2 vents on the side of chimney

[Peter Louis]

Hi, Guys
A couple days ago, when I passed by a house. I found there are 2 vents on either side of the framed chimney. They are as same as the dryer vents. I do not know what they are. are they make-up air inlets? Sorry, I did not take the pics. anybody can help?

Thanks

[H.G. Watson, Sr.]

Yes they may be fresh air/combustion air intakes for a pre-manufactured wood burning fireplace, for example.

http://www.inspectionnews.net/home_inspection/attachments/fireplaces-chimneys-solid-fuel-burning-appliances-home-inspection-commercial-inspection/20973d1296177854-fireblocking-material-firebreak1.jpg

2nd Might also be for an air kit or a reburn unit or cat. converter.

Need an outside air kit with tighter, more energy-efficient, better insulated, tightly-constructed and less infiltrated construction.

Heatilator Fireplaces - Products Wood Burning Fireplaces - Wood Fireplaces (http://www.heatilator.com/products/fireplaces/woodFireplaceDetail.asp?f=Constitution)

[Peter Louis]

Great, Thank you.

[Bob Harper]

Some large boxes actually require 2 combustion air intakes and some also require a "chimney air kit". This is an air kit to bring cold outdoor air directly to the base of the air cooled factory chimney. For some, it is optional while some actually require it. The commonalities are they appear to be dryer vent jacks but lack backdraft dampers and do have screens.

Combustion air intakes generally cannoy be located above the point they enter the firebox. I got HHT to get UL approval of pulling air from above the fireplace as long as:
-it has a trap at the base
-is made of metallic hose only
-cannot originate within 3 ft vertially of the flue gas outlet
-is properly firestopped at each floor level. Most AHJs require 12" rigid metallic pipe above and below each firestop such as 26ga. galvanized steel stovepipe.

HTH