Whole House Fan exhaust venting


  #1  
Old 07-06-04, 03:56 PM
klmathews
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Question Whole House Fan exhaust venting

I have installed a Dalton 36" WHF rated at 10,000 CFM and requiring 12-13 sqft exhaust venting. I have 4 gable vents and 8 soffet vents for a total of about 5 sqft.

I still need 7+ SQFT to exhaust this house fan.

My main goal is to minimize the number of holes I have to put in the roof.

One option I am considering is a powered roof vent that is rated at 1500 CFM and requires 5.0 sqft free air intake.

My question: when I consider the powered roof vent should I be comparing the CFM in and out (about 15% required) or the free air intake (about 70% required)?

I have also considerd Rige vents, Turbins, even building a dormer over the fan area.

An suggestions would be appreciated.

Keith
 
  #2  
Old 07-06-04, 05:40 PM
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when i was a kid "up north" we always had one. dad installed both of the ones i remember and did not add any vents, (i called and asked him)

in your case i would first find out how many amps the motor is pulling and compare it to the nameplate. does it state the static pressure the fan runs at?

that is a LOT of cfm, if the motor is multispeed, what you have may be enough if ran in low or medium speed
 
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Old 07-06-04, 11:17 PM
klmathews
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The motor is a two speed motor. but the slow speed is not adaquate to get the air changes through the house.

running the fan with inadiquate venting not only reduces the efficiency of the fan, it also puts additional strain on the motor reducing it's life, and the back pressure in the attic is compressing all the blown-in insulation.

I have to add venting, the question is how.

I will check the the current of the motor at high speed. The full load rating o fthe motor is 8.7 amps.
 
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Old 07-08-04, 12:23 PM
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Wink

What works real well is build a good looking cupola up there in the center of the roof, To lets this air out and also the attic air. You can put a wind vane on it



ED
 
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Old 07-09-04, 04:31 PM
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saw one today

did not have much in the way of ventilation in the attic, 1 gable, some soffit vents...

homeowner said it worked great, 12 years now. what is the static pressure rated for on that fan, that could make a difference
 
 

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