Downdraft Vent

Originally Posted By: rwashington
This post was automatically imported from our archived forum.



Is there a code for a downdraft vent when it is coming out of a post tension slab that it cannot use a 90 degree elbow but rather is allowed only a 45 degree? I have a picture and one of these days I will figure how to post it. icon_biggrin.gif


Originally Posted By: dvalley
This post was automatically imported from our archived forum.



Richard,


I'm not sure what you're asking.

Here's a tutorial for posting pics...
![](upload://me4MtRe3nGBGET8vgZY42XGj9kl.gif)


--
David Valley
MAB Member

Massachusetts Certified Home Inspections
http://www.masscertified.com

"Some cause happiness wherever they go; others, whenever they go."

Originally Posted By: escanlan
This post was automatically imported from our archived forum.



Quote:
M1502
RANGE HOODS
M1502.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct. The duct serving the hood shall have a smooth interior surface, shall be air tight and shall be equipped with a backdraft damper. Ducts serving range hoods shall not terminate in an attic or crawl space or areas inside the building.
Exception: Where installed in accordance with the manufacturer's installation instructions, and where mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.
M1502.2 Duct material.
Single-wall ducts serving range hoods shall be constructed of galvanized steel, stainless steel or copper.
Exception: Ducts for domestic kitchen cooking appliances equipped with downdraft exhaust systems shall be permitted to be constructed of schedule 40 PVC pipe provided that the installation complies with all of the following:
1. The duct shall be installed under a concrete slab poured on grade,
2. The underfloor trench in which the duct is installed shall be completely backfilled with sand or gravel,
3. The PVC duct shall extend not greater than 1 inch (25.4 mm) above the indoor concrete floor surface,
4. The PVC duct shall extend not greater than 1 inch (25.4 mm) above grade outside of the building, and 5. The PVC ducts shall be solvent cemented.
M1502.3 Kitchen exhaust rates.
Where domestic kitchen cooking appliances are equipped with ducted range hoods or down-draft exhaust systems, the fans shall be sized in accordancewithSectionM1506.3.