Hvac how many cfm

This is a handy rule of thumb for estimating the cooling load for a densely populated area, like an auditorium, gymnasium or sanctuary. For example, if an auditorium will have up to people at maximum capacity, the cooling load would be close to 40 tons x 0.

If the space is insulated well, this rule of thumb reduces a bit to 0. Just like all rules of thumb, this is just a place to start, and will heavily depend on insulation factors and heat generating equipment. In reality, most commercial buildings offices, retail, schools are probably closer to btuh per square foot, but warehouses or areas with more ventilation could require btuh per square ft or sometimes even more!

This also depends where in the country or world you are. In the midwest this is a good rule of thumb. If you are in southern California, or in the arctic circle, this rule of thumb is not so helpful.

If you need to quickly determine how much cfm you need to deliver to a space, this is a great place to start. Measure and record the supply air temperature at this point.

Disconnect power and reset the blower speed back to its original setting. Determine the Delta-T by subtracting the return air temperature from the supply air temperature. Record this value. Divide the BTU rating of the gas fired furnace by the value determined in step 7.

The answer is your airflow in CFM. Wait for all stages of heat to energize. If this is a heat pump, make sure ONLY the electric heat is operating for this test. Using your voltmeter, measure and record the supply voltage to the air handler. Using your ammeter, measure and record the total amperage drawn by the air handler. Multiply the recorded supply voltage by the amp draw. This gives you the power in Watts. Multiply the answer derived in step 4 by 3.

This converts Watts to the BTU output of the electric heat. Most packaged air conditioning equipment is designed for, and rated at, CFM per ton. Typically, a 7. For example, the unit might be specified to deliver 3, CFM at 0. As we increase the air quantity on a particular unit, three things happen:. For our purposes, latent capacity is the ability of the unit to lower the humidity or to remove moisture from the air and sensible capacity is the ability of a unit to lower the air temperature.