Hmm, there's something called a "secondary dryer lint trap". It's an inline filter that's designed to be used in front of a dryer booster fan. The question is, can you get away with using it without a booster fan, or will it add too much resistance to the airflow? Your vent run is pretty short, so maybe it would work.

With my current setup, I have the dryer about a foot away from the wall with a rigid metal connector connected from the dryer to the wall that is about a foot long. The dryer is on a pedestal so it goes from the back of the dryer slightly downward to meet the wall. If I get a periscope and connect that since its slightly offset, would this be better? Are periscopes air tight? If I get one, should I use foil tape on each connection or metal clamps or both? I'm thinking that if the periscope were installed the dryer would be RIGHT UP against the wall as opposed to being a foot or so away which would allow stronger air flow through the venting and out the top perhaps preventing lint from building up on the edges of the roof cap and maybe even decreasing dry times. As it is, I can dry a medium load in 40 min's and a large load (jeans) sweat shirts in about 50 or slightly more min's to slightly damp dry. If I want a big load of jeans BONE DRY (which I don't) then I'd say 60 mins but no longer than that.

There's no way to prevent lint accumulation. No dryer has a lint screen of fine-enough mesh to catch it all, and there's always a bit of airflow that gets around the screen.

I had the same setup in my house that you have mark40511. Laundry room in the middle of the house, dryer vented up to the roof. About a year-and-a-half to two years ago I converted that laundry room to a bathroom, and since the garage was already converted when I bought the house, I took a section of the garage room and made a new laundry room. I have always did what u did by crawling up on the roof (steap pitch roof here too, scary as hell). Anyway, when they took apart the laundry room to start the conversion, they took out the venting in the wall. The lint that was in that venting was so thick. I don't know who came up with the idea to vent a dryer to the roof, but they should have their heads checked. Talk about a fire hazzard. Most of my loads were taking and hour plus to dry. Now, my dryer is on an outside wall and vented directly out that wall. My clothes dry in 30, to 40 minutes. Even heavy loads like towels and jeans.

What's the best way to clean "escaped lint" without having to move the dryer?

Well, I just googled and found a great blog regarding this. He used a "LEAF BLOWER!" I have a leaf blower. The other day I was vacuuming behind the dryer and decided to take the clamp off and vacuum out the back of the dryer and in the wall as much as I could. There wasn't very much lint at all in the wall as far up as I could feel. Too bad there's gonna be lint on my roof. Oh well.

A lot of it can be attributed to lazy users too. I have harped on the kids and wife through out the years because I find the lint filter hasnt been cleaned out each use. Sometimes I have found it 1/2 inch thick.

Some fabrics just shed a lot too, like towels. Id hate to live in a household full of pets with pet bedding clogging up the works.

Fordtech, I agree. But I NEVER don't clean the lint filter. I'm the only one to do laundry here. But I do have a question. When installing a periscope for a dryer, since it allows the dryer to be very close to the wall, I'm imagining that there will be barely if any working room since it's 2 inches away from the wall. How do you do this? I mean, I'm sure that once the periscope is fitted on the dryer to the wall, you need to clamp it on and or use foil tape, but with only 2 inches to work with, I'm trying to figure out the easiest way to do it before I even buy one.

I didnt seal it or clamp it. It fits snuggly and the run is so short that the velocity of the air prevents buildup if everything is aligned correctly. That is how it has worked out for me anyway.

I'm installing a new washe dryer. I plan to tape each of the joints and seams with foil to keep the dust inside, no leakage.

When we moved into the house we had the vent (a 10' run up and then 20' horizontal out the side of the house) vacuumed. Two years later we redid the laundry room and I used a leaf blower to blow out the vent. After rigging the blower up to the vent, I turned it on and it snowed lint outside! 10 minutes later lint was still coming out in little clumps. I was amazed at how much was coming out.

Anyway - I recommend cleaning the vent every year with a blow-out :)

Isn't it amazing. Go to youtube and type dryer vent cleaning and look at some of the vids....I'm amazed there aren't more fires than there are!

Mine is about 18 inches of rigid steel. It wont snow there unless we have a blizzard that blows the vent off the house. We get about 2 inches of snow here a year so that probably wont happen..LOL

Well, I bought a periscope dryer vent! What a nightmare to try to install!!!! The part that goes into the wall is "snap fitting" but it was the same diameter of the wall vent. I finally got it in but ended up ruining it. The one I got was very cheaply made. At any rate, while I was back there had I been successful, I don't see how to successfully get a tight secure fit with no working room since it would be so close to the wall. I ended up hooking back up the old setup. There was a waste of 20 dollars. Sigh

Your vent run is pretty short, so maybe it would work.

It isn't short at all.

Unless the dryer manufacturer says otherwise, the maximum straight run is 25 feet. Each 90 degree turn is equal to five feet. Unless I am mistaken, I imagine the OP has a 90 degree piece at the dryer outlet. That plus the 40 degree turn reduces the maximum run to less than twenty feet.

The run is too long.

Are there actually any dryers whose manufacturer doesn't specify a maximum straight run longer than 25 feet?

Fisher & Paykel specifies for their topload dryer models (SmartLoad & AeroSmart):

4" duct, 4" hood
turns rigid duct flexible duct FULLY extended
0 64' 36'
1 54' 31'
2 44' 27'
3 35' 25'
4 27' 23'

4" duct, 2.5" hood
turns rigid duct flexible duct FULLY extended
0 58' 28'
1 48' 23'
2 38' 19'
3 29' 17'
4 21' 15'

I've decided about every six months I'm just going to use my small electric leaf blower to blow my vent out. It's rigid metal all the way through the vertical run (about 18/20 feet) I did it this last time and it worked great. I figured there would be lots of lint stuck to the roof cap exhaust, but there wasn't. Had I gone years without doing this, then probably need a different solution.

The leaf blower technique sounds great. I'd love a fitting that would allow me to do it without moving the dryer and disconnecting/reconnecting its vent.

I just removed my periscope-style duct. Massive improvement on airflow. Those things seem extremely constricting, and I would use them only if it's to connect your dryer to a direct-through-the-wall exhaust.

BTW, if you use a leaf blower, won't the lint collect at the screen on the outlet in the wall/roof?

Heimert wrote: I just removed my periscope-style duct. Massive improvement on airflow.

Very interesting. I have had and used one of these since getting this dryer (several years ago). The dryer has never really worked well, I wonder it the periscope is the cause.

I've not used one, but per pictures of the periscope devices, they don't appear to have much capacity for carrying good airflow and the acute 90° turns at both ends would add restriction.

Richierich53

Honestly, I don't think there is a lint screen or flapper on the roof cap........When this house was built 4.5 yrs ago. I moved in and noticed how fast the clothes were drying as opposed to the apartment I lived in before. As time went on, slower and slower drying times. I thought something was wrong with my dryer. I called for service. The two men got up on the roof and they noticed the builder put a bathroom vent exhaust cap instead of a dryer cap. I called the builder, the guys replaced it with a proper vent cap, though there is no screen/flapper. When I'm in the laundry room, I can actually feel air at the lint screen when I open the dryer door so I know it's clear all the way through, not to mention the fact that lint was all over my roof. I don't know why there isn't a flapper or lint screen. I'm kind of glad there isn't. I dried a huge load of jeans in 45 min's. Some other medium sized loads I can set the timer and depending on fabric they can be dry in 30 to 35 min's. But I have never got a big load of jeans bone dry in 45 min's much less 40. Sometimes I think it depends on the dryer you have as well. Mine is a 4 year old Duet. AT any rate, it's not that hard for me to get behind my dryer to take the leaf blower to it with my setup, so I feel if I do this every six months or so, it won't build up to massive amounts where the leaf blower may not work. I suspect the apartment I lived in prior to this house vented through the roof. I was on the bottom of a three story apartment and the vent pipe went straight up. I don't think they ever clean it and I had no way to. Took me 65/70 min's to dry a load I knew something was wrong.

Most dryers have a periscope vent built into the machine. If you look at the rear of the wall there is a vent usually up high. It has a periscope vent that routes air from the heater air inlet. Then On front of the machine is a large filter with another small periscope vent to the blower housing and then from the blower housing a pipe out to the rear of the dryer where your external vent system is attached. If periscope vents were all that restrictive it would be a problem inside the dryer before you even get connected with your external system. IMHO

fordtech -- the problem is additive. While inside the dryer may have restrictive airflow, the dryer is designed with that in mind. Adding further restriction won't help matters.

We have a similar situation 4 yr old house...dryer vent goes straight up the wall and then angles out the roof. It's about 21 ft. We had all kinds of trouble with it when we moved into the house until we did two things.

First, we had a roofer (DH wasn't about to get up on our steep roof either) come out, and he discovered that the flap and screen on the roof vent were totally plugged. He totally replaced it with a vent that looks kind of like this http://www.homedepot.com/catalog/productImages/400/a3/a37ccece-23e9-4448-b82a-3cc62d5c763f_400.jpg He said it's much less likely to ever get clogged.

The second thing we did was get a Linteater vent cleaning tool and use it. We'd actually initially had Sears come out and "professionally" clean the vent, but they didn't do any good (and probably made it worse) because they wouldn't go on the roof. What they used looked pretty much exactly like the linteater and we actually still got lint out not long after they'd been here. We used it again about a year later and didn't get that much so I think the new roof vent did make a big difference.

GL!

heimert, if you can add 35 feet of rigid pipe with 3 turns, one periscope with 5 or 10 feet of duct isnt going to kill your performance. Maybe if you have some outrageous long exhaust, but then that is the problem to begin with.

Wow. I've never seen a dryer roof cap that looked like that! One other thing I wanted to mention.....the 20 or so foot run of rigid metal that goes straight up the wall into my attic the curves slightly to the roof is not insulated. The attic isn't heated and I have read where this hot air going through the vent will cause condensation to form in the vent causing lint to stick to the inside of the vent. I have also read where some have taken there dryer away from the wall and they had a small pool of water in the entrance of the vent pipe. I've never had this happen on mine.. When I used a leaf blower to blow mine out there wasn't a horrible amount of lint. I honestly don't think it's that bad as long as I do this every six months or so....If I walk outside and look up at the vent cap on the roof, I can see a small amount of lint sticking to the outer edges of the roof cap (even with no screen) But when I use the leaf blower there is barely anything left. If only the roof pitch weren't so steep I could get up there a lot easier

You are right, you must insulate your dryer vent where it runs through the attic. By heating your attic space you will also promote ice damming if it gets cold enough in your area.

I don't know if there is special insulation to retrofit your pipe up there but basically, you want insulation wrapped around, then a moisture barrier over it - I guess you could use wire or cable ties to hold the insulation in place (don't overtighten, you want that insulation to stay fluffy) then wrap with appropriate plastic. I am not sure if the plastic we use as a moisture barrier under drywall etc is suitable or rated correctly for it. If someone here doesn't know what is, you may want to repost your question in the hvac forum regarding insulation.

The most important aspect of why so much lint gets through, which we haven't touched upon, is the necessity to balance safety with blocking nuisance lint (which I guess could become dangerous in itself if you have a fireplace chimney nearby) - if the lint filter was too effective, it would block too quickly and start causing problems like we have been discussing. It would actually make sense for dryers to have some sort of safety bypass like car engines do for oil filters, if too high a pressure in the filter is detected, the filter is bypassed to allow oil to flow freely, rather than starving the engine of oil.

If you have a problem with vermin, it's tempting to put a grate or wire cover over the dryer vent (if it's near the ground) but any covering/straining you do with the dryer vent necessitates more maintenance, as you need to ensure they don't get blocked.

Actually, there are dryers out there, which have very effective filters: heat-pump condenser dryers.

AEG/Electrolux, Bosch/Siemens, Blomberg and Miele have all released heat-pump dryers on the European market. These dryers have multiple filters to protect the heat-exchanger from clogging. Miele's dryer has even got six filters, although they only need occasional cleaning. AEG and Blomberg have four filters. Bosch/Siemens has just one filter because of their selfCleaning condenser, which uses condensed water from the tank to flush the condenser. (watch video)

Alex

Cool idea - I want one. But do they draw their heat from within the house? If so I don't know how efficient they'd be, since they end up extracting heat from your heated space in order to evaporate the water? Or do they pass the air at room temp over cooled coils to condense it? What I do like is how low the energy consumption is, and in winter, any net heat gain goes into your house. This would be brilliant where I used to live (Australia) because for some unknown reason they don't vent their dryers outside. Good in winter heat wise since they also don't heat their homes that much, but bad for humidity/mould, which they have plenty of. The literature didn't explain how they work exactly, but interesting idea. When I had a dehumidifier in Oz, I often dried clothes in front of it.

Heat-pump dryers work like a fridge: the inside of a refigerator is cooled by extracting heat from the inside of the unit and emitting it via the black coils on the back. A heat-pump dryer uses this heat to dry the laundry and the cool air to condense moisture from the drying cycle. Regular drying temp is 130°F

Here is a link that might be useful: Miele heat-pump dryers slash operating costs

I was surprised how much lint there was on the ground near our vent. Normal or a sign that cleaning is needed?

HOw can I tell if my dryer is catching enough lint?

I have a 1-yr old LG steam washer/dryer stacking combo. They work great, but the dryer started taking much longer recently. Called LG service & they diagnosed the problem as a venting issue. Contractor came out & cleaned vent (goes through ceiling with ~6' run to ceiling & roof vent with flap & small screen). Problem was that external screen (~3" x 6") was clogged with lint, which caused a huge backup in the vent pipe.

Now dryer is working fine again; however, I have to go up on roof & clean small external screen very often (every 3-5 dryer cycles). Is this normal? It seems excessive or this the price to have a roof vent with a screen to discourage vermin/birds from entering vent?

Would appreciate any insight that people can offer.

Thanks

Hello. My dryer roof cap had a screen on it and I took it OFF! If you don't it will always clog up.

Had my new washer delivered on Saturday. When they removed the old one I was cleaning the floor and walls before they put the new one in, when I noticed tons of lint behind the dryer. The delivery guys from Loew's moved out the dryer for me and we discovered much more lint underneath (like a blanket) the dryer. The rigid duct was not connected anymore and had never been clamped to begin with. Our dryer vents directly outside and only has 8-10 inches to the wall. He put on the aluminium foil laminate transition duct instead. Is this OK? I thought some escaped lint was normal, but now I will be more aware of what I can see behind the dryer, outside where it vents and how much lint I am collecting in the filter. I think over time I didn't notice as much in the dryer filter, but wasn't aware of the accuulation. I know my duct is short compared to some but what about this type? Thanks

You get most of the lint problems and buildup if you do not change your lint each and every time.

I've never heard of a leaf blower to clean a dryer.

There are also several attachments you can use with your vacuum -- depending on the type of dryer you have. Check Sears or Home Depot. If you are really creative you can go to Home Depot and get a plastic hose and try and fit it on your vacuum and stick it in there.

I'd do this as there have been reports of fires if not cleaning your lint. The rule of thumb is if you start to notice that your clothes are taking longer to dry; you may have a lint problem.

Here is a link that might be useful: lint reviews

Lint screens are only designed to catch 60% of the lint. If it was designed to catch 100% then you would have no air flow for the moisture to escape. I have been cleaning dryer vents since 2008. All dryer manufactures suggest that dryer vent lines be cleaned once a year. We have seen several times where the roofer put the wrong vent on and it caused lots of problems. A properly installed and maintained dryer vent will allow the dryer to breath and clothes to dry in a reasonably time whether it is a roof vent or a wall vent.