit properly into the HVAC system it will not remove contaminants from air properly. A filter that is smaller than the required size will let the dirty air pass from it and the HVAC system spreads the dirty air all around the house. So always make sure that the filter is increasing the air quality not decreasing it.

2. May Cause Damage To HVAC System

If an air filter size is smaller than the HVAC system’s supported size then it may cause damage to the HVAC system. A small filter will leave gaps and form so their particles can pass, then they will go to the components of the HVAC system and cause damage to it. A larger filter can make the HVAC unit work more and that will cause overheating as a result damage can occur.

3. Decreases Efficiency

A wrong-sized filter will affect the efficiency of an HVAC system because it can interrupt the proper air supply. A large air filter can restrict airflow and due to this, the system will not get enough air to do its job effectively and the time for changing the temperature of the environment will increase.

4. Increase Energy Bills

One of the main side effects of using a wrong-sized air filter is it can cause an increase in energy bills. If an individual uses a filter that is larger than the recommended size then it will not allow air to pass properly which will reduce the air supply. The HVAC system will force its components to work more and that will consume more energy as a result energy bills will increase.

Avoid Common Size Choosing Mistakes

Many people need to correct some things while checking and finding the right size air filter for their HVAC system and due to this mistake they face many problems that affect their pocket and indoor environment. Here are some of the common mistakes that people make while selecting the proper size air filter:

1. Cross-Check Manufacturer’s Specifications

Most of the time people make the mistake of not double-checking their air filter’s manufacturer’s size specifications. This mistake led them to buy a filter that didn’t fit properly to their HVAC system and due to that, they wasted their hard-earned money as well as decreased the efficiency of their HVAC system. So always cross check manufacturer’s specifications before investing in an air filter.

2. Always Rely On Actual Size

When people go to buy a new air filter most of the time they rely on the nominal size of the filter which is a huge mistake because the actual size of an air filter is always a little smaller than the nominal. So always make sure to rely on actual size whenever buying a filter because it will ensure that the filter fits inside the HVAC system perfectly otherwise the wrong filter can create many problems instead of giving benefits.

3. Buy One Filter Before Bulk Purchases

One of the most common mistakes that people make while purchasing an air filter is that they buy filters in bulk without confirming whether the filter fits perfectly inside the HVAC system or not. So it is wise to buy a single air filter and test it because it will ensure that the filter is fitting inside the HVAC unit properly and buying that filter in bulk will not be a waste of money.

Comparison: Nominal Vs. Actual Air Filter Size

Conclusion

The quality of indoor air is important because it helps to promote a healthy life but due to air pollution maintaining good air quality inside homes can be a problem for many individuals. Many people make a very common mistake while purchasing an air filter which is buying the wrong size air filter. Individuals most of the time don’t understand the difference between the nominal and the actual size of the filter. The nominal size refers to the filter’s size which is in whole numbers and this helps in the filter’s purchasing.

The actual size of a filter refers to the exact measurement of a filter which is written in decimals or fractional formats and this helps to ensure that the filter is fitting inside the HVAC unit perfectly. A perfect-size air filter ensures the efficiency of air filtration and the HVAC system stays at the optimal level. A wrong-size filter can create problems like poor air filtration, poor temperature control, an increase in energy bills, etc. So finding a proper size air filter for an HVAC system can be difficult but Custom Filters Direct is here. We provide customized size filters with high quality to our customers. To learn more about our services contact us at (877) 812-7983.

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