Dryer vent cleaning, routing

Telco · May 2008

My house was built stupid. The laundry room was built in the middle of the house, with the vent coming out on the roof. This means there is about a 40 foot run from the dryer to the outside, with two 45 degree angles and at least two 90 degree angles in the run. On top of this, there was a vent cap on top of the roof to keep rain out, that resulted in the vent having four holes to let the air out that were about 3 square inches each. As you can guess, it didn't take long to clog the whole line. And, as my roof has a 12/12 pitch (damned steep) and the outlet is kinda high on the roof, it doesn't lend itself to easy cleaning.

Anyhoo, when we moved in everything was fine, but as time wore on it took longer and longer to dry clothes. Up till last weekend it was taking 2-3 dryer cycles per load to get the clothes dry. This weekend I finally braved the roof (I hate heights) with the aid of a rope and my pickup truck, which acted as an anchor on the far side for the rope. I replaced the little vent outlet with a huge gas heater vent, with the anti-bird's-nest netting cut out, and cleaned the line out as well as I could. Net result: clothes that used to take three 80 minute runs now take one 80 minute run. I'm hoping to see enough savings to keep my power bill close to 100 a month this summer instead of the normal 150 a month with the AC on.

Anyway, the reason I posted this up is as a warning, keep your dryer vent cleaned out. And, if building a house, INSIST on having the laundry room on an OUTSIDE wall, and insist on having the dryer vent go right through the wall.

n3qik · May 2008

Re: Dryer vent cleaning, routing

I here you on this. A co-worker is having a big fight with the condo association over the same set up you have.

When I brought my used gas dryer, first thing I did was rip it down a clean out ALL the lint. You will be surprise how much was inside it next to the heater.

icarus · May 2008

Re: Dryer vent cleaning, routing

You can buy a dryer vent brush with a flexible handle that you can push up from the bottom, and not have to go onto the roof (assuming your rain cap is clear) It will go around the elbows with a bit of effort. The problem with it is the rain caps. There are a number of rain caps for 4' vent pipe that won't clog. Another trick is to send the brush in, with an airhose attached so that you can blow the lint out the top with the air. When I have cleaned them from the top, (I used to service a couple of commercial accounts) I leave the driers blowing to blow the lint out.

Icarus

Telco · May 2008

Re: Dryer vent cleaning, routing

Where do you get the brushes from? The local big box home stores don't have them.

icarus · May 2008

Re: Dryer vent cleaning, routing

Don't have a name brand off the top of my head. If you can't find one locally, try the worlds best (I kid you not!) hardware store "Hardware Sales" in Bellingham, WA (www.hardwaresales.net) They are not really a e-store, but you can call them with a cc and they will send something out to you.

The brushes I have used look like a chimney brush, with a wound wire handle like a plumbers snake. If memory serves it comes with ~20' of handle. I can't remember if you can couple a few of them together. The handles are able to go around a number of elbows without trouble. The biggest problem is if people have put the duct together with screws that protrude into the duct. (A UBC code violation by the way)

Good luck.

Icarus

PS Hardware Sales is really the worlds best hardware store. They have everything even the most obscure item that you can think of, they know where it is, what it is for. The people know what they are doing and if they for some reason don't have it they will get it quickly. No offence to this site sponser (who also provide great selection at fair prices) most of the hardware they sell I can get off the shelf AND a lot more. Sometimes it is nice to see stuff in hand. A left handed metric fine thread stud 12mm? They got it!

Telco · May 2008

Re: Dryer vent cleaning, routing

Excellent, thanks! Saving that link.

Incidentally, my dryer line is taped at every visible seam, EXCEPT where the stupid undersized cap was installed. The new cap is a pressure fit with a side clip, almost as secure with no screw heads to grab lint.

What was on there:

What's on there now, modified. A lot of the smallest metal legs are missing so that the cap is supported only by the main legs, for better lint flowthrough:

What I would have used had I seen it:

icarus · May 2008

Re: Dryer vent cleaning, routing

Telco,

All your caps are lint traps. They make a simple "China Cap" to fit a 4" line that just covers the top of the pipe, without covering the sides. Your second picture is a "B" vent cap for gas venting, full of lint traps. The final picture looks like a back draft dampered bath fan or range vent cover. Depending on the configuration of the damper it might work ok. Your first picture looks like another "B" vent cap I have seen. If you are having trouble finding stuff at your local "box store" try the local HVAC wholesaler, ie Gensco or Ferguson. They stock a huge variety of caps and stuff. (They may not sell to you, but if you find what you want, you can find a contractor to order you one).

The simplest solution, aside from the "China Cap" is to put a double elbow on the termination of the pipe, so that it points down. No water can enter but it makes it hard to clean. In the real world, having no cap at all is not a huge crime in most areas, as any water that gets in, is dried quickly when you run the drier.

Icarus

Telco · May 2008

Re: Dryer vent cleaning, routing

Cool, but I'm not climbing back on that roof until I have to. The slope is so steep I had to throw a rope over the house and tie it to my truck, risking having the cops called on me for parking the truck in the grass. That crappy cap lasted about 4 years before there was a real problem, the one I have now is much larger (also had to put a 4 inch to 6 inch adapter on) and a lot of the grids have been cut out. This one may not ever clog up.

I also don't think it's a good idea to leave it open. The hole is a 4 inch diameter hole, which means that with a storm that drops 4 inches of rain I could potentially have a half gallon of water dropped down the back of the dryer. Half a gallon of water will cover a 1 square foot surface with 1 inch of water, and four 4 inch diameter pipes will cover almost an entire 1 foot square area. And, our last big storm dropped 8-9 inches of water overnight.

I may go with the 180 degree elbow if this one clogs and I have to go back up again.

BB. · May 2008

Re: Dryer vent cleaning, routing

Actually, a 4" dia. pipe in 8" of rain will take in about a quart of water because a 4" pipe is only 6.3 sq.in. whereas a sq.ft. is 144 sq.in. (4" pipe is ~4.4% of a square foot).

Per Crezwer--who has corrected me... 4" pipe is 12.6 sq.in.... So 8.8% of a sq.ft. and .47 gallons of water in 8" of rain... ......tbhz -Bill

Still not great--but not as bad as you thought.

I too am a big believer in mounting the drier as close as you can to an outside wall... You might also try insulating the vent runs (if you have access)... I always had troubles with lint collecting at the end of longer runs (even with 6' of plastic pipe)--and it seemed soggy. When I installed drier at my new home (2' run), there is no collection of lint at all--My theory is because the pipe walls don't get damp and glue the lint down as the pipe walls stay hot.

Probably nothing you can do to change your long runs and many turns when the drier is in the middle of the home.

Only reason I am on the math is I am trying to teach my children this stuff right now (and to be more careful with their math too).

-Bill

niel · May 2008

thanks for mentioning about condensation bill. my dryer vents to the outside wall in my basement and i thought my flex pipe was just accumulating the lint from being caught in the ribs in the pipe, but my cold basement would cause the moisture produced in drying to be condensed on the walls of the pipe and accumulating the moisture causes that lint to stick more readily than the ribs would. note that i simply wash out the lint with my garden hose occasionally after easily removing the pipe and wouldn't be easy to insulate it or worth it for me.
if innaccessible or if the pipe is to be permanent, the insulation may stop the moisture accumulating on the pipe and thusly the lint from accumulating. telco, this could be the case with your vents as the outer portion is exposed to the cold air and moisture is sticking to the interior of the vent even though flowing to the open air. with no insulation the temperature differential is still big there on the vent even when the dryer has been running for awhile and is most pronounced at the roof. i will say that all dryer vents initially would be cold due to ambient air temps making it cold and condense the moisture. as it warms through the dryer use, the insulated vent would simply stay warm as it is insulated and evaporate the moisture it initially condensed. an uninsulated vent continues to have a cold outer edge and may not cause the evaporation of the condensed moisture through the continued use of the dryer. does this make sense or did i confuse you?

icarus · May 2008

Re: Dryer vent cleaning, routing

The enemy is distance and obstruction in the vent. (as well as the number of elbows!) Most codes require a backdraft damper which causes it's own set of problems. The lint gets caught in the damper, causing it to neither open nor close properly. If you use your drier often the losses are minimul with no damper. If you use it rarely, consider a manual plug that you remove when you need to use the drier.

Better yet, hand your laundry out.

Icarus

Telco · May 2008

Re: Dryer vent cleaning, routing

BB. wrote: »

Actually, a 4" dia. pipe in 8" of rain will take in about a quart of water because a 4" pipe is only 6.3 sq.in. whereas a sq.ft. is 144 sq.in. (4" pipe is ~4.4% of a square foot).

Still not great--but not as bad as you thought.

I too am a big believer in mounting the drier as close as you can to an outside wall... You might also try insulating the vent runs (if you have access)... I always had troubles with lint collecting at the end of longer runs (even with 6' of plastic pipe)--and it seemed soggy. When I installed drier at my new home (2' run), there is no collection of lint at all--My theory is because the pipe walls don't get damp and glue the lint down as the pipe walls stay hot.

Probably nothing you can do to change your long runs and many turns when the drier is in the middle of the home.

Only reason I am on the math is I am trying to teach my children this stuff right now (and to be more careful with their math too).

-Bill

I know where I went wrong on the math, was thinking 4 pipes would take up the square foot when it is 9 four inch pipes. Would be 4 six inchers that take up a square foot. That was plain 'ol not paying attention on my part.

I'll consider insulating it, there's about a 15 to 20 foot long section in the attic where insulation could be wrapped around it, up to the roof.

My last house also had this stupid routing, but it was done with a 3 inch corrugated hose that dumped directly into the attic. Luckily on that one the laundry room was on an outside wall, so I chiseled a 4 inch hole through the rock exterior and installed a 4 inch dryer vent that dumped straight outside. No more problems for that house.

crewzer · May 2008

Re: Dryer vent cleaning, routing

4" pipe is only 6.3 sq.in.

Jim / crewzer

BB. · May 2008

Re: Dryer vent cleaning, routing

crewzer wrote: »

Jim / crewzer

Ugh... 12.6 sq.in....

Earlier post updated with correction...

-Bill

blwncrewchief · May 2008

Re: Dryer vent cleaning, routing

Being in the HVAC business, dryer vents have become a very common problem. When you figure dryer manufactures only allow 15-25' equivalent run pretty much if it doesn't vent straight out the wall your in trouble. Don't forget to figure every elbow as 5'! If your dryer vent is more than 15-25' equivalent you are wasting a ton of energy. If you have a long run you might want to consider a dryer vent booster from someone such as Fantech. http://www.fantech.net/fantech_laundry.pdf I have installed a few for customers and they have made a drastic difference. the last one I installed had a 50' equivalent run and she claimed it cut her drying time in less than half. Just some food for thought.

Telco · May 2008

Re: Dryer vent cleaning, routing

Got one, thanks. Helped a lot even with the clogging exhaust vent.

System2 · July 2008

Re: Dryer vent cleaning, routing

blwncrewchief wrote: »

Being in the HVAC business, dryer vents have become a very common problem. When you figure dryer manufactures only allow 15-25' equivalent run pretty much if it doesn't vent straight out the wall your in trouble. Don't forget to figure every elbow as 5'! If your dryer vent is more than 15-25' equivalent you are wasting a ton of energy. If you have a long run you might want to consider a dryer vent booster from someone such as Fantech. http://www.fantech.net/fantech_laundry.pdf I have installed a few for customers and they have made a drastic difference. the last one I installed had a 50' equivalent run and she claimed it cut her drying time in less than half. Just some food for thought.

FYI in our house we have a dryer run in our slab that's 30 feet long with 2 PVC 90's (didn't use sweeps or street 90's) and it isn't graded right so it pools just enough water in the middle to collect tons of lint :grr

I have a room right above the laundry so a roof run is not optional either. I ended up running some regular 14 gauge underground wire (fused at 3 AMPS too in case it wears through) that I run in the dryer duct and I have one of the fantech fans in the exterior housings. It literally cut dryer time in half and it also pulls enough volume to keep that water from pooling. Had it about 6 months and have had no issues with it. I highly recommend it!

JT

Telco · July 2008

Re: Dryer vent cleaning, routing

Update: We had a super strong wind 3 days after I installed that new cap. Blew it clean away. When I found it, it was too damaged to re-use. I am now sporting two 90 degree turns right on the end to dump to the roof. Should not ever be a problem again, as if any restriction builds up the blower fan will activate. Seems like there's not enough restriction in the line anymore to need the blower fan as it no longer comes on, but it tests fine.

I may pull it off and store it for another time, or maybe ebay it.

Brock · July 2008

Re: Dryer vent cleaning, routing

How big is the pipe? I have no idea but what about birds or creatures climbing in the pipe? Right now they wouldn't make it past the fan right?

I am not sure if it is the way to go, but in our new house they ran the 4 inch dryer line down to the basement (18 inches) then 90* it and expanded it to 6 inch, then ran that about 15 feet and another 90* and then outside, still at 6 inch. At that location I have a 6 inch dryer vent, 6 inch HRV exhaust vent and 6 inch from the stove exhaust hood. I know going to a larger size should help reduce backpressure and prevent clogging, could that be a problem in any way?

System2 · July 2008

Re: Dryer vent cleaning, routing

The cops come when you park your truck on the grass?

Telco · July 2008

Re: Dryer vent cleaning, routing

Brock - 4 inch diameter with a 4 to 6 adapter, then the two 90s are 6 inch. Nothing in place to keep critters out, but they wouldn't be able to get past the fan. I do need to put a screen across it though, hate to find a mummified bird on top of the fan one day.

Sage - Yep, it's illegal to park on the grass in the town I live in. Stupid law plus busybody old biddy equals a pissed off cop having to do grass duty. The cop that came out to speak to me about it said there was one lady that keeps calling them about stupid stuff like this, and he had several other houses to speak to. Either she lives in the back of the neighborhood or likes to go all around checking to see who's doing what. No idea who it is or she'd be convinced to either move out or mind her own business. Yet another reason I can't wait to sell my McMansion and get a few acres in the sticks, it really bugs me that my neighbors have control over my property. As long as I'm not messing with their business they shouldn't be messing with mine.

icarus · July 2008

Re: Dryer vent cleaning, routing

Sage,

I would at least consider the wisdom of increasing the diameter of the pipe, if you are not going to add an aux fan. My intuition would be that while the back pressure would be reduced, the velocity of the air might slow down enough to let lint settle. Sharper HVAC minds than mine might have a more considered opinion.

Tony

Dryer vent cleaning, routing

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