Dryer venting question

[thammel]

I know this is not the perfect place to be posting this question but at least it's insulation relevant. I've got a new attached garage, attached via a new mudroom/laundry room. I'm doing the laundry room finishing and one item is the dryer vent. I've got 2 x 6 exterior walls and the dryer will be up against an exterior wall. I am simply planning a straight shot vent with an exterior flapper and an extra flapper toward the interior wall. The wall will be insulated, or course, but there will be some extra heat loss at this dryer vent. Does this all sound ok? I've been reading about a "dryer box" on line that enables downward or upward venting (I think this is when you're not against an outside wall) - but I don't see how this would help in my case. I'm just wondering if there's any way to improve (reduce) the heat loss situation.

Thanks for any comments!
Tom

 

[tfi racing]

The only advice I can give is place it high enough so that critters can't easily crawl inside!

 

[rsanter]

I think you are doing it right
I added the second flapper on the inside and I think it works great. yes you will have some loss of insulation Rvalue but it will be no big in the greater scheme of things

bob

 

[nate379]

At my old place when I first moved in there was no flapper. In the winter there would darn near be icicles in the dryer!

I fixed that along with a few other things... maybe $200 worth of sealing/insulating and I cut my heat bills almost in 1/2!

 

[cortez]

I know this is not the perfect place to be posting this question but at least it's insulation relevant. I've got a new attached garage, attached via a new mudroom/laundry room. I'm doing the laundry room finishing and one item is the dryer vent. I've got 2 x 6 exterior walls and the dryer will be up against an exterior wall. I am simply planning a straight shot vent with an exterior flapper and an extra flapper toward the interior wall. The wall will be insulated, or course, but there will be some extra heat loss at this dryer vent. Does this all sound ok? I've been reading about a "dryer box" on line that enables downward or upward venting (I think this is when you're not against an outside wall) - but I don't see how this would help in my case. I'm just wondering if there's any way to improve (reduce) the heat loss situation.

Thanks for any comments!
Tom

Many (if not most) people I know who are cost conscious use a cheap and readily available gizmo that filters out the lint but lets the heat from the dryer to enter and remain in the room (both electric and gas).

This is ok if you are not allergic to gas fumes (carbon monoxide) from the gas type dryers.

The second problem is the build up of mildew that will form from the un-exhausted moisture everywhere and require regular cleaning/killing of the mildew.

If someone in your household is allergic to mildew the doctor bills to figure out what the hell is the cause of a host of ailments will easily drown out any savings from this lint catcher.

I found out the hard way that mildew can cause medical mysteries that require CT scans, MRI scans, 600 dollar blood tests, multiple skin tests, visits to the ophthalmologist, neurologist ect.,ect.,ect..

In my garage I am the King and I "open vent" the hot water heater as my sole source of heat (and hot water).

Now, if you have a garage and living space that can "communicate" contaminants this is an entirely different situation if you do not live alone.

 

[redsky49]

If you choose to install a second back draft damper, please ensure that it will operate properly. (Typically these are not recommended by the manufacturers. Added resistance to air flow (which is what a gravity damper causes) slows the exhaust airflow velocity, allowing more of the lint and dust in the airstream to settle in the duct and on the damper. This in turn reduces the performance of the system, allowing even more lint to settle in the duct in a continuing process).

Provide the dryer vent size as recommended by the dryer manufacturer.

Reduce the number and severity of all elbows in the vent flexible duct.

A smooth inner duct surface operates far more efficiently than a corrugated one.

Clean accumulated dust from the accessible areas of the system, particularly the damper surfaces. Use and maintain the dryer vent filter.

Oftentimes, simply keeping the dryer door fully closed will help minimize infiltration. In such cases, the only heat loss is the portion of the exhaust duct within the conditioned space, and this is typically a very minimal amount.

The reason for my concern is that the buildup of lint in the exhaust can result in damage to the dryer, as well as being a potential for fire. In large commercial laundries, lint and dust can be an explosive combination. In large apartment buildings it is frequently a maintenance nightmare. Not to be an alarmist, just be sure to maintain the system.

As always, offered only as opinion

 

[rocketman]

I live in the Chicago suburbs and the vent to my dryer is a short straight shot outside. (developer/builder design) It has a single outside flapper. It is about 18" off the ground and nothing has ever crawled inside nor do I notice any heat or AC loss in the very tiny room. It is a mud/laundry room between my attached garage and family room. Snow has been to the top of the vent and the heat from the dryer just melts a path to the surface. No problems in 14 years. I'd think I prefer the shortest, straightest shot outside to prevent lint buildup in the hose. The fire hazard created by the lint is far greater than any heat loss you'd need to be concerned with.

 

[thammel]

Hey Rocketman,

Sounds good - that's the exact arrangement I have except that it's more like 36" off the ground. My thought is that the straight shot is by far the best for minimizing lint and all other losses.

Thanks!
Tom

 

[ddrewyor]

The outlet my builder used has 4 or 5 flaps that layer on top of each other. I have not experienced any issue with wind coming into the dryer in the winter and making it colder in the laundry room. We live is a mildly rural area and there are lots of critters and nothing has ever climbed inside for a warm nap It's about 10" off the ground and works great. For cleaning out the lint, I just "bow" the plastic louvers, they pop out, I vacuum, and then put them back. Use smooth wall pipe as it doesn't collect lint. Never use the white or aluminized "slinky" plastic tubing. If a short run of flex is required, use the all aluminum flex. Take care

Dave
________
Buy Iolite Vaporizer

 

[Scotto]

If you choose to install a second back draft damper, please ensure that it will operate properly. (Typically these are not recommended by the manufacturers. Added resistance to air flow (which is what a gravity damper causes) slows the exhaust airflow velocity, allowing more of the lint and dust in the airstream to settle in the duct and on the damper. This in turn reduces the performance of the system, allowing even more lint to settle in the duct in a continuing process).

I was going to bring up the same thing. I just have a flapper on the outside of the house and check it every once in awhile to make sure it isn't clogged with lint. That would be a little hard to IMO with another flapper inline.