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Illustration of return air techniques shows supply air returning through grilles in doors and walls, under gaps beneath undercu… | Duct work, Duct, Return air grill
![Duct air flow: HVAC system return air & air flow or air speed measurements in cfm: how to increase air conditioning or heating return air flow Duct air flow: HVAC system return air & air flow or air speed measurements in cfm: how to increase air conditioning or heating return air flow](https://inspectapedia.com/aircond/ducts/ReturnRegister010DF.jpg)
Duct air flow: HVAC system return air & air flow or air speed measurements in cfm: how to increase air conditioning or heating return air flow
![Duct air flow: HVAC system return air & air flow or air speed measurements in cfm: how to increase air conditioning or heating return air flow Duct air flow: HVAC system return air & air flow or air speed measurements in cfm: how to increase air conditioning or heating return air flow](https://inspectapedia.com/aircond/ducts/DuctAtFurnace040DFs.jpg)
Duct air flow: HVAC system return air & air flow or air speed measurements in cfm: how to increase air conditioning or heating return air flow
![Way to balance air flow for HVAC central returns that doesn't require leaving a big gap at the bottom of the door | Whole house fans, Doors, Return air vent Way to balance air flow for HVAC central returns that doesn't require leaving a big gap at the bottom of the door | Whole house fans, Doors, Return air vent](https://i.pinimg.com/originals/a2/1e/ae/a21eae5b6e4221d1d781d05a03c3c615.jpg)