The vent may be out in the open, but it can also be installed behind the appliance or a door. If you can't find it right away, look around and behind the furnace and check for an access panel. The vent should not be blocked both inside and outside.
Most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the house. Outdoor air enters and leaves a house by: natural ventilation, such as through open windows and doors.
To identify a return vent, turn on the system fan and hold or a piece of paper up — if the vent creates a suction effect on the paper, it's a return vent.
Vents are often either metal hoods or plastic pipes located outside on the side of your house near the ground, though they may also be on the roof or in your attic. You may also find grilled intake vents near or behind your furnace or other gas appliances.
Connect a duct from the outdoors to your HVAC system
This duct will bring outdoor air directly into your return plenum. Assuming your air filter lives at the plenum (not at the return air vent inside your living space), you'll enjoy some filtration of the air before it enters your home.
The best way to find fresh air intake vents is by looking near furnaces and other gas appliances. They usually appear as grilled vents, but they're not always out in the open. If you don't immediately see it, the intake may be behind an appliance, a closed door, or an intake cover panel.
It can be in the form of a hood on an exterior wall. Look for a gray vent hood or a white or black plastic PVC pipe. The fresh air intake leads to a duct that draws air into a vent near the furnace. It's often required in the parts of the home where a gas appliance is installed, except for the garage.
It depends on the car, but the air intakes are almost always somewhere near the front, either below the windshield or somewhere near the headlights. Some rear-engine cars have separate intakes for the hot and cold air, the hot one being somewhere in the engine cooling intakes behind the cabin.
First, shut off the power to the furnace at the circuit-breaker box. Look for your furnace intake pipes, which are often white or black PVC pipes that exit a wall close to your furnace. Find where the intake pipes exit on the outside of your house. They are close to where your furnace is on the inside.
The air inlet should be located high enough above the ground, or roof surface, to prevent accumulated snow from piling up over it, rainwater from splashing into it, and plants from growing into it. It should be located outside, not in an attic, crawlspace, garage, or attached dwelling.
Return vents should be located in centralized rooms, such as larger living spaces or family rooms. These central locations allow return vents to efficiently pull air from the house and into the system. In most cases, you'll find return air vents located on a wall instead of the floor or ceiling.
By installing more return vents throughout your home, they can trap the air and remove it, improving air circulation. A drawback with this method is that your ductwork needs enough space to support additional vents. Smaller homes that can't add more vents need to pursue other options.
Depending on your system and home's construction, builders place these vents in the ceiling, on the floor, under windows, or on exterior walls. Return registers pull stagnant air from the room and send it to the HVAC unit through the air ducts. Some homes only have one return register in a central location.
In most cases, your HVAC system does not pull air from outside when it is heating or cooling your home. Instead, it recirculates the air inside your home. This means it takes the air from inside your house, heats or cools it, and then sends it back into the rooms.
Your air intake is designed to run constantly, brining in a steady flow or fresh air. Some models are equipped with temperature and humidity controls that will turn the unit off if the air coming into the home is too cold, too warm or too humid.
After both equipment and labor, you're likely to pay around $500 to install a basic fresh air intake, but you could pay up to several thousand dollars for more complicated systems.
Often, they will be a set of curved pipes near the foundation of your home, though some systems have the intake and exhaust pipes on or near the roof, in which case you will need a ladder to examine them.
Every home is legally required to have a fresh air intake if a gas appliance, such as a furnace, is installed.
To identify a return vent, take a piece of paper and hold it up to the vent. If the paper is drawn towards the vent, then it's a return vent. Return vents are usually larger than supply vents, and they usually don't have adjustable slats to direct airflow since the air is going into the ducts instead of out.
Checking the Air Filter
Identify the fasteners holding the box together and remove them. These may be a variety of clips, screws, or hex nuts. Once you have removed the top of the air intake box, you should see the air filter. Remove it and visually inspect it to see if it needs to be replaced.
Also, cold air intakes, like the AEM cold air intake, relocate the air box outside of the engine combustion, which allows cooler air to be sucked in by the air filter. Having a performance air filter, like K&N air filters or aFe filters installed allows the cleanest air possible to make its way to your engine.
In many homes the fresh air intake is simply an open duct ran from an outside vent into a basement, or any room housing the home's furnace. Fresh air intakes can be in multiple locations throughout your home, especially in newer homes built to modern building codes requiring homes to be much tighter than older homes.
In short, no. Though in split system air conditioning design, commonly heat pumps, part of your system is located outside your home, it does not take in outside air. Outside air is brought into the system from an intake which is generally located by your furnace but is occasionally its own, separate system.