Interpretation #7112

Published November 28, 2012

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Original Request

Code Version
2010
Code
MECHANIC
Code Description
Mechanical
Chapter
5
Section
505.2
Topic
automatic control

Question

Is it the intent of this section when it says "automatically controlled" is referring to a "motorized" means of closure?

Answer Published 11/28/2012 at 9:34 PM

No. The requirement is for the supply
of make-up air to be automatically
provided when the exhaust hood is
operational. This could be through
gravity or mechanical means, as long as
it opens and closes when the exhaust
fan is in operation without the need
for the use of manual controls by the
user.

Commentary

One possible method would be to provide a gravity operated backdraft damper which is forced open by the negative pressure of the fan and automatically closes when the exhaust fan is not in operation.