Drafts from bathroom exhaust fans

[m123]

I can feel cold air coming in from my bathroom exhaust fans. I open my microwave and the inside feels cold from a draft coming in from the outside exhaust vent as well.

I know there are the factory dampers on the ductwork, but they obviously don’t work the best.

Does anyone have suggestions on sealing these better??? Is there anything out there than these cheap flapper type dampers? Willing to pay more for something that actually works well.

If it matters, all my ducts are 4”




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[bored350]

I have 2 of these, one for each bathroom fan. Notable improvement after installation.

https://www.finehomebuilding.com/2016/12/07/passive-backdraft-dampers

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[LB-1911]

^

Runs 1:29
Cape Backdraft Damper

 

[Richard Cranium]

check your damper, you should have one on the outside of your house where it exhausts plus most also have one right after the fan.

 

[nh_yota]

The vent fan in my downstairs bathroom had a draft for years until I figured out that the air wasn't coming in through the exhaust vent but was coming in through a gap between the fan housing and the ceiling drywall. I pulled the cover off, sealed up the gap with foil tape and the draft stopped for good. That part of the house is a single story so there is just a small unconditioned attic above the bathroom and that's how the cold air was getting inside.

 

[Bretny]

What type of heater do you have? If its anything with a chimney that dosnt have a make up air tube it will pull air from any crack in your house. Bath vent and microwave vent being the easiest.

Personaly i wouldnt bother venting the over the stove microwaves and i havnt in my house. Just allows for another hole,air leak in the house. Unless your making maple syrup in your house there really not needed.

 

[climb.on]

Just allows for another hole,air leak in the house. Unless your making maple syrup in your house there really not needed.

I would strongly debate that. Most people should have one that works well. in the 300-600cfm. Air quality inside the home, especially newer & tighter homes is a huge issue and is oven overlooked leading to excessive condensation on windows, stale unhealthy air we breathe, mold in our walls and a generally more comfortable living space.

Unless:
1. you have a really old leaky house (basically a really inefficient air exchanger)
2. have a fancy carbon recirculating filtration fan above the range, AND and well deigned air exchanger.
3. you never use your stove.

 

[RoadBeater]

I have 2 of these, one for each bathroom fan. Notable improvement after installation.

https://www.finehomebuilding.com/2016/12/07/passive-backdraft-dampers

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Interesting, I'm researching backdraft valves, as I am going to put new fans and piping in my two bathrooms. I had seen this one, but couldn't find anyone that had used it. Does it keep the bugs out also? I'll be putting a soffit vent, so king of concerned about having bugs find their way into the bathroom.

 

[couch67]

I find the wall mounted exhaust vents with the single flap work best for backdraft prevention, the louvered ones are way too drafty.

HD carries the metal ones with a grill to keep the critters out.

 

[bored350]

Interesting, I'm researching backdraft valves, as I am going to put new fans and piping in my two bathrooms. I had seen this one, but couldn't find anyone that had used it. Does it keep the bugs out also? I'll be putting a soffit vent, so king of concerned about having bugs find their way into the bathroom.

It will do nothing to keep bugs out, only stop back drafts. What you also want to use with this is Panasonic's soffit vent and be sure to use solid duct from the fan to the vent. It is what will keep the bugs out while maintaining the best flow volume

https://www.finehomebuilding.com/2018/02/09/soffit-vent-solution

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[RoadBeater]

It will do nothing to keep bugs out, only stop back drafts. What you also want to use with this is Panasonic's soffit vent and be sure to use solid duct from the fan to the vent. It is what will keep the bugs out while maintaining the best glow volume

https://www.finehomebuilding.com/2018/02/09/soffit-vent-solution

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I did see that one on my search. That looks perfect for a new build, but not sure how easily I can retrofit to my application. I was thinking about putting a hole up in the soffit, then fishing the elbow and pipe up to the attic, then connect to the fan. both of the fans are less than 5' to the outside wall, so I don't think the duct will be much resistance.

 

[Bretny]

I would strongly debate that. Most people should have one that works well. in the 300-600cfm. Air quality inside the home, especially newer & tighter homes is a huge issue and is oven overlooked leading to excessive condensation on windows, stale unhealthy air we breathe, mold in our walls and a generally more comfortable living space.

Unless:
1. you have a really old leaky house (basically a really inefficient air exchanger)
2. have a fancy carbon recirculating filtration fan above the range, AND and well deigned air exchanger.
3. you never use your stove.

Now that i think of it you could be right. I heat with wood so 5 months out of the year im battling to dry air. The rest to moist air.

 

[RoadBeater]

Not to high jack this thread, but figured for future GJ searches, I'd update it with my results. I installed the EZ Soffit Vent. Retrofitting into my house wasn't too bad. the flapper works well. It's only been a couple of days so far, but I'm pleased with the results. No drafts. I also updated to the Panasonic bathroom fan that is highly recommended on this site, they are much quieter and flow more than the NuTone's that I replaced. Thanks GJ!