How to Install A Fresh Air Intake for Your Furnace


How to Install A Fresh Air Intake for Your Furnace

A fresh air intake is one of the most crucial components to any HVAC system. It helps the HVAC system maintain a comfortable, safe environment for your home. Understanding what it is and what it should do for your home is important.

To ensure that air flows properly throughout your home, the installation needs to be performed properly. With a step-by-step installation guide, you will get the proper fresh air intake for your furnace so that everything can run properly.

What is a Fresh Air Intake?

The name is pretty self-explanatory. This is a path in your ductwork that allows fresh air to come into your home from the outside. In most homes, this is something like an open duct that runs from a vent located outside into a basement or wherever the furnace is located.

Even better, fresh air intakes can be located in several spots throughout the home. New homes will often have these because the building codes are much stricter than they were for older homes. Homes are now built to reduce the amount of lost air and increase energy efficiency. This is helpful for older furnaces, too.

Just as important as increasing energy efficient is the fact that it can have an impact on your health. There are pollutants in the air that can actually be attracted to older homes. The basement, attic, and crawl space can be particularly susceptible. No one wants to have to bring in a repairman to make the issue better.

Installing the Intake

The furnace ducts in the home distribute warm air. Using those fresh air ducts, they take in fresh air, heating it up in the furnace and distribute them throughout the ducts. Installing the intake the right way is important to ensure proper airflow.

Step 1: Choose a Spot

Before you can start, you will want to choose the proper spot for your intake hood. You want to choose a place that is away from where the furnace, the exhaust, and the dryer vents are. These will run into the home, typically in the basement.

You need a separate entry point for a very important reason. If they are left too close together, it can wind up recirculating suffocating gases throughout your home. We definitely want to avoid doing that, so pick a spot for the hood that is located away from those vents.

Step 2: Install the Intake Hood

Using a hole saw, drill out a hole and then slowly push the pipe above where your fresh air intake hood is located. You will then tighten your inlet hood to the walls using screws that are meant for wood exteriors.

When you have finished hanging the intake hood, use a high-quality caulk to seal the gaps. It should be an exterior caulk so that it seals properly and can stand up to daily wear and tear. Make sure the space is clean and dry before applying the caulk.

Step 3: Creating a Hole in the Return Duct

With a pair of aviation snips, you need to make a hole that is about 6 inches wide inside of the return duct. Make sure that you have located the hole to be adjacent to your furnace pipe. Make sure to space this carefully.

When you have the hole in place, you will need to install the metal collar. This is what allows the pipe to sit inside of the hole. Check to make sure the metallic collar is as stable as it can be before moving on to the next step.

Step 4: Installing the Duct

After properly getting the hood in place and drilling a hole for the return duct, you are now ready to install the duct itself. You will want a galvanized duct for the best durability. Place that duct between the pipe that is coming from the collar and inlet lid.

If a joint cut is necessary, you can use a crimper on the pipe in order to properly fit in the joints. Just make sure that the joints you use are fixed in place properly. If they aren’t, the fresh air will not circulate properly.

Step 5: Installing the Barometric Damper

The barometric damper is what gets installed to prevent that fresh air from going into the duct before the furnace is fully functional. The damper is actually directly installed into the intake hood but make sure to follow these steps precisely.

Make sure that when you install the barometric damper, you keep the arrows of the damper pointed towards the furnace. By having the arrows lined up properly, it means that the fresh air will flow properly in the direction of the furnace as it should.

Step 6: Hanging the Duct

Now comes time to install the galvanized duct. This duct hangs thanks to the support of a hanger strap. Just makes sure that when choosing a hanger strap, you choose one that is galvanized. Choosing a galvanized hanger strap means that it will have the tensile strength required to hold up to the tension as well as any temperature changes that will take place in your area.

Do not go with a cheap hanger strap. The last thing that you want is for the duct to fall because the strap broke under the tension of the weight.

Step 7: Make Sure it is Airtight

The last step in the installation of your fresh air intake is to ensure that your duct is airtight. To do this, you will want to caulk every joint of the duct. The duct can be insulated even further if you use a duct wrap; this can be foil but there are other duct wraps.

The duct wrap is to ensure that the duct won’t sweat when the cooler air hits. It will also ensure that your duct is airtight and protected from any inefficient air leaks.

Why Do Furnaces Need Fresh Air?

The short and simple answer is that they need oxygen. It is a key component when it comes to combustion, so your furnace needs that air. A gas furnace will need 30 feet of air for each foot of gas that gets used.

To give you a better idea of what that means, it is about the equivalent of running the exhaust fan in your bathroom into the furnace’s combustion chamber.

Furnace Efficiency

Most furnaces are known as “80 percent furnaces”. This means that 20 percent of the possible energy that is found in natural gas, which is then used for heating, is lost in the process of combustion due to the venting involved. They have a rating of 80 when it comes to annual fuel utilization efficiency (or AFUE).

There are also “90 percent furnaces”. These are high-efficiency furnaces because they only allow 10 percent of that possible energy to be lost due to venting during the combustion process. Being able to cut that lost energy in half means more of it is getting used instead of being wasted. Naturally, they have a rating of 90 on the AFUE scale.

Air Quality

Perhaps one of the most important reasons to have consistent fresh air flow is to improve overall air quality. We need to breathe. There is no workaround for that so we need to make sure that the air we are breathing in is as clean as it can be.

With an inefficient fresh air intake, you could be breathing air that is littered with pollutants. This will lower the overall air quality and could actually lead to breathing problems if nothing is done about it over long periods of time.

Ryan Womeldorf

Ryan Womeldorf has more than a decade of experience writing. He loves to blog about construction, plumbing, and other home topics. Ryan also loves hockey and a lifelong Buffalo sports fan.

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