Exhaust Ventilation

Exhaust Ventilation Systems Are Simple and Dependable

UPDATED March 1, 2014

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Exhaust Ventilation, including:

  • Design and build strategies
  • Necessary codes
  • Application how-tos
  • Using materials

Exhaust fans are the easiest way to provide mechanical ventilation for a house

Choose a quiet fan that's not too powerful
Exhaust fans are rated for both the volume of air they move per unit of time (measured in cubic feet per minute or cfm) and the amount of noise they make (measured in sones, where the lower the value the quieter the fan).

An exhaust ventilation system does not need a powerful fan. According to the requirements of ASHRAEAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). International organization dedicated to the advancement of heating, ventilation, air conditioning, and refrigeration through research, standards writing, publishing, and continuing education. Membership is open to anyone in the HVAC&R field; the organization has about 50,000 members. Standard 62.2, a 2,000-square-foot house with three occupants requires only 42.5 cfm of mechanical ventilation.

Oversized fans waste electrical energy and space heat. If they are very powerful, they can cause ...

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Fri, 10/05/2012 - 05:28

Response to Denis Recchia
by Martin Holladay, GBA Advisor

It look like you posted the same comment and questions in three different places. To avoid multiple postings, all of the answers will appear here -- on the Q&A page.

Thu, 10/04/2012 - 19:14

Humidity Problems
by Denis Recchia

Hopefully I can get myself out of this mess I got myself into :)

I recently built a pretty tight house with my old fashioned dad, I think we ended up doing a pretty good job with making the house tight, but didnt include any mechanical ventilation in the home. Right now in early october we are seeing relative humidity levels around 75% with temperatures inside of around 70 deg F.

How can I fix this? Should I install exhaust fans in the two bathrooms upstairs? My Dad says open a window, but its going to be winter very soon, and recently its been raining so much the humidity is worse outside than inside.

Im moved into the house, so any mechanical ventilation i pick im sure is going to be a disaster. The home is double 2X4 walls with a 2 inch layer of closed cell foam with 10 inches of cellulose inside of it.

Thanks in advance,


Fri, 04/23/2010 - 16:52

Exhaust Fans Accessories
by Anonymous

Help me. Condo has no stovetop exhaust fan ventilation! Any way(s) to cope with this? Set off smoke detector in past.

Thu, 10/08/2009 - 19:26

by Peggy Deras

There is a safety issue about range hood exhaust fans that is not addressed in your article: Remote, and in-line blowers used in conjunction with a range hood fail miserably in the event of a fire on the cooking surface. The flame is pulled up through the hood and into the ductwork, quickly burning through and into wall, attic and roof.

A range hood with a squirrel cage fan mounted within the hood canopy will stop flame at the fan, giving precious seconds to fight the fire on the rangetop.

Grease fires are the most common residential fires.

If you are confronted with such a fire, do not use an extinguisher or water.
Instead, get down low and turn off the flame under the burning pot or pan.
Then grab a towel and wet it at the sink and throw it over the pan.
To see this exercise on video:

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