How to Use a Combustion Air Intake
Homes need to breathe. Fresh air is needed for combustion in furnaces, fireplaces, wood stoves, gas water heaters and clothes dryers. As people make their homes more energy efficient by sealing cracks, adding insulation and doing other things to prevent heat loss, homes can become starved for air. This is especially true when you're using exhaust fans and vented appliances which draw more and more air from inside the house; air from the outside can be pulled into the home, possibly down the furnace vent or fireplace chimney. This is called "back drafting" and can cause carbon monoxide (CO) to form.
CO is a colorless, odorless gas produced when fuel is not burned completely. Automobiles, charcoal or wood fires and improperly vented or air-starved coal, oil and gas furnaces can produce CO.
Be aware of these CO signals:
• Headaches, nausea, dizziness
• Excessive humidity, heavily frosted windows
• Fireplace smokes, won't draw
• Furnace vents back drafts (See Fresh Air Check below.)
To prevent homes from becoming starved for air, the Uniform Mechanical Code requires that all new homes be built with a special duct that brings outside air directly to the heating system. All furnace and boiler installations in existing homes are also required to have a combustion air duct.
To determine if your home is receiving sufficient fresh air:
1. Close all doors and windows.
2. If you have a fireplace(s), build a fire. Wait until the flames are burning vigorously.
3. Turn on all exhausting devices, such as:
o Kitchen and bathroom exhaust fans
o Dryers (gas and electric)
o Attic fans
4. Turn on all exhausting devices, such as:
o Heating equipment
o Water heater
5. Turn on all vented gas appliances, such as:
6. Wait 10 minutes for drafts to stabilize.
7. Hold a lit match below the heating system draft hood air intake (see illustration at right).
o If the match remains lit and the match flame pulls toward the draft hood, this indicates sufficient fresh air. Check draft hoods on all other equipment also (gas space heaters, water heaters and additional heating systems). Return appliances and exhausting devices to their original condition.
o If the match goes out, it means the vent may be plugged and/or the air supply in your home may be inadequate.
o Check for plugged vent connectors and chimneys. Repair stoppage and test again.
o If the match goes out even when vent is clear, additional air must be brought into the structure from outside. Refer to the Uniform Mechanical Code or contact a qualified heating contractor or your local gas utility service department.
If your house is starving for air, a vent or fresh air intake needs to be installed directly to the furnace area; until it is installed, limit use of clothes dryers, fireplaces, furnaces, and mechanical exhaust fans. Operating more than one of these devices at a time can contribute to back drafting if your home doesn't have an adequate fresh air supply.
Materials used for ducting must meet standards described in the Uniform Mechanical Code. Flexible ducting is not recommended because ridges create turbulence which reduces air flow. Before installing a duct, check with your local Building Codes office for size and materials. Here are example of installations of fresh air ducts.
Duct Supplying Outside Air to Floor in Furnace Area
1. Be sure duct is sized in accordance with the Uniform Mechanical Code.
2. Place the outside air intake duct (A) at least one foot above grade level.
3. Cover the air intake with ¼” mesh screen and hood.
4. The duct must discharge the fresh air at a level no more than one foot off the floor.
As you understand it’s very important to have combustion air intake also from energy saving pint of view, especially if you have a mechanical room. The idea behind this is you don’t using conditioned air as the combustion one. Also it’s important to bring the combustion air to the water heater or furnace as close as possible. If you need explanation how to install a Combustion Air Intake, just push a PayPal button below, follow the instructions and I will release the special page where I'm explaining how to do that.
Combustion Air Intake
This page gives a description of installation of the Combustion Air Inake which is necessary element in your HVAC system. On this page you can see pictures of all necessary tools and materials and pictures of the Combustion Air Inake installed. There are 18 pictures on the page. All installation is divided into five steps which represent an entire project in the making.