# Type ! hood dampers



## jeffc (Oct 30, 2013)

Our energy code requires ducts that communicate with the outside to close when the building is not open for business (examples include nights and holidays). I don't want to have a contractor install a barometric damper in a type 1 grease duct but can't find where the IMC prohibits the damper. Can anybody help me with that reference? We are using the 2012 code. Many thanks.


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## cda (Oct 30, 2013)

1. You would have to find one listed for this use

2. Someone would have to assure no grease build up on it

3. Guess part of the listing would be the temperature it works in and it will work with grease on it

Have never seen one


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## steveray (Oct 30, 2013)

What section of what energy code Jeff?


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## Mech (Oct 30, 2013)

I thought there was something in the code that prohibited the use of dampers for type I hoods, but I can not find anything.  What I did find is the following:

From the 2012 IMC:

*506.3.7 Prevention of grease accumulation in grease ducts. *

 Duct systems serving a Type I hood shall be constructed and installed so that  *grease cannot collect in any portion* thereof, and the system shall slope not less  than one-fourth unit vertical in 12 units horizontal (2-percent slope) toward the  hood or toward a grease reservoir designed and installed in accordance with Section  506.3.7.1. Where horizontal ducts exceed 75 feet (22 860 mm) in length, the slope  shall be not less than one unit vertical in 12 units horizontal (8.3 percent slope).

I remember seeing a Type I hood 5 - 10 years ago with manually operated damper plates at the exhaust points on the hood itself.  The exhaust was drawn out the back of the hood and the damper plates slid in a track to cover the exhaust openings into the exhaust duct.  I have no idea if that is legal or not, but that is what was provided.


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## jeffc (Oct 30, 2013)

steveray said:
			
		

> What section of what energy code Jeff?


Washington State uses a modified version of ICC's 2012 energy code. Section CE403.2.4.4 states, Shutoff damper controls. Both outdoor air supply and exhaust ducts shall be equipped with motorized dampers that will automatically shut when the systems or spaces served are not in use or during building warm-up, cooldown, and setback. Then gives several exceptions but none pertain to type 1 hoods.


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## cda (Oct 30, 2013)

from 96::

check """" 9.1 """""""

5.1.6    Listed exhaust hoods with or without exhaust dampers shall be permitted to be constructed of materials required by the listing.

5.1.7    Listed exhaust hoods with or without exhaust dampers shall be permitted to be assembled in accordance with the listing requirements.

7.3.4    For hoods with dampers in the exhaust or supply collar, an access panel for cleaning and inspection shall be provided in the duct or the hood within 457 mm (18 in.) of the damper.

9.1 Dampers.

9.1.1    Dampers shall not be installed in exhaust ducts or exhaust duct systems.

9.1.2    Where specifically listed for such use or where required as part of a listed device or system, dampers in exhaust ducts or exhaust duct systems shall be permitted.

11.1.3    Openings provided for replacing air exhausted through ventilating equipment shall not be restricted by covers, dampers, or any other means that would reduce the operating efficiency of the exhaust system.


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## steveray (Oct 31, 2013)

QUICK....get your patent on listed Type 1 dampers.....$$$$$$$$$


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## fireguy (Nov 1, 2013)

Problems with dampers

1. Most techs do not change the damper fusible links

2. The links are the same temp as the links over the appliances.  They should be lower temps, as the purpose of the damper is so the fire system will trip faster

3. It is difficult to clean both sides of the damper, so it does not get cleaned.


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