Here’s the crazy question of the week.  I am just completing installing vinyl siding on the house and we totally wrapped the house in tyvek as a moisture barrier,  our house has always been very tight but I noticed yesterday that when the HVAC runs, the dryer vent cracks open a bit and cold air was blowing out.  I’m considering attaching a small weight (maybe an ounce) to keep it close see especially for the heating season.  I’m really surprised at this phenomenon because the dryer is a high end LG and I figured it would be tighter than it is.  Anyone run into this issue?

I think the vents for the dryer staying easy to open is more important than the amount of air you are loosing through those vents with the air and heat..You sure don't want lent to get trapped and build up....

 It also sounds like you have holes in your heating air ducts..and thats not good..

Edited September 20, 20187 yr by Smallpatch

I can't say that I've ever noticed it. But I don't think the light weight is a good idea, the dryer really needs free flow when it's running.

20 minutes ago, Smallpatch said:

 

 It also sounds like you have holes in your heating air ducts..and thats not good..

 

The house is built on a slab and the ducts are in concrete so I don’t think that is possible.  Not impossible, I guess. 

Is the dryer located in a closed room with a hvac duct that could pressurize the room ?   As far as the dryer, it sucks in room air that is expelled to the outside, I wouldn't expect it to be tight.  Roly

Roly, the dryer is is a utility room off the kitchen and is wide open.  For clarity sake, the vent only cracks open about 1/2 an inch.  It’s wild because you can open the back door and neutralize the  pressure and the vent will close.  The furnace is a new 97.5% efficient unit with a variable speed motor.  Much more potent than the older one.

Ron  a slab would be different for my house is a double wide and duct work is completely different than yours.

  If enough air is coming through the vent all the time it might be a problem for insects getting in the house. If the dryer is running, hot air is escaping and the insects would not be a problem then.

Wouldn't do it Ron for reasons already mentioned.

Are you sure this condition didn't exist prior or at least since you installed the new HVAC unit earlier this year?

Roly may be on to something...if the dryer is in a utility room or utility closet, try leaving doors to the area open( didn't see your response while I was submitting this)

Edited September 20, 20187 yr by Grandpadave52

1 minute ago, Grandpadave52 said:

Wouldn't do it Ron for reasons already mentioned.

Are you sure this condition didn't exist prior or at least since you installed the new HVAC unit earlier this year?

Roly may be on to something...if the dryer is in a utility room or utility closet, try leaving doors to the area open

Dave, the dryer vent is brand new and swings free.  That’s probably part of the issue.  Roly has a good point that I had forgotten.  The dryer has to be porous or it won’t dry clothes. Duh.

Is your dryer duct work also in the slab or does it exit through the wall? If through the wall, all seams & connection points secure & tight/taped?

Is there an air vent close to the dryer? If so, might try some sort of deflector to redirect the air flow.

2 hours ago, Fred W. Hargis Jr said:

I don't think the light weight is a good idea,

2ND THAT MOTION!!!!

Unless you have a window open somewhere drawing air into the house then there should not be any reason extra air is trying to exit. 

I know people who use natural gas should have some outside air coming in and that might be what you are watching go out the vent. Otherwise I wouldn't worry ..

You don't want your house 100% tight. Most forced air systems draw a portion of their air from the outside, besides the combustion air for the gas fired units. They don't just circulate the same air as is in the house. When the furnace /AC turns on it is pressurizing your house.

I don't think that the dryer vent opening is a problem unless it doesn't close when the system shuts off.

Herb

giving it some thought...

how is the air getting into the duct to start w/... you should be looking for a leak in the ducting or bad gaskets on the dryer...

and Herb is correct... you do not want a sealed house..

sealed houses are sick houses...

If the dryer door is shut and sealed, how does conditioned air get in the vent hose?

50 minutes ago, Gene Howe said:

If the dryer door is shut and sealed, how does conditioned air get in the vent hose?

Apparently, it doesn’t seal.  Besides, it has to breathe because it is exhausting air.  

59 minutes ago, Gene Howe said:

If the dryer door is shut and sealed, how does conditioned air get in the vent hose?

When the furnace/AC starts up it is pressurizing the house . The air gets into the dryer through the back where it draws it's air to dry the clothes.

Herb

 

 

 

Herb. I'm not following that. The HE furnaces usually have a semi sealed combustion chamber that draws air in from the outside for combustion, and then it exits as the exhaust. The circulated air in the house should be just that, circulated....not exchanged with the outside (unless he has a fresh air intake). What did I get wrong?

your house '' leaks '' at the doors and windows a little... at least we hope so...

the furnace kicks on and pulls air into the house from those '' leaks ''..

the house is then pressurized....

the pressurized air then goes into the air intake on the dryer and out the vent...

you do not want a sealed up house...

 

But...but...but...air is pulled into the dryer by a fan which only runs when the dryer is operating. 

I don't understand how conditioned air builds enough pressure in a house to open the dryer vent. If it does somehow, I'd be worried about all the pilot lights and possible CO build up.  Sumpin' ain't kosher.