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Zero Knievel

Does someone make something like this?

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Ongoing issue with condensation on bathroom AC vents.  These vents are next to ceiling mounted haters/exhaust vents.  They use tubes drawing/dischargeing from/to the attic.  Is there something that could go on the end to close them off when air is not actively being drawn in to blown out to prevent humid air from working its way in?

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Bathroom AC vents...as in, the things that blow cold air in from your AC, right?  They should be connected to ducts that go to the air handler.  They should not be open to outside humid air.

 

Or...something else?

 

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Holy... that's confusing.  OK, so if I'm reading this right, you have condensation on your vents coming from your central AC vents showing up in your bathrooms.  You believe that the combination bathroom vent fan/heater units are the source of your issue.  Most vent fans have a flapper door on them that prevents attic air from backflowing into the bathroom.  If those valves have failed or have been stuck open by insulation, that can cause your issue.  However, I would be more apt to believe that your vent fans are not being used when someone showers to ventilate that humid air out so it just stays in the bathroom and dissipates throughout the adjoining rooms eventually.  But since the humidity is highest in the bathroom, that's where it condensates.  So your issue is probably not with the vent fan, but with the user.

I'm saying all of that because I shower in the front bathroom and the vent fan does not work there.  That also happens to be right next to the central AC unit.  So I have seen this firsthand.  But I have an ulterior motive.  Vent fan doesn't work, and that's the guest bathroom.  You can crap in your own toilet, not mine.

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It’s a heater/vent/light combo in each bathroom.  AC vent is usually within 24 inches of unit in each.

 

Good point with seeing if unit has some kind of flapper valve...that might explain a lot.

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Trying to understand because your post was confusing.  The condensation is on the AC vent and your assumption is that humid air is coming into the bathroom through the exhaust fan/heater/light unit?  If the condensation is only during/after a shower it's not the fan, if it happens all the time or randomly and not related to shower use then it could be the fan unit letting air in.

Edited by superhawk996

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It's happened of late during very humid weather.  If the whole house was an issue, I'd expect to see it on many other vents.  It's just happening in the bathrooms...at the vents next to the ceiling mount heater/vent cluster...which vents into the attic.  We had a similar issue during wintertime when using gas auxiliary heat because gas heat releases water vapor into the air if it's unvented (as is the case with us).

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Bath has the highest humidity, humidity condenses on cold surfaces.

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I know.  I just wonder why they don’t make AC vents that are condensation resistant.

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Lazy product designers, refusing to violate the laws of physics and shit.

 

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When in the bathroom, fan comes on.  Shower or shit, fan should be on.  I'm sure Dave could find out, but this is probably why hotels have all of that on a single switch. 

 

My mom and dad have a heated fan in the back bathroom, came with the house.  Problem is you can't run that fan without the heat, it was wired all together.  So nobody ever crapped in that bathroom unless it was an emergency.  Clearly whoever did that had no clue what they were doing because it popped the breaker within a few minutes.  But if you were freezing, you could go stand in that bathroom and flip the heat on and it would be a sauna before the breaker popped. 

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I think our fans work.  Dunno, have never turned one on.  I guess that's the difference between humid areas and dry ones?  Maybe hotels do that so the shit smell doesn't go into the shared ventilation system?  I'm going to start shitting in the dark in hotels.  And Zero, I still don't fully understand what you're looking for.  A self-closing vent?

 

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2 hours ago, SwampNut said:

Lazy product designers, refusing to violate the laws of physics and shit.

 

It's just an issue with the AC making the vent so cold serious condensation happens when humidity is high.  I don't know how most deal with it.  This condensation happens when nobody's using the bathroom, high humidity (hot outside) and AC is running near all the time..

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4 hours ago, Zero Knievel said:

 

It's just an issue with the AC making the vent so cold serious condensation happens when humidity is high.  I don't know how most deal with it.  This condensation happens when nobody's using the bathroom, high humidity (hot outside) and AC is running near all the time..

 
OK, now we're getting somewhere.  I'm in Mobile, where it's 90% humidity a lot of the time, and I do not have this issue.  It sounds to me like you have a lot of air leaks in the house that is drafting in humid outside air and the system is not able to keep the humidity levels down.  I would check all of the windows and doors to see if you have air coming through there first, which is easily fixed with new seals on the door jambs or caulking the windows.  I would also check the AC ducting in the attic to make sure you don't have a gap that is blowing cold air into the attic and also allowing hot, humid air into the ducts when the system is off.  When that cold air starts blowing again, that's going to condensate in the duct and blow it towards the vent.

 

You also need to check your return on the central AC.  On my house, the return was not sealed to the living space, and was drawing hot attic air from between the studs and through the AC system (not only is that unfiltered air, it's also 100+ degrees and the system has to work extremely hard to cool it.)  That is also drawing in outside humid air instead of recycling the lower humidity air in the house already.  Another thing to check is the seal between the central unit and the return itself.  In my house, it's a closet with the return at the bottom.  The AC guy showed me by closing the door and the AC system sucked the door in and slammed it shut.  Your door should not move at all.  If it is sucking it closed, that's also bypassing the filter and can draw air from any gaps between the top of the unit and the attic when the door is shut.

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I’m pretty sure the issue is humid air getting in via the ceiling vent in the bathrooms.  Hence why I’m wondering if someone makes a thing that blocks air flow when it’s not running to keep outside air from coming in.  I suppose I have to get up in the attic and have someone work the vent then the heat to see if the vent hose flows both ways.

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Do you mean like a dryer or rangehood vent? They have "flappers" to prevent air (and mice and bugs) from getting back in when the blower isn't running. Also, did I read correctly that your bathroom fan vents into the attic? That's not right and they should be at least vented to the eaves but ideally outside. Maybe I'm missing the problem here but I read through the posts twice.

 

 

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On 7/30/2019 at 11:51 AM, Furbird said:

I'm sure Dave could find out, but this is probably why hotels have all of that on a single switch. 

 

In most hotels the vent is permanently on...no switch.

 

We don't normally rely on humans to care about mold issues, peeling paint, wallpaper....after they leave :)

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29 minutes ago, Biometrix said:

Also, did I read correctly that your bathroom fan vents into the attic? That's not right and they should be at least vented to the eaves but ideally outside. Maybe I'm missing the problem here but I read through the posts twice.


I've never seen a bathroom fan that vents to anything but the attic.  Range hoods vent externally (or through a filter/trap system and recirculate inside) but not bathroom fans.

 

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2 hours ago, Furbird said:

I've never seen a bathroom fan that vents to anything but the attic.

How to Properly Vent a Bathroom Exhaust Fan in an Attic

By: Danny Lipford
 

Bathroom exhaust fans perform an important function by removing excess moisture from your home. When venting a bathroom exhaust fan, make sure to vent the air to the outside, rather than into your attic where it can cause mold and mildew to form.

Options for venting a bathroom exhaust fan include (best to worst):

  1. Through the roof or an exterior gable wall.
  2. Behind a gable vent.
  3. Behind a soffit vent.

To improve venting and reduce air resistance in the vent pipe:

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I didn't say it was right, I said that's the only way I've seen it done.  The irony that Danny Lipford is from here is not lost on me either.  IMO it's the tradeoff of cutting a hole in your roof to vent a bathroom in one of the rainiest cities in the US that is also in a hurricane-prone area with multiple months of 90+ percent humidity, versus venting it into the attic that should have enough cross-flow ventilation or forced ventilation to dissipate or remove said bath fan exhaust humidity before it becomes a problem.

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If your bathroom has a exterior wall you can go through the ceiling and out the eve.  But I get your point.

Edited by blackhawkxx

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Attic is open to outside air...well-vented.  However, that means the outside humidity is in the attic space.

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