A fresh air intake vent is required for all furnaces in enclosed spaces, as well as for several other circumstances. For example, it is against building codes for furnaces to draw air from kitchens or bathrooms for combustion.
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.
A fresh air intake allows the HVAC system to pull fresh air from outside and channel it to rooms via specialized vents. Every home is legally required to have a fresh air intake if a gas appliance, such as a furnace, is installed.
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.
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.
Oftentimes, the intake is on the side of the house. 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.
Sliding the dampers manually into a closed position. Turning off a fan switch if the intake is fan-operated. Using the HVAC control panel to automatically close the damper. Turning the lever or knob on an outdoor or indoor unit that says “fresh” or “air intake”.
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.
Walking around your house, you might notice a hooded opening along the side. This is your fresh air intake vent, and it's crucial for the optimal performance of your HVAC equipment. In particular, your heating oil furnace depends on this vent to receive air. Newer systems may have more than one vent.
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.
However, most HVAC contractors use a rule of thumb to determine the number of air vents needed. For example, for a standard residential HVAC unit, you'll generally need one supply vent and one return vent for every 100 to 150 square feet of living space.
Avoid covering an intake with a drape or curtain, or stuffing it with insulation or rags. By blocking it, you could strain the system or, in the case of an intake serving a furnace, cause negative pressure that causes fumes and carbon monoxide to back up.
However, closing the intake vents will cause problems for the ventilation system of your house. It is better to keep intake vents open even in winter times.
With a conventional furnace, a fresh air intake filter is needed so that the furnace does not pull air from what we call “unconditioned” places in the home where air quality is poor. This includes the basement, crawl spaces, attics, even dryer vents. With the filter, the replacement air is drawn from outside the home.
Your furnace will blow cold air if there is no air to heat and send back into your home. Another reason you may not be getting enough air flow is if your ductwork is not sized properly. Unfortunately, this is quite common. If your return ductwork is too small, it will not be able to take in the required amount of air.
A fresh air intake sends air to your furnace and water heater through a duct. Newer homes today use a direct air combustion pipe connected to the appliance. For a furnace, gas appliance, and water heater, having a dedicated air intake can make all the difference for air combustion purposes.
Most newer homes have one or more fresh air intakes to comply with building codes. 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.
There is no pipe to bring outside air in for combustion. Instead, the boiler or furnace draws air from inside the home.
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.
Whenever possible, keep fresh air circulating in your home. Turning on ceiling fans can keep air moving, and combined with opening windows, can help cross-ventilation. A dirty air filter will reduce clean airflow from your home's heating and cooling system.
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.
Without an air filter in place, the engine may also be sucking dirt and debris in at the same time. This can cause damage to internal engine parts, such as valves, pistons and cylinder walls. The result is excessive oil consumption, poor engine performance, and eventually engine failure.
No, an air conditioner does not bring fresh air from outside to the inside of your home. While part of your system may be located outside, if you have a split system, this does not mean it uses the outside air. The primary purpose of your system is not cooling the air; it's to move the unwanted heat out of your air.
The simplest way of bringing in fresh air through the HVAC involves a motorized damper and controller. When the damper is open, it delivers fresh air from the outside to the “return” side of the furnace so that the incoming air can be properly filtered and conditioned before being distributed with the recirculated air.