You could buy a ventless dryer.

The problem with the booster fan is what could happen if it failed and you didn't realize it, which is within the realm of possibility. If it did, you would likely have a significant lint build up and possibly a fire hazard.

You cannot vent into a garage, nor do you want to.

What kind of foundation do you have? If you have a crawl space or basement, sometimes you can use that to reach the outdoors. However, each 90 degree turn is counted as five foot of vent pipe. The total allowed is generally 25 feet or the dryer manufacturer's recommendation, if it differs. Unless your driver vents straight down, you use up ten foot of your 25 foot allowance just getting into the crawl space or basement and aimed in the right direction.

You might call your local building inspector and ask what criteria is used in your jurisdiction.

I had no idea that there were ventless driers! Not much of an option though because of the selection, but cool nonetheless.

creek_side,

I am worried about the booster fan failing for sure. Unfortunately, the foundation is a post-tensioned slab so no real way to vent the dryer except out the attic or into the garage.

I'd love to talk with an inspector about a number of things but I have not been able to contact one! I've called the number listed for the city of Houston building inspector but all I get is some assistant who doesn't know jack. I asked him about installing a window above an electric range and his answer was "your builder can submit the plans and we'll let you know if it's within code". Really? How about just letting me know if it's against code or not?

phillipeh,

Sounds like your contractor was awesome ;) The interesting thing is that the code says that a dryer can be unvented if it is in an open area, but if it's in a confined area (closet, etc), it has to be vented to the outside.

This is something I really didn't even think about when working with the builder.

If you post your floor plan, perhaps we could suggest a way to run the vent in a small chase, if it's not too late to construct one.

Dryer booster fans are not a problem for runs up to 100 ft. as long as they are designed and installed properly.

If the booster fan fails, the result would be the same as if the main dryer fan failed or the duct got filled with lint and: your clothes take forever to dry, so you would be aware of it before there was any danger.

I would try to avoid putting the ducts in inaccessible locations.

Here is a link that might be useful: booster fans

Can you post your floor plan? Maybe you could run the vent through the garage, but vent it to the outside (don't dump the air into the garage). I would never vent a dryer into the garage.

Ducts that penetrate walls or ceiling separating the house from a garage are not allowed to terminate or have openings into the garage. Ducts that pass through the garage must be 26 gage steel.

Sorry for my tardy replies, I just got home and got done getting dinner fed to the kids.

We are building a slightly modified version of this floorplan which includes the downstairs theater:

http://www.triumphhomes.net/plan.aspx?PlanId=4402

I hadn't thought of running around the garage, that might work. As it sits now, I believe that it is vented straight up and out the roof. I hadn't thought about this before, but I *could* go up the laundry wall, then turn and go through the joists above the theater and out the side wall there. That would be ~25' with three 90degree elbows vs ~30' with one 90 degree elbow.

Here is a link that might be useful: katie floor plan with downstairs theater

The equivalent duct length of a 90 degree elbow is 5 ft so the original design would be 40 ft and the alternate would be 40 ft

Booster fans for dryers vents are prohibited under all Building, Mechanical, and Electrical Codes EVERYWHERE in the US.

There are absolutely NO DRYER BOOSTER FANS that are LISTED or APPROVED by 3rd party electrical, mechanical, or building testing laboratories anywhere in the US or Canada.

I challenge ANYONE who claims otherwise to cite the source of their information.

In the United States, there are currently NO booster fans approved for installation in any commercial or residential dwelling.

None.

This may help.

Here is a link that might be useful: Dryer Ell

"Dryer Ells" only help if the total run is less than the 25' maximum allowed by most building and mechanical codes.

The question remains:

DO or CAN 'dryer boosters' be installed in US applications?

The answer remains absolutely NO under every and any circumstance!

He may be able to go up the laundry wall and across the garage/home theater ceiling to an exterior wall penetration. The ells just may keep him at the 25' maximum.

They have nothing to do with any dryer booster.

If anyone is curious to know why dryer booster fans are marketed and installed in every state in the US, I will briefly explain it but I don't want to get into a pointless academic nit picking argument about national building codes. If you don't understand or you disagree with what I say, please find a professional code consultant or join the ICC and ask for a written clarification rather than quote chat room comments by others equally confused about the subject. I don't really care who uses these fans or what others think building inspectors believe is allowed because they are allowed in every state where I practice, but no one should be led to believe they cannot be used anywhere in the US or Canada.

Up until the 90's Underwriters Labratories (UL) tested and listed dryer booster fans using their own published testing standards. Until UL decides to test these devices again it is not possible for a manufacturer to offer a UL listed dryer booster fan device. This does not mean that the devices are unworthy of testing or can no longer pass the UL tests. Fan manufacturers are currently lobbying on and with the UL committee to get UL to resume testing.

Not all of the states and local jurisdictions in the US have adopted the 2006 or 2009 IRC; many still use the earlier codes that allow booster fans. Some use the later codes but have amended them to put the earlier provisions for booster fans back in. Many jurisdictions allow the booster fans as an "alternative design/method" under Section 104.11 which says:
"The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is for the purpose intended, at least the equivalent of that prescribed in this code."
[The use of the command form "shall" should be understood to be a strong indication that the ICC does not wish to limit the design of building to only what is stated in the code text. Many jurisdiction require the building official to accept a compliance alternative proposal from a "qualified" state licensed architect or engineer and the building officials I have dealt with have always required a stamp in order to avoid liability for such alternatives. No one wants building officials to design buildings, least of all the officials and the municipalities they work for.]

In terms of safety testing certification, fortunately CSA International tests dryer booster fans using UL's published test standards. Many people unfamiliar with safety testing or haven't been keeping up with it, think CSA Int. is only recognized in Canada and is not the equal of UL, but it is accredited by OSHA as a Nationally Recognized Testing Laboratory (NRTL) and recognized by ANSI. CSA Int. conducts tests using the same American industry standards as other accredited testing laboratories, regardless of who authored or published the standard. CSA Int.'s listings and product marks are recognized and accepted throughout the US by federal, state and local authorities.

An example of fans tested and approved for use in a dryer booster system by CSA Int. is their certification of FanTech's dryer booster fans titled: "FANS AND BLOWERS - Certified to US Standards"
That document says: " THE FOLLOWING MEET THE REQUIREMENTS OF UL STANDARDS 507 AND 705:
- Residential/commercial ceiling mounted ducted clothes dryer exhaust booster Models CVS-275A-SI rated; 115V, 60Hz, 0.75A (suitable for 60C max inlet air temperature) ...."
[There follows a list of fans but in order to use them it is necessary to provide a building inspectior with the corresponding FanTech model numbers which are available in chart form from FanTech.]

If you want to use a FanTech fan and the local building official is not sure if it is allowed, call FanTech and ask for assistance. Their fans continue to be installed in all 50 states and they send out appropriate documentation for building officials every day.

The only cautions I would add is to be very careful about venting a gas fired dryer (with or without a booster fan) and don't install the booster fan in the first 15 feet of the dryer duct. FanTech makes a model (DBF4XLT) that has an indicator panel that mounts near the dryer and shows if the fan is operating properly. With or without a fan or an indicator, if the dryer starts taking too long to dry clothes, have it serviced immediately or at least inspect the duct.

Any death by fire is unacceptable and precautions should be taken to minimize the danger from all potential causes of fire, however, it is not true that dryer or other appliance fires are a major cause of residential deaths. See link below.

Here is a link that might be useful: % of deaths due to different causes of residential fires

If anyone wants to better understand the role of nationally recognized construction "Evaluation Services" in design specifications and building codes, the link below might be helpful.

Notice the comment about CSA International:
"Don't assume because it's in Canada that it won't be acceptable in the U.S."

Here is a link that might be useful: Evaluation Services

Again,

Dryer boosters are prohibited under every model electrical, building , and mechanical code in the United States in Residential applications.

If any claims otherwise and without knowing that the products they are specifying ARE NOT LISTED then they should be looking for another profession.

UL DOES NOT LIST ANY dryer booster fans.

UL only list electrical motors...which have NEVER BEEN EVALUATED in assemblies manufactured for residential dryer boosters.

Such silly arguments mounted by MacV only go to show why code officials so often need to reject such ridiculous product specifications that DO NOT EXIST by unqualified 'design' professionals.....

Apparently we have run into a common misunderstanding about how products and systems are approved for use under ICC codes. I will explain how the process works for those who might actually want to know but I don't expect to convince Manhattan42 of anything nor would I wish to. Letting him persist in his confusion is the best retribution I can imagine for the over-the-top, in-your-face, disrespect he shows for the knowledge and opinions of others.

Because a code does not specifically mention a device or system as being allowed, or does not establish performance standards for it, does not, in any way, prohibit it's acceptance by a building official. Obviously, building officials need some kind of reliable evidence that a proposed product or system is suitable for use in a project but they are free to choose what information they believe is relevant. After all, ICC only writes and sells the codes; municipalities and states adopt, modify, interpret, and enforce them.

I have already quoted (above) section R104.11 of the IRC that makes it clear that the IRC does not intend to "prohibit any design or method of construction" provided that it has been "approved". The IRC defines the term "approved" as "approved by the building official". It does not mean approval by the ICC, ICC-ES, Testing Labs or any other entity outside of the local agency responsible for issuing permits. The IRC further requires that the building official's approval be "as a result of investigation and tests conducted by him or her, or by reason of accepted principles or tests by nationally recognized organizations."

In the past, UL has tested, passed, and "Listed" (i.e., published the results) dryer booster fans using their own test standards but it no longer does that. CSA International is accredited in the US by the International Accredidation Service (IAS) as a "Testing Lab" (TL) and accredited by OSHA as a Nationally Recognized Testing Laboratory (NRTL). CSA Int. is the equal of Underwriter's Laboratories (UL) in every way in all countries. For many acceptable construction products it is the only source of testing, Listing and acquiring a Mark. That is currently the the case for dryer booster fans and CSA Int. has used UL's standards to test these devices. They have passed certain models and "Listed" them. A CSA Int. certification or Mark This is all a building inspector needs in order to be able to accept these devices for a residence, however, that official may want to see additional evidence. Therefore, acceptance of these devices depends entirely on the judgement of the local building official.

In order to assist local building officials in their decisions, the ICC Evaluation Service (ICC-ES) reviews information submitted by a manufacturer regarding a product or system and decides if they think it complies with ICC codes. There is no ICC code requirement that a product or system receive an ES report in order to be accepted for use by a local building official, in fact, very few products and systems have been reviewed by ICC-ES. No type of fan or fan driven exhaust/ ventilation/hood system or appliance has been reviewed. ICC-ES makes all of its reports available to the public but it does not "List" or apply a "Mark" for any product or system like a TL does although they sometimes establish their own standards if they do not already exist. The ICC-ES reports are intended to assist in the determination of whether a proposed product or system is code compliant. Therefore, the absence of an ICC-ES report in no way prohibits the use of any product or system in a residence. It would not be possible to build a house if that were so.

In the end, it is the building official who must decide what complies with the law in his/her jurisdiction with the assistance of information from the owner, the builder, state licensed design professionals, manufacturers, ICC staff, ICC-ES, industry organization specifications and standards, and Testing Labs.

The truth is that some building officials accept dryer booster fans and some do not, and it is possible that other local or state ordinances, codes or code amendments might restrict their authority to accept them, but there is no prohibition of the use of these devices by any national consensus code published in the US.

My advice to anyone who wants to better understand the IRC (or any other code) is to carefully read the first two chapters (Administration and Definitions), and highlight the important text before jumping into the sea of prescriptive provisions in subsequent chapters.

I also advise you to highlight the most restrictive wording or dimensional limits and to pull out the code book whenever an important issue arises rather than relying on your memory or the off-hand comments of others which are often wrong. Write the your findings down with the appropriate paragraph numbers so you can back it up later. The last code compliance summary I gave to a building official was 7 pages long for a 3 unit dwelling.

Using a computer based version of the code can lead to mistakes because provisions can be misinterpreted if you are not aware of the heading the sub-text is under and that is often off screen. It is also sometimes difficult to read two-column text on a computer screen. Codes are designed to be read in book form and often the computer versions refer to the printed version as being the authoritative version. I want to see the real thing.

Highlighting and tabs are essential for understanding the code. I'm not making this up. I learned from some of the best code consultants in the US (they're all dead now) and their code books were a mess of tabs and notes. Every time the code is revised I have to go though the new book and highlight the important provisions and add tabs (you can often buy pre-labeled tabs for specific codes). At last count I had 33 national building codes and 10 UL Fire Resistance Directories going back to 1970, not counting the city codes that were in effect before the national codes appeared.

By the way, if anecdotal evidence means anything to anyone, when I asked FanTech for copies of the testing certifications for their dryer booster fans, they said the company gets such requests every day, especially from building officials and that they had yet to hear of a booster fan being rejected by a building official anywhere in the US or Canada. Somebody somewhere is making things up and I doubt it's Fantech.

"Dryer boosters are prohibited under every model electrical..."

Sorry. The NEC is silent on this.

Care to find the cite in the NEC you claim prohibits dryer booster fans?

Remember, that which is not prohibited IS ALLOWED.

The other thing that people seem to misunderstand about dryer fires is that they are not likely to start in a lint filled duct where there is no ignition source but in the dryer itself where any restricted air flow can cause the inside of the dryer to become overheated which can cause stress on the electrical parts which can eventually lead to a fire in the clothing or in excess lint within the dryer which can cause a flame to shoot out the rear of the dryer (if the transition boot is not properly attached) and set fire to adjacent materials.

Of course, many dryer fires are simply caused by an electrical malfunction of the the drum-drive motor and are unrelated to the vent system.

The most effective way to prevent dryer fires is to provide safety features in the dryer that can detect lower air flow or excess heat or smoke and shut down the drum-drive motor and heat source and sound an alarm. The CPSC has been aware of this problem for a decade but no agency has formulated a higher standard.

In the meantime, other than the obvious step of keeping the ducts clear. the best precautions are to install a smoke detector above the dryer connected to the house detector system, keep combustible materials away from the dryer (especially at the rear), avoid drying rubber-backed materials or clothes that have had contact with gasoline or solvents, and firmly secure a metal duct transition boot to the dryer.