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.
To find a fresh air intake, look for a grilled vent near a gas appliance. 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.
Most boilers and furnaces are combustion appliances, meaning they burn fuel like natural gas, oil, or propane in order to generate heat. But the combustion process also requires air. Depending on how your heating system was installed, it may draw air from inside your home for combustion, or it may use outside air.
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.
Your exterior furnace exhaust pipe is typically located on your home's sidewall, although it can be found on your home's roof in some cases. If you need help with locating it on the roof, please schedule an inspection with your nearest plumbing HVAC contractor.
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. You can also follow the air intake vent to its source, whether it's the attic or a location on the exterior of your home.
Unblocking a Furnace Intake Vent
A small brush is usually enough to clear debris off the screen. For more stubborn buildup, you can use a shop vac, but that usually isn't necessary.
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.
If you just have a "regular" HVAC system, running the fan will pull from the return air vent (s) which are somewhere in the conditioned space of your house. To pull outside air you'd need something like an ERV that is specifically designed to draw outside air.
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.
Remove the vent cover and use a vacuum or a soft-bristled cleaning brush to remove any visible excessive dust or debris. For a more thorough cleaning, soak the vent cover in warm soapy water and rinse it off thoroughly. Once it is completely dry, replace the vent cover and turn on the HVAC system.
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.
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.
Blocked outside furnace vents could cause carbon monoxide to build up in your home, potentially resulting in carbon monoxide poisoning. A blocked vent also can affect the performance of your furnace, which may not run properly or not run at all when the intake or exhaust vent is blocked.
The engine's combustion relies heavily on air, which mixes with fuel to generate energy. In the absence of a sufficient quantity of oxygen, an engine will not be able to generate power, and it may not even start. Whenever the air filter in your car's engine becomes too clogged, it may start to misfire.
Quick Highlights of Furnace Drain Issues and Fixes
Clear blockages using a wet/dry vacuum at trap inlet and outlet points to remove accumulated debris and sludge. Pour mixture of baking soda and vinegar through the drain system, followed by hot water to dissolve mineral deposits.
Every home is legally required to have a fresh air intake if a gas appliance, such as a furnace, is installed.
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.
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.