Furnace combustion air from attic

Combustion air from outside can be supplied by a single opening located within 12 of the ceiling. A combustion damper allows air to pass from the outdoors to your attic whenever the furnace turns on.

The Problem Of Getting Air For Atmospheric Combustion Appliances Energy Vanguard from www.energyvanguard.com

Assuming your combustion air requirements are sufficient install weather proofingstripping around the furnace room door to contain the cold air within the furnace room.

Furnace combustion air from attic. Combustion air being supplied from the attic space is allowed. But there should be two sources. At ceiling and floor.

Heat shield fire break is required at the exhaust B-vent. Cfoley1 Christopher Foley February 23 2014 1129pm 3. The combustion air intake should be piped to the attic or where the exhaust terminates.

Using indoor air for combustion is a common shortcut. Converting the furnace to sealed combustion should greatly reduce noise. When you say high efficiency is it already a sealed combustion plastic intake and exhaust.

A combustion damper allows air to pass from the outdoors to your attic whenever the furnace turns on. When installed correctly the damper provides the right amount of air for the combustion process. It lets the furnace work properly without increasing the risk of CO backdrafting.

The furnace has the option of drawing combustion air from the living space according to the directions with typical conditions of course. The attic has 300 feet of vented soffit plus ridge vent. Im going to go out on a limb a bit and say there may even be an advantage to doing this.

Lets say you have a well sealed air barrier and good. Both say the same thing about using indoor air for combustion. The space that the atmospheric combustion air can draw from has to have at least 50 cubic feet of volume for each 1000 BTUhour of appliance capacity.

Lets say you bring the attic inside the building enclosure by putting spray foam insulation at the roofline the case with the two furnaces in my previous article on this topic. There are two basic ways for your furnace to get its combustion air. Most high efficiency furnaces get their combustion air directly from the outside.

This is the best and most efficient way to do it. If your furnace has two PVC pipes going to the outside then one of those pipes is taking the flue gases out and one is bringing fresh air in for combustion. This is called a direct vent furnace.

When combustion air is supplied from outside Ventilated AtticCrawlspace. Single Permanent Opening to Outside. Combustion air from outside can be supplied by a single opening located within 12 of the ceiling.

The openings must communicate directly with the outside and can be through a. Combustion air can only be drawn from the attic when it is adequately ventilated with a source of outside air. Think about how much air would leave this sealed attic with a negative pressure in the area below it.

Additionally the air sucked in from your attic and other similar sources also typically contain a higher level of contaminants with corrosive properties which can cause the corrosion of parts inside the combustion chamber of your furnaceespecially the heat exchangers and the burners. This reduces the lifespan of the furnace. 2 Relocate your fresh air intake combustion pot near the furnace.

Frame and close off the furnace room. Assuming your combustion air requirements are sufficient install weather proofingstripping around the furnace room door to contain the cold air within the furnace room. First of all its always a bad idea to put a furnace in an attic.

But you probably already know that. One major problem is providing enough combustion air for the furnace burner. I hope that this is a sealed combustion furnace with a combustion air duct that pulls combustion air from the outdoors.

M17033 Attic combustion air. Same basic rules apply two ducts are needed and the attic must be able to supply the required volume of combustion air. The ducts must extend a minimum of 6 above joists or insulation.

The duct ends cannot be screened. All furnaces require requires what we call in the trade combustion air. This means a supply of air to burn with the Ngas to produce heat.

With an open not foam sealed attic that combustion air can come in from the eves andor vents. With a foamed or sealed attic there is no place for the combustion air to come in. Typical airtight woodstoves require only 10-25 cfm of combustion air - much less than an open fireplace 50 to 150 cfm or more or to older non-airtight woodstove.

But in tighter homes it may be necessary to provide combustion air or a draft inducer fan even for these appliances. Fresh combustion air for the furnace is coming from the soffit vents from both roofs. The furnace has a stack which penetrates the flat roof and is about 3-4 above the roof plane.

However the furnace is in an attic space which has no venting for warm humid air from house from soffits from hot roof etc to escape. Why in the discussion of attic retrofits gas furnaces does the conversation always focus on the combustion air the furnace needs to operate and never seem to hear about the safety side of it. The scary fact is that you have a unit that is emitting carbon monoxide and yet there is no concern about the safety of the building occupant.

A furnace is a forced-air system which is the most popular type of HVAC system installed in homes. Some furnaces are built with a downflow design. In a downflow furnace cool air is pulled downward to the combustion chamber where its heated.

This type of furnace works best when placed in the attic. The airflow is taken advantage of. In an attempt to reduce costs some contractors do questionable retrofits on attic furnaces.

This horizontal low-boy furnace in a sealed attic has a combustion air duct taped to the furnace cabinet. Not only does it violate the building code it may not. Typical gas furnaces and water heaters need combustion air from the surrounding area in order to operate properly and safely.

If they dont get it they can leach carbon monoxide into your living space. Thats one reason among others that most attics and crawlspaces are vented to the outdoors. Can furnace combustion air be pulled from attic.

I just read the installation manual of a new Goodman 96 efficiency gas furnace and Im going to pull combustion air from the attic as the preferred source. No one commented on the increased efficiency that will result because attic air is going to be somewhat warmer than outside air. Combustion Air 1 Air that is supplied to combustion appliances to be used in the combustion of fuels and the process of venting combustion gases.

Inadequate combustion air can lead to dangerous problems. 2 The duct work installed to bring fresh outside air to the furnace andor hot water heater. Normally 2 separate supplies of air are.

When the furnace is installed in an attic or other insulated space keep insulation away from the furnace. When the furnace is installed in non-direct vent applications do not block the furnace combustion air opening with clothing boxes doors etc. Air is needed for proper combustion and safe unit operation.