One of the most common questions we receive from homeowners is, “What is CFM in HVAC?” CFM stands for Cubic Feet per Minute, a measurement of the amount of air moving through your HVAC system. Whether you’re purchasing a new HVAC unit or upgrading an old one, understanding CFM requirements helps you choose the right system for your home. In this blog, we’ll explain how airflow volume affects energy consumption, system performance, and indoor air quality, as well as how to determine the proper CFM for your house or business.
Why HVAC CFM Is Important
CFM is directly related to the air exchange rate or air changes per hour (ACH), the amount of times the air inside your home is replaced by fresh air from outside. Proper airflow has numerous benefits for your health and ventilation system, including:
- Improved Air Quality. Strong circulation prevents pollutants such as dust, dander, and allergens from triggering respiratory ailments. Cycling air also lowers radon and carbon dioxide levels.
- Reduced Moisture. Homes with little airflow have higher humidity levels, which makes them more likely to develop mold, which can lead to respiratory issues and infections, as well as widespread structural damage.
- Improved Comfort. Consistent air movement allows your furnace, heat pump, and air conditioning to warm and cool your home effectively.
Choosing the correct airflow rate also prevents your HVAC system from overworking to compensate for hot and cold spots throughout your home. An overpowered or underpowered blower leaves some parts of your house feeling drafty while others remain stuffy.
How to Calculate CFM
CFM calculations are based on a room’s area, ceiling height, and desired ACH. For a standard home, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends one complete air change per hour. An ACH of 0.35 is their absolute minimum. The basic formula for calculating CFM is:
CFM = Room Volume (Cubic Feet)/Minutes per Air Change
Keep in mind that the need for ventilation increases as the number of occupants goes up. A detached, family home only requires one ACH, while an office or retail shop requires 2-3. Someplace crowded, like a restaurant, might need as many as 6-8. A common rule of thumb is that you need one ton of power for every 400 CFM. So if your home requires 1,200 CFM, you’ll need to install a 3-ton furnace, heat pump, or air conditioner.
HVAC systems are also measured in BTUs. A one ton furnace, heat pump, or ac unit generates approximately 12,000 BTU, so in order to maintain air circulation in a home with a required CFM of 1,200, you’d need a system capacity of 36,000 BTU. Information about CFM is normally listed on the specification sheet, which is located on the unit itself or in the owner’s manual. Though the ideal CFM depends on the size of your home, the average house requires 1,000 – 2,000 in order to maintain sufficient airflow.
Save on HVAC Repairs with Agway
Strong airflow not only requires the right CFM, but expert technical support as well. Every HVAC system experiences some degree of wear and tear over the course of its lifetime. Home insurance doesn’t cover this type of damage, but we do. Agway’s EnergyGuard™ Repair Program protects your heating, cooling, and electrical systems from problems caused by daily use.
When the need for repair occurs, our customers don’t have to waste time searching for a qualified technician. They contact us instead. We maintain a network of qualified HVAC professionals in your area. As soon as you report the problem, our team sends the first available one straight to your door. There are no service fees or deductibles either. We pay for the visit and all covered parts. Don’t let a sudden breakdown upset your finances. Sign up and start enjoying the benefits of EnergyGuard™ today!
