View Full Version : Galvanized duct for dryer vent?


quick60
01-28-2012, 09:51 PM
Not really garage related but can galvanized duct be used for a dryer vent?

I have a 12 foot run to cover in my crawl space and did not want to use the flex hose if I did not have to. However the more I think about the moisture issue and even though it is galvanized it may still rust out.

Any thoughts?

Thanks

FrankieD
01-28-2012, 09:57 PM
Have you considered PVC?

quick60
01-28-2012, 10:10 PM
No I have not. That could work I guess. Fire hazard would be my only concern.

DoyleDee
01-28-2012, 10:22 PM
I have seen it used . If it is behind a wall- it is used. It has been a few years since I was installing hvac, but it is what I remember.
I have also seen a telescoping style made out of sheetmetal (rectangular with couplings on the ends).

MN BIANCHI
01-28-2012, 10:25 PM
Galvinized is OK, it will take a long time to rust if ever.

PVC is NOT approved for dryer venting unless it is buried in concrete.

JimVonBaden
01-28-2012, 11:12 PM
Galvinized is OK, it will take a long time to rust if ever.



My new house uses it. Make sure it is insulated so it doesn't sweat into your attic.

Jim :cool:

RHD 4 LIFE
01-28-2012, 11:44 PM
Use 4" white 636 Ipex piping for gas furnace venting!

napaAl
01-29-2012, 12:02 AM
Absolutely. Here in Nor Cal we use galvanized pipe (duct). No screws to catch lint. Tape only at joints. Runs over 13' in length need boosters.

Cougar67
01-29-2012, 01:43 AM
Ha! Like OP I live in VA too! My house was built 15 years ago and I have a 12 foot run in the upstairs crawl space. The laundry room is upstairs. Originally the duct was flexible plastic :shocking: I had the good sense to replace it with the flexible metal. I clean it out about twice a year. I had thought about replacing it with the sheet metal piping they sell for gas water heater venting. The obvious option of venting straight from the back of the dryer would put a hole in my roof on the downward side of a steep slope. I can't imagine what the original designer of this house was thinking. I'm the original owner and although it's a builder home I pored over the plans while it was being built and did catch a few "mistakes." I didn't catch this! What is this "booster" NapaAl speaks of?

rockchucker
01-29-2012, 01:47 AM
Absolutely. Here in Nor Cal we use galvanized pipe (duct). No screws to catch lint. Tape only at joints. Runs over 13' in length need boosters.


100% agreed. ^

Torque1st
01-29-2012, 01:51 AM
I prefer aluminum over galvanized for dryer vents. The galvanized pipe surface roughness seems to catch lint fibers easier than aluminum so clogs build up faster.

Norcal
01-29-2012, 03:36 AM
AL flex duct is not a good choice for dryer venting it will catch lint & build up debris inside. Galvy duct is used around here.

djjsr
01-29-2012, 06:55 AM
I own a laundromat with dozens of large dryers. All have galvanized ductwork and most of it has been there for over 40 years.

If your crawlspace is cold, you may get some condensation. Just pitch the duct so the water can run out.

quick60
01-29-2012, 08:36 AM
Thanks for all of the responses. Guess I will stick with the galvanized.

I could not find aluminum rigid duct. That is what I wanted to use but Lowes only carried the galvanized rigid, the alumunium flex duct, or the plastic wire reinforced stuff that I had no intention of using for this.

THANKS AGAIN!!

steve911
01-29-2012, 08:40 AM
What do you use as a booster for the longer runs?

Torque1st
01-29-2012, 01:58 PM
AL flex duct is not a good choice for dryer venting it will catch lint & build up debris inside. Galvy duct is used around here.

I don't use Aluminum flex duct, I use smooth Aluminum ductwork. It looks just like the standard galvanized stuff just a lot smoother. Aluminum costs a bit more and is harder to find but well worth the effort and cost. The way steel products are going it might even cost less nowadays...

nehog
01-29-2012, 03:00 PM
Have you considered PVC?

Do not use anything that will burn. That leaves out plastics.

sabercatt
01-29-2012, 06:20 PM
install a lint trap as well to help keep it clean

quick60
01-29-2012, 06:39 PM
I found rigid aluminum duct in two foot sections. Pieced it all together and sealed it with aluminum tape. Worked like a champ.

Thanks again for the help.

Torque1st
01-29-2012, 10:17 PM
Cool...

:thumbup:

Where did you find it?

Sorry about the disjointed post. I am having a little diabetes problem, hypoglycemic event.
:(

napaAl
01-29-2012, 10:36 PM
Ha! Like OP I live in VA too! My house was built 15 years ago and I have a 12 foot run in the upstairs crawl space. The laundry room is upstairs. Originally the duct was flexible plastic :shocking: I had the good sense to replace it with the flexible metal. I clean it out about twice a year. I had thought about replacing it with the sheet metal piping they sell for gas water heater venting. The obvious option of venting straight from the back of the dryer would put a hole in my roof on the downward side of a steep slope. I can't imagine what the original designer of this house was thinking. I'm the original owner and although it's a builder home I pored over the plans while it was being built and did catch a few "mistakes." I didn't catch this! What is this "booster" NapaAl speaks of?

They are pressure operated fans. Grainger sells them. The feel airflow from the dryer, and start operating. when dryer turns off fan cools down for a minute or so.

1967marti
01-30-2012, 07:34 AM
I "boster" is just an inline "fan" that will pull/push the air from the dryer. Anything over 13 feet and you will need a booster as at that length and longer the dryer has a very hard time pushing the air.

djjsr
01-30-2012, 08:15 AM
If you install a booster fan, put it someplace where it can easily be removed and cleaned. It WILL get lint build up on it.

WoodiE55
01-30-2012, 08:24 AM
Just curious, why would you not want to use the flex pipe for a dryer exhaust?

dirttracker18
01-30-2012, 09:26 AM
Just curious, why would you not want to use the flex pipe for a dryer exhaust?

The ridges cause lint build up which is a fire hazard.

I am little too late to the party but aluminum is garbage. Too soft and gets damaged too easy. If someone just bumps your dryer you will have a dent in it that allows an escape. Do you use your crawl space for storage? Same issue there, easily damaged. It is hard to find because people are not using it anymore.

With a long run it is a good idea put a lint catch right after your dryer. That way you will not have to clean the run later.

Like this

http://www.lifebreath.com/images/accessories/71.jpg

K'ledgeBldr
01-30-2012, 11:20 AM
Have you considered PVC?

PVC is NOT approved for dryer venting unless it is buried in concrete.

Use 4" white 636 Ipex piping for gas furnace venting!

Runs over 13' in length need boosters.

Anything over 13 feet and you will need a booster as at that length and longer the dryer has a very hard time pushing the air.

Where do you guys come up with this stuff? And 'back-in-the-day' doesn't cut it. IRC (International Residential Code) is for you and everyone's SAFETY. The mere fact that you would mention things that are ILLEGAL boggle the mind. Get the facts! The recommendations outlined below reflect International Residential Code (IRC) SECTION M1502 CLOTHES DRYER EXHAUST guidelines:

M1502.5 Duct construction.Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces, with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.


M1502.6 Duct length.The maximum length of a clothes dryer exhaust duct shall not exceed 25 feet (7,620 mm) from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet (762 mm) for each 45-degree (0.8 rad) bend, and 5 feet (1,524 mm) for each 90-degree (1.6 rad) bend. The maximum length of the exhaust duct does not include the transition duct (the flex duct that is used to connect the dryer to the exhaust duct).


There are clearly no exceptions for duct in a concrete slab. And where most people are ignorant- elbows and bends.

ptschram
01-30-2012, 11:38 AM
Where do you guys come up with this stuff? And 'back-in-the-day' doesn't cut it. IRC (International Residential Code) is for you and everyone's SAFETY. The mere fact that you would mention things that are ILLEGAL boggle the mind. Get the facts! The recommendations outlined below reflect International Residential Code (IRC) SECTION M1502 CLOTHES DRYER EXHAUST guidelines:

M1502.5 Duct construction.Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces, with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.


M1502.6 Duct length.The maximum length of a clothes dryer exhaust duct shall not exceed 25 feet (7,620 mm) from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet (762 mm) for each 45-degree (0.8 rad) bend, and 5 feet (1,524 mm) for each 90-degree (1.6 rad) bend. The maximum length of the exhaust duct does not include the transition duct (the flex duct that is used to connect the dryer to the exhaust duct).


There are clearly no exceptions for duct in a concrete slab. And where most people are ignorant- elbows and bends.

The codes are all fine and good, but in my case, I have a 45 foot run from the dryer to the outlet.

Where the dryer is, there is no route to an exterior wall without an upward flowing vertical run which is also prohibited.

Yet another thing the inspector did not find. As a he's a Neighborhood Code Inspector for a neighboring town, this is disconcerting.

K'ledgeBldr
01-30-2012, 12:10 PM
The codes are all fine and good, but in my case, I have a 45 foot run from the dryer to the outlet.
Obviously, your run is not to code.
...an upward flowing vertical run which is also prohibited.
Another false statement. There is no restriction for direction of duct (other than horizonal runs should have some fall back to the source).
Yet another thing the inspector did not find.
The reason he 'didn't find it' is because there is no restriction- but, did he mention the length was too long(?) There are a few manufacturers that make dryer exhaust vents that specifically made for roof penetrations. Many years ago, I had a particular plan that I built that required this type of setup- all other alternative routes were too long. The only bad part- it was on the front elevation of the house. And after a couple of years you'd start to see lint build-up on the shingles.

ptschram
01-30-2012, 01:56 PM
OK, I can't find where I saw the prohibition on the vertical run.

The duct I removed was flexible plastic that ran the full 45 feet. It has since been replaced with flexible aluminium and will be replaced perhaps next spring with rigid aluminium ducting.

Andrew LB
02-01-2012, 05:00 AM
My dryers duct is long overdue for replacement. The crappy metal flex-duct I currently have has been repaired multiple times because it tears at the slightest touch, plus whoever put it there didn't use their head and installed the full length of it instead of only 2.5 or so feet.

http://www.garagejournal.com/forum/picture.php?albumid=1746&pictureid=16254

For that distance I think the best would be to go with a couple rigid adjustable vent elbows and if needed a short section of straight vent pipe. seal all the joints with mastic and some butyl rubber metallic tape and call it a day.

bd8134
02-01-2012, 11:42 AM
I have installed 2 Fantech inline fans like these. http://www.amazon.com/Fantech-DBF-110-Radon-Duct/dp/B000GXF7KO
They worked excellent and have been in use for over 10 years each.
One is in a vet clinic where the dryer is going continuously and had a long run and they went through many dryers burning out and taking forever to dry.
In the friends house his builder had plumbed his washer and dryer in the basement but not vent to the outside. Even the extractor fan was not vented.. Arrrrrrrrrrrr.
Used rigid galvanised pipe to the side which went to an adjacent furnace room and we used the lint trap that dirttrack18 recommended. Then up to the fan. It has a pressure sensor switch which turns on the vent fan when the dryer is turned on. It then runs for about 10 mins after the dryer switches off.
The dryer installation manual should say the recommended max length of vent pipe that can be used. 90 degree bends decrease this a lot. Anything ribbed will slow down the air flow.

Torque1st
02-01-2012, 02:01 PM
I am little too late to the party but aluminum is garbage. Too soft and gets damaged too easy. If someone just bumps your dryer you will have a dent in it that allows an escape. Do you use your crawl space for storage? Same issue there, easily damaged. It is hard to find because people are not using it anymore.

I have never had a problem with aluminum getting damaged or "dent escapes". It would take some very rough treatment to do any of that.

It is harder to find because Aluminum was more expensive than galvanized and the home box stores push the cheap stuff.

Galvanized 'works' OK, it just clogs faster than Aluminum.

A lint trap is a good idea before a long inaccessible run.

Codes are 'minimum' requirements but they are helpful in that respect.

I try to support my ducts so I don't have to seal and tape joints. It is helpful to be able to take the ductwork apart for cleaning when required.

1967marti
02-01-2012, 02:14 PM
so.......where in the regs does it say not to use a booster fan?

rlitman
02-01-2012, 02:16 PM
My local Ace hardware has aluminum ducting that looks exactly like the galvanized, except smoother. Just like you described. You still have to snap it together the same way.

Oh, and one thing not mentioned. Pay attention to the direction of the duct. You don't want lint catching on the joints either.

shanker
02-01-2012, 02:51 PM
I have also seen a telescoping style made out of sheetmetal (rectangular with couplings on the ends).


Thats the kind I have...I got it because it allows the washer/drier to be MUCH closer to the wall.

ket-tek
02-01-2012, 04:27 PM
I just ran a new vent for a downstairs master suite addition I've been building on my house. Used 4" rigid aluminum duct, one 90 bend. I was 17ft of straight pipe to the 90 and a proper vent flap out the foundation. Joints inserted in the direction of flow, and taped not screwed, suspended every other joist with pipe strap. Inspector checked over the whole run and passed it. He seemed to look it over pretty thoroughly..


In the friends house his builder had plumbed his washer and dryer in the basement but not vent to the outside. Even the extractor fan was not vented..

Yikes, what a bunch of jokers. I can't believe people actually get away with this crap, and worse yet get paid exorbitant amounts of profit to do it.



.

K'ledgeBldr
02-02-2012, 09:52 AM
so.......where in the regs does it say not to use a booster fan?

It doesn't.
IRC codes are "minimum requirements".
Again:
M1502.6 Duct length.The maximum length of a clothes dryer exhaust duct shall not exceed 25 feet (7,620 mm) from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet (762 mm) for each 45-degree (0.8 rad) bend, and 5 feet (1,524 mm) for each 90-degree (1.6 rad) bend. The maximum length of the exhaust duct does not include the transition duct (the flex duct that is used to connect the dryer to the exhaust duct).

Meaning, anything over the 25' aggregate would require some form of booster/assistance.