Bathroom fan vented into NOTHING


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Old 12-24-16, 09:35 PM
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Bathroom fan vented into NOTHING

House was built in 2002; rambler style with 18 foot cilings at some points. Upstairs bathroom (not master) also has a shower. I've noticied the fan doesn't do well to vacate moisture. Was in the attic today inspecting the pipe, etc, and found the fan under 12 inches of blow insulation...just venting into the insulation.

Darn contractors.

My question to the forum is such: I'm running 4 or 6 inch (insulated) pipe from the new fan I'll install. The question is do I vent up to the roof or to the soffit? I know code in Utah, where I live, changed about 8 years ago where new construction doesn't let builders vento the soffit anylonger. I guess that can cause moisture to blow back into the attic when the fan is in use and there is typical soffit updraft.

I can go to the roof; will use a contractor to install the vent for me. Or I can try to go to the soffit and cut into that for an exterior vent. I think roof is the best way, just not a fan of another roof vent--if I can avoid it.
 
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Old 12-24-16, 09:39 PM
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Definitely best to go thru the roof. Determine the size needed and hire a roofer.
Well worth the few bucks.

Actually a pretty common and unfortunate problem.


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Old 12-25-16, 05:35 AM
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The roof may be your only choice since you don't have gables. The gable end would be the preferred choice. I just don't like poking holes in an otherwise non-leaking roof. It can bite you. There are soffit vents made to keep air feedback down, so you may want to look into them as well as an alternative.

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Old 12-26-16, 02:59 PM
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Thanks for your thoughts. One last follow-up question.

I have the one fan for the bathroom with shower (that I spoke of previously). I also have a master bathroom with an under powered fan. The master bathroom is 150 Sq Ft; the central bathroom and shower is only 60 Sq. Ft.

I've decided on replacing both bathroom fans for better flow. The master will get a fan that is 150 CFM and it comes with a 6 inch connection, that can be moved to 4, but I want to keep it at 6 for best possible flow. The other bathroom will get an 80 CFM fan that has a 4 inch connection.

My thought was to buy 12 feet of the 6 inch insulated ducting and just use it for both.

To my question, can the 4" be connector to a 6" without a major hassle? I figure the ring clamp I will be using can just hold the pipe tight to the vent and the fan. This would save having to buy 4 and 6 inch insulated duct work.

By the way, I have a trusted roofer coming out next week to repair an issue on the other end of the home. I'll ask him to install both vents on the roof for me, thus avoiding the soffit vent.
Thx.
 
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Old 12-26-16, 04:02 PM
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You can't combine the piping from the two bathrooms. The potential of back wash of air from the active bathroom to the inactive bathroom is too great. You will need to run separate lines.

NOW if you were to install vents in each bathroom and ran the two lines to a wye, connected to an inline booster fan ahead of the wye, it may pass the muster. You just can't "push" the air. You would have to install a relay type switching from each bathroom to the fan, however so it will work independently.
 
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Old 12-26-16, 05:22 PM
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Sorry. I wasn't very clear.

2 bathrooms. Each its own piping to the roof. However, I would like to use 6 inch on both, even though one will be running a fan that has a 4 inch connection and the other a 6 inch. The question is could 6 inch piping (insulated) fit the 4? Don't want to buy two different types of piping, if I can avoid it.
 
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Old 12-26-16, 05:48 PM
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Sure. You can buy a 6" to 4" adapter. You won't experience as much volume with the smaller fan.
 
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Old 12-28-16, 01:43 PM
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FYI - some good points made in this video: https://youtu.be/K3vM4i31Y40
 
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Old 12-28-16, 05:35 PM
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One thing to consider being that you are in UT is the snow covering the vent,I have that problem in northern NH.usually have to clear them a few times with a roof rake.
Geo
 
 

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