Long Duct Run for Vented Dryer vs. Condenser Dryer

sfgal_jroMarch 18, 2007

I need to buy a compact size washer and dryer to go in a hall closet (I have only have 29 1/4" between the back wall and the closet door).

I can add whatever electrical service is needed and can vent outside through a somewhat convoluted run of ductwork:

The duct would go up the back wall of the closet, then between the ceiling joists for about 6 feet, then jog over to go between the next set of ceiling joists for another 8 feet and then through the outside wall. All told, the duct would run about 18 feet, with 4 turns.

Some of the sales people I've spoken to have recommended that I go with a condenser dryer instead of a vented dryer. Their rationale has been that the length of the duct and the turns required will (1) impact the efficiency of the the vented dryer enough that the condenser dryer will be equal in drying speed and (2) create a fire danger because of lint build up.

I currently have an Equator EZ 3600 CEE washer/dryer combo that has a 1.9 cu. ft. drum and runs on 110. I know the Asko, Bosch and Miele condenser dryers all have a larger drum capacity and use 220 versus the 110 of my current machine, but I'm a little hesitant to go with another condenser dryer because my current machine takes 2 hours to dry 2 bath towels.

I live by myself, so I tend to do smaller, more frequent loads, but I do have king-size sheets.

Any thoughts on whether to go with a vented or condenser dryer would be much appreciated. Frankly, the cost to add the ductwork won't be a driving factor if I'll get better performance from a vented dryer.

Finally, if you have any recommendations on Asko, vs. Bosch, vs. Miele, that would be great too. I'd be looking at the following models:

Asko: W6222 washer with either the T712 or T712C (ventless) dryer OR the W6461 washer with either the T731 or T741 (ventless) dryer.

Bosch: Either the WFR2460UC (Axxis+) or WFL2090UC (Axxis) washer with either the WTA4410US or WTE86300US (ventless) dryer.

Miele: W113 washer with either the T1312 or T1332C (ventless) dryer

Thanks in advance for your help!


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I would still go vented if you can swing it. A total length of 18 feet isn't that much, but 4 turn are more than normal. I don't believe the Bosch is rated for more than 3 bends, but with some tricks it would probably work just fine. The Miele can without question handle the 4 bends and 18' length. Not sure about the Asko.

The key is doing the duct installation with much care. Use smooth 4" rigid duct for everything possible (if you even do that for the connection to the dryer even better). What would greatly improve the venting to the point where atleast 3 of the bend aren't much more restrictive than straight vent is to use the long radius dryer ell. It requires more space, but well worth the trouble if it fits. It would also make cleaning much easier as the brush won't need to make sharp bends. For cleaning look at the linteater system.

You can download the manuals for all the dryers your considering and see the manufacturers venting specifications. If you stay within their bounds it should work as they set these limits as part of the dryer's UL certification.

Here is a link that might be useful: Dryer Ell

    Bookmark   March 18, 2007 at 10:31PM
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gordonr, curious why would suggest trying to swing the vented unit vs. the ventless? I am considering an Asko T712C ventless for my application. Will I lose perfomance with the ventless unit? Or is there some other reason?

    Bookmark   March 18, 2007 at 11:06PM
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The main reason is drying speed and ease of use/maintenance. I also assume vented dryers are less expensive. With a vented dryer you can pretty much always count on the dryer being done before the next wash load; don't believe that is universally true with a condensing dryer. Also once or twice a year you clean your venting with a standard dryer. With the right tools it takes next to no time. I believe lint has to be cleaned off the condensing fins on a fairly regular basis with a condensing dryer. Have heard that is easier on some models vs. others.

To be honest I love the idea of a high efficiency condensing dryer, but those are very expensive and not available in the USA. I've read that in Europe V-Zug and AEG have (or had) heat pump based models available, but the cost is crazy so not many have been sold. So many home appliances have gone to great lengths to improve their energy efficiency due to government standards over the years with some exceeding the baseline (Energy Star), but not the dryer.

Hopefully someone who uses a condensing dryer will respond with their experiences.

    Bookmark   March 19, 2007 at 12:23AM
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You also have to empty the water collected from a condensing dryer. Also thought some condensing models need or work better if they can be connected to a cold water source to assist in the condensation process. They just sound more complex.

Given your small loads maybe a condenser would work out. Once you get the venting in, a regular dryer just seems so much simpler.

    Bookmark   March 19, 2007 at 12:31AM
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The reason I end up with 4 bends is the initial bend from the back of the dryer to go up the wall, the bend from the wall to go through the ceiling (the dryer ell would work great there) and then, unfortunately, I need to move the duct from running between one set of ceiling joists to the next set (there are recessed lights in the way) and that requires the duct to turn to the left to move through one joist and then turn again to run between the joists to the outside wall.

I did download information from the various web sites, but after my experience with a sales guy this afternoon, was curious as to what people's actual experience has been. I was concerned that just because the documentation said it was ok to do, that it was possible that the drop off in performance might be such that the condenser might be a better way to go.

For those that might be interested:

Asko's documentation says up to 60' with a max of 4 bends (subtracting 4' for each 90 degree bend). I spoke with one of their customer service reps who felt the 712 was a better choice than the 731 for my application(apparently the 731 was initially designed for a max of 22'). He also indicated that because the Asko washer only intakes cold water and uses its own heater, it can take up to 2 hours for some of the wash cycles to run.

Miele's documentation says up to 65', but doesn't specify a maximum number of bends. It says to subtract 1-2' for every bend and anywhere from 2-12' depending on the type of wall vent you have. The biggest deduction comes from exhausting it either left (20') or right (33') instead of from the rear.

The Bosch documentation has the most restrictive venting guidelines - it has a max of 30' with no 90 degree angles or elbows and only 6' with 3 angles/elbows. Based on what it said, I'd have to go with the condenser version if I went with Bosch.

The store I was at did not carry Asko, only Bosch and Miele. I got the sense he was really pushing me toward the Bosch (possibly because I don't have enough room for the larger Miele models).

Assuming there's not a huge drop in performance, I'd prefer a vented model, so I'm leaning toward either the Miele or the Asko. Our local inspector (SF) also told my contractor that there are booster fans that can be added to the duct to increase the airflow (the web site for the dryer ell had one.)


    Bookmark   March 19, 2007 at 12:43AM
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Sounds like the vent will take an ugly route to the outside. Not all venting specs talk about this, but there is an airflow penalty for doing back to back 90 degree elbows without much straightaway between them. With regard to specs, I'd tend to believe the manufacturers. Shorter and more direct is always better (and have shorter drying times), but they have no doubt tested their products at the far end of the spec and found air velocities and static pressures acceptable. Can't believe any reputable manufacturer would want to be exposed to the wrath of class action lawsuits and the like if their product didn't meet spec and caused problems (e.g. extreme lint build-up and fires).

I'd also continue to explore the condensing dryers just so you know your options. Over the years on this board there has been a number of posts regarding these units. I remember some brands had better designs than others. They were not all created equal.

    Bookmark   March 19, 2007 at 1:59AM
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I have an Asko condenser dryer and I would recommend a direct vent model if you can swing it. I have the condenser because of a unique situation, but I would always opt for regular venting if I could.

It's not that the condensing function doesn't work, it does, most of the year. (And it can keep up with the Asko and Miele washers, just fine.) But it has its own set of challenges.

Cleaning the condenser fins is the nastiest, most disgusting job in my household and it has to be done about every five to seven loads, not the once or twice a year as it recommends in the manual. And a condenser model never really dries out inside so the machine is constantly on the verge of mold problems. So much so that in the summer, though I only use it for a few minutes for each load (I hang out everything on a line) I set a small heater in the dryer drum and run it for half an hour after the last wash load has been processed just to try and get the machine dry inside. I have replaced the felt lining at least six times in the fifteeen years I've owned the machine. And twice a year I break the whole thing down and completely disassemble to dig out the fine, fugitive lint that accumulates inside. When I mean disassemble I don't mean just opening the back, I mean take it apart into a pile of pieces on the floor.

It also generates a surprising amount of water vapor. I have a collection of antique books and I monitor my interior Rh with hygrometers, so it's not just my imagination. The additional humidity is not particularly problematic in the winter when this wood-heated house gets as dry as the Sahara but in the summer it can be a problem as we don't have a/c.

And that brings me to the main functional problem: The condensers work best when the ambient air temps and the temp of the heated air within the dryer have a big spread. In the winter my house is usually about 60F so there's no problem. I live in the NE and during the summer the ambient air temp in my house can easily be 75-80F, or even higher. Under those conditions the spread isn't wide enough to be efficient at low dryer temps. And usually it's a hot, humid, rainy (and therefore rotten outdoor drying) day when I finally get desperate enough to use my dryer to fully dry a load, only to find that it takes forever to accomplish its task under those conditions. If you live in an air conditioned house, or in a really dry area, this would not be a problem for you; but since the dryer also throws out a fair amount of heat you will pay to run your a/c to remove the heat you could have just sent out the exhast run of conventional dryer.

In short, if there is no other choice, then a condenser dryer will do the job, but in every other circumstance a direct vent would be better, IMO.

For a regular dryer you could increase the vent size and add an in-line booster fan to assist in good ventilation. Also plan to have easy cleanouts to make that task less onerous.


    Bookmark   March 19, 2007 at 2:50AM
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I saw a dryer on the Lowes site when I was shopping for my washer that said it was a long venting dryer. It claims you can run a duct up to 150'. I don't know how big it is or anything else, just wondered if this might be useful for you. I checked the model number, it is DLSR483EGWW. I hope this is helpful, I certainly would not want to mess with the kind of cleaning people have mentioned here for the condenser dryers.

    Bookmark   March 19, 2007 at 7:53AM
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Thanks for the tip on the really long venting GE dryer - unfortunately, I don't have room for that size machine. It's 28 1/4" deep and once you allow for the duct connection at the back of the machine, I don't have enough space in my closet.

Relative to other posts about condensing dryers throwing off a lot of heat and not working well when there's not a lot of difference in the ambient air temperature - I live in San Francisco, so it rarely gets colder than the 40s or warmer than the 70s. In fact, since our summers can be cool and foggy, I've been known to have to turn the heat on in August. So on the positive side, a machine that throws off heat probably wouldn't be too much of an issue.



    Bookmark   March 19, 2007 at 10:40AM
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We just went through the same exercise regarding venting. We are also considering the exact same appliances because of limited depth. Additionally, there is one additional suggestion that no one else has mentioned. A company called Fantech offers in-line and outside mounted booster fans for weird or long dryer runs. I spoke with a tech guy at the company and he seemed pretty knowledgeable. The fans are pressure activated, so only run when the dryer is turned on. I don't know if you need this extreme a solution, but the price for these is only about $200, about the same difference between a condenser dryer and a vented one. BTW, there are more detailed installation instruction regarding venting on Miele's website. You add a certain length for each bend to calculate a totaly effective vent length.

I am very interested in which brand is your top contender. We may have to eliminate the Bosch because it doesn't vent on the right. We've got an 11-year old Asko dishwasher that has run without any repair and performs well. However, looking at this site and other places on the internet, Asko reliability and service seem to get LOTS of complaints. Otherwise I would go with the Asko, but it looks like we are going with Miele.

Finally, if you are in San Francisco, where are you shopping for appliances? We are on Russian Hill. Please post your choices when you finalize your decision.

    Bookmark   March 19, 2007 at 5:49PM
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You may win the award for the most unconventional venting path, but I'll stress again that if it falls within spec, don't worry about it. Even if you can manage only one of your elbows using the long radius ell, every little bit helps. You seem to be well within the venting limits of the Miele and Asko. The Fantech booster fan certainly has it's place, but you probably aren't even close to needing this added complexity. If your really worried you could always buy the dryer of your choice and mock-up your venting before it's concealed in the walls/ceiling. Dry some loads and see how it does. If you want to go wild you could have a good HVAC person measure the static pressure in the ducts using a manometer to make sure the venting isn't too restrictive. In the unlikely event you need the fan, it's still easy to install.

    Bookmark   March 19, 2007 at 11:53PM
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If there's nothing else I've learned during the course of my renovations, I've learned that everything ends up being more complicated than you expect. Once you open up the ceiling or the wall, there always seems to be something in the way of what you want to do. A floor joist where the tub drain needed to be, pipes where I wanted recessed lights to go, and now the recessed light over the tub is where it would make sense to run the duct. I can hardly wait to get to the kitchen renovation!

I spoke with a rep in Miele's technical service group yesterday. Initially he was telling me he thought what I wanted to do entailed too long a stretch of duct - that it would reduce the performance of the dryer. I told him I expected that it would not be optimal performance, but what I was trying to determine was whether it would reduce it to the extent that a condenser dryer would have the same performance.

He didn't seem to understand what I was getting at, so I gave an example: If the vented model has 15% better performance than the condenser model and the venting I'm doing reduces performance by 15%, then the condenser model would be generally equivalent, but if the vented dryer's performance is 50% greater, the same 15% reduction in performance would still mean the vented dryer was a better choice. I asked if he could give me any information about how much better the vented dryer's performance was than the condenser model and how much the venting I was considering would reduce the vented dryer's performance. At that point, he said he wanted to talk with one of the senior technical reps and put me on hold.

When he came back, he told me that the dryer was rated for up to 60 feet (which I already knew) and that I should be fine with what I was planning on doing. He also told me that the sr. rep had indicated that having a condenser dryer in a closet could be problematic because it puts off a lot more heat than a vented dryer - you'd need a lot more air circulation into the closet with a condenser dryer. The closet I'll be putting the w/d into is 68" wide by 29" deep, so the extra heat and air circulation need may not have been as much of an issue for me as it might be for others with a more confined space.

One learning that I took away from this: if you start to get the sense that the technical or customer service person you're talking to may not be as knowledgeable as you'd like, ask to talk with a senior rep. Like anywhere else, initial phone calls will be answered by more junior staff who will route the more complicated issues to more experienced staff.

I've decided to go with a vented dryer, and now just need to decide between the Miele and the Asko. I'll let everyone know which one I end up with.


    Bookmark   March 20, 2007 at 10:33AM
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I have a fairly long run, 1 90- out the back then into 3' of straight pipe, then into 10 feet of flex duct with two bends in it (one 90 and the other more of a sweeping 45) That hooks into a 90 then onto a 3' section of straight pipe going through the wall to a vent cap. Its on a miele and works perfectly well.

    Bookmark   March 20, 2007 at 3:50PM
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As noted in my post above, I've narrowed it down to the Miele and Asko models (the Bosch specs indicate a more limited length of duct than I need).

Expo Design Center (on 40th in Oakland) carries Bosch and Miele, but doesn't carry Asko. BSC Culinary (aka Bob's Supply Company) on Mission in SF carries all 3 brands. There are probably others as well, but those are the ones I'm familiar with. I expect each company's website has a feature that allows you to identify local retailers that carry their products.

I'll let you know what I decide.


    Bookmark   March 21, 2007 at 10:08AM
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We also went to BSC to shop. You might also want to check out Cherin's on Valencia. They carry everything, too. We bought all our kitchen appliances from Cherin's 10 years ago and were satisfied. BSC also seemed to be good when we visited them a few Saturdays ago. And they had freshly baked cookies. Don't know how they compare with Cherin's in terms of prices. I think we're going with Miele, but I'd still be interested in knowing what you choose. Good luck with your decision.

    Bookmark   March 27, 2007 at 2:51AM
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Hi bestefar,

Funny you should mention Cherin's - I stopped there last Saturday and was going to write a note suggesting them as another option - they only charge $130 for delivery/installation of the W/D, whereas I was quoted as much as $300 for for the same thing by another store.

I've decided to go with the Miele W1113 washer and the T1312 dryer. I've ordered a few of the "dryer ells" suggested by gordonr. My contractor had never heard of them and thinks they're a great idea (he actually said it was a little embarrassing to have a client know more about the latest technologies than he did - thanks gordonr!)


    Bookmark   March 29, 2007 at 9:53PM
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Hi Jan,
Thanks for following up. Good to know about the delivery charges. You can't go wrong with the Miele.
A plumber came over yesterday to look at my installation. He didn't seem very experienced in dryer vents and wanted to run it under the house, which is what I was trying to get away from doing, and had never heard of the dryer ells. He said it would be two guys and an all day job. By SF plumber prices I figure that's $1,500. Yikes.

Where did you order the dryer ells?

Best of luck. This website is a great resource. Thanks to all.

    Bookmark   March 31, 2007 at 2:19PM
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Hi bestefar,

I couldn't find a local distributor, so I ordered the dryer ells online (see link below). After talking with my contractor, I also ordered one of their dryer boxes - it allows space for the flexible connection to the dryer to store nicely between the studs without worrying about it being kinked up behind the dryer.

I feel your pain on the cost - if it's any consolation, my total costs are far more than that! Because I'm taking one of my bedroom closets and opening it to the hallway, I also had to add the water and electrical hookups. (Not to mention the drywall work to close off the closet on the bedroom side, open the ceiling to run the electrical and duct work, build a wall for the new closet ...)

Would have been far easier (and cheaper!) to just leave it in the kitchen, but I've got a very small galley kitchen and a w/d just takes up too much space. On the positive side, I'm gaining additional storage in the new closet and I'll have more space in my kitchen. (I just keep repeating that to myself over and over.) Once this is done, I'll start planning the kitchen renovation. I'll be sooo glad to have everything completed!

Here is a link that might be useful: Dryer Ells

    Bookmark   March 31, 2007 at 3:39PM
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Just be aware that the condensing dryer will add a TON of humidity to your house, so you probably want to add some dehumidification to prevent mold, dust mite growth, etc.

    Bookmark   April 2, 2007 at 6:50PM
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bestefar, Bosch vents out the right side and can be run up to 30 feet with 4 90 degree elbows.

    Bookmark   August 12, 2007 at 8:31PM
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