CFM, cubic feet per minute, determines how many cubic feet can be moved or exchanged each minute. This article will go over how to calculate CFM and how often air needs to be exchanged.
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What Does CFM Stand For?
Cubic feet per minute is referred to as CFM. A fan moves a certain amount of air in a minute, expressed in cubic feet, and this measurement describes that amount of air movement.
Usually, CFM refers to exhaust fans, which have a few hundred cubic feet per minute of airflow. Professional-grade fans, like range hoods, can move up to 2000+ CFM of air, and commercial hoods can move up to 5000+ CFM. As a measure of how quickly stale air leaves a space, think of cubic feet per minute (CFM) as an air flow rate. The faster smoke and steam leave your home, the more CFM a fan has.
For highly powerful specialized equipment, CFM ratings may also be present. To thoroughly clean your ducts, for instance, professional duct cleaning businesses employ equipment with a CFM rating of up to 10,000.
How to Calculate CFM
Now that the question “what is CFM?’ we’ll discuss how to calculate it.
Gas Range
Divide your range’s total BTU output by 100 to determine the airflow of your fan. You will receive the bare minimum CFM from this. A minimum 900 CFM range hood is therefore required for a range with 90,000 BTUs.
However, this figure only takes into account the heat that your range generates; you should also take into account your cooking style.
You should take into account at least 1200 CFM with the 90,000 BTU range in this example if you frequently cook, love Asian food, or eat greasy food.
Electric Range
Since they don’t increase the amount of kitchen exhaust and fumes from cooking, electric ranges require less CFM. Instead, a heating element under the burner powers electric ranges.
You can use the following table to choose the CFM for your electric cooktop.
| ELECTRIC RANGE SIZE | CFM |
|---|---|
| 30″, 36″, 42″ | 600+ CFM |
| 48″ | 800+ CFM |
| 54″ | 1000+ CFM |
| 60″ | 1200+ CFM |
This is just the lower end, just like gas ranges. We advise our clients to purchase range hoods with greater airflow. In comparison to underpowered hoods, they typically last longer, give you more flexibility and satisfy customer expectations better.
You’ll always have access to the most powerful setting in an emergency if your hood has a higher CFM rating. In order to prolong the motor’s life, you can also frequently run your hood on the lower settings.
What is a Good CFM for a Range Hood?
For a range hood, 600 or more CFM is a good measurement. The majority of cooks can use this. As long as you avoid intense high-heat cooking or foods with strong smells, a 600 CFM hood usually won’t leave you wanting more.
900 CFM is preferable to 600 CFM for ardent cooks or cooks with larger ranges, and 1200 CFM is even better. Heavy grease and dirt can be vented through your exhaust system using a 1200 CFM fan. Additionally, it works for outdoor grill hoods.
Is a Higher CFM Better?
Your kitchen fan should always have a higher CFM. A high CFM hood is always operable at lower settings. By moving a significant amount of air per minute, it offers excellent ventilation. An extremely powerful fan is necessary to keep grease out of your kitchen exhaust system if you frequently cook or enjoy Asian cuisine.
A higher CFM may be required as well, depending on the size of your room. The amount of air your fan needs to operate increases with the size of the room. Commercial hoods produce thousands of CFM while residential kitchen fans only reach 2000 CFM. These fans, however, are not intended for your house.
Remember that not all manufacturers offer hoods with 2000 CFM. The majority of hoods have a CFM of 600 or less. Because the lower speeds lack power, these hoods are not as adaptable. You can always run it at slower speeds if you have a powerful hood. In your kitchen, it will last a lot longer if you do this.
The amount of air your hood should move should increase with the size of the kitchen range. However, you must make sure you have enough room on your wall or underneath the cabinets. Coverage is even more crucial when a wider area is involved. A hood that is six inches bigger than the cooktop is what we advise getting. A kitchen fan should have a clearance of at least six inches, if possible.
How Frequently Do I Need to Exchange Air?
Determine how quickly the air in your space needs to be exchanged now that you are aware of the volume of air present. Specific airflow requirements depend on your particular setup, but here are a few general examples of recommended exchange rates:
Engine Room, Generator Room, Boiler Room
– Every 1-4 minutes
All air should cycle every 1-4 minutes because the exhaust fumes in these rooms need to be quickly removed. A system that can move 500–2000 CFM would be ideal for an engine room with a 2000 cubic foot volume.
Kitchen, Cafeteria, Bakery, Bar, Laboratory
– Every 2-5 minutes
The typical requirement for moderate-to-high air circulation (roughly every 2–5 minutes) in laboratories and areas where food is prepared or served is that it be present. You should try to find a system that can handle between 400 and 1000 CFM for a 2,000 ft3 area or laboratory that deals with food.
Warehouse, Industrial, Machine Shop, Factory
– Every 3-7 minutes
The majority of industrial spaces still need consistent airflow to get rid of work-related fumes and to keep the air clean, even though it’s not quite as intense as in engine rooms or food spaces. An industrial space of, say, 2,000 square feet would typically need a system that can push 280–670 CFM.
Classroom, Home, Office, Store, Gymnasium, Restroom, Auditorium
– Every 4-10 minutes
In comparison to the other types of rooms mentioned above, homes and public spaces like offices, retail stores, and conference rooms require a little less maintenance. A system with a capacity of moving 200–500 CFM is needed to move the air in a 2,000 ft3 space in these rooms, where air exchange is typically not as important.
What is CFH?
Although the equipment is occasionally measured in cubic feet per hour, or CFH, range hoods are typically measured in CFM (cubic feet per minute). As there are 60 minutes in an hour, this number will be significantly larger than a CFM reading—60 times larger, to be precise.
Equipment that is measured in cubic feet per hour includes gas lines. Due to the fact that gas rather than air is being moved, this rating is typically quite low, particularly in residential applications. To ensure everyone in the neighborhood is safe, gas lines must abide by strict code requirements and safety regulations. The typical residential gas line has a flow rate of a few hundred cubic feet per hour (CFH).
Despite appearing low, one cubic foot of gas per hour produces about 1,024 BTUs, which is enough to power your home’s gas appliances. Therefore, multiply the CFH by 1,024 to get the BTU capacity of your gas line. If they can, your gas appliances may use as many BTUs as this overall. This is the maximum BTU capacity of your gas line.
You could connect gas appliances that produce 204,800 BTUs, or 200*1,024 CFH if your gas line has a capacity of 200 CFH.
Please take note that this is only a rough estimate. You might be able to connect more gas appliances if your natural gas line has sufficient pressure. Before installing more gas appliances, find out the CFH and BTU capacity of your gas line by speaking with a licensed professional or contractor.
Welcome to our CFM article; we appreciate your visit. Check out the articles below for more information on CFM.
