Do OAKs for electric dryers exist, if not, what other options are there?

Hello
Our electric clothes dryer is in an air tight bathroom we made in the basement. We did install a window so we can leave it open a crack and close the door to that room so the rest of the basement is fine.
Our dryer like most does not have an air inlet pipe with an air tight body so an OAK would not work very well.
Therefore the air tight room seems to be the best solution.

The metal door with weather striping makes a good deal.
See pic below.

I've investigated whether I could connect an outside air source to about 4 electric dryers now and not found any that were easily modified for this. You could potential cut some holes in the outer sheet metal and then connect an outside air source to the dryer's interior air inlet but it would not be pretty or straightforward, not as far as I've seen anyway.
You could do the airtight room as Don suggests.
You can also invest in a ventless (condensing or heat pump dryer) that does not need to exhaust outside. Bosch and LG make ventless and other manufacturers are making heat pump units. These will heat the air in the area around your dryer though. In my case, I use our HP Geospring water heater to recover some of that heat.

I'd look into an "HRV" or Heat Recovery Ventilator. http://www.popularmechanics.com/home/interior-projects/how-to/a149/1275121/ This would at least allow you to recover heat from the outgoing air and with the proper dampering should leave the house with a positive pressure. Plus you could run it at set intervals to help relieve SBS.

I vent our dryer to the basement. My lint trapping setup needs an overhaul, but the heat stays inside. And the humidity doesn't seem to be an issue in winter. We're likely not as tight as you are though.

semipro said:

u can also invest in a ventless (condensing or heat pump dryer) that does not need to exhaust outside. B

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Had one of these before, wouldn't recommend if u don't have to the maintenance on them is a pita.

Our dryer and wood furnace is in the same unfinished walk out basement. Once shoulder season arrives and winter sets in, we only do laundry on cool & cloudy days. We disconnect the dryer vent and leave the outside pipe unrestricted. This functions as a simple OAK because the outside louvers don't seal 100%. Then we install a 5" metal elbow and pair of dead panty hose on the dryer pipe. It catches the majority of the residual lint, and blows all the heat and humidity into the house. We have a simple 8" blower (huge muffin fan) that helps distribute wood heat to the other end of the house. We just run it while drying laundry to distribute the heat and humidity and the whole house smells like fresh laundry & dryer sheets. A panty leg lasts a good 2-3 weeks. A full pair of hose lasts 4-6 weeks. After the first few loads the pores clog up a bit and they filter really well.

What can be done with out to much expense is make a passive make up air system. Bring in out side air through a very long duct system . This can be set up up and down a wall or back and forth across ceiling then terminate that into a large box on floor from the box you install another duct back up to almost the ceiling this is your make up air system . By using a very long air intake ducting it allows that cold out side air to temper quite a bit before being spilled into home. This not a new idea and I can't take any credit for it. Think I read it back in the 70's - Mother Earth news or Popular Mechanics. The longer the initial run of ducting the better.

Swedishchef said:

The venting inside isn't an issue. I could if I wanted to. For me it's more the idea of trying to get some outside air directly to the dryer. Aightight homes aren't all they have cracked up to be! As Corey mentioned, proper installation of an HRV would be the perfect setup. But there's no company that installs them properly around here. The balancing of the machine is done by a company that drives through every 3-4 months.

Andrew

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We have an HRV too, I put it in myself when we built. Didn't think there was much complicated about it as far as balancing goes. Just kept flows & runs as unrestricted as possible. Then each inlet or outlet inside has a vent thing you can open or close as needed to fine tune if needed. It would be a bear to retrofit though, if trying to duct to each room. You could maybe run a couple of larger duct runs to the couple of largest spaces in the house? Airflow has a way of balancing itself out, to a certain extent. But - if you duct the dryer vent inside, wouldn't that mean you wouldn't need an outside air feed?

Well, yes, if you send inside air outdoors, it needs replaced by outside air coming inside. I had a couple of points though. One was if you vent indoors, you wouldn't need replacement air. But also, it wouldn't need to be a big ' balancing act' to come up with a replacement air setup, that only let's air in when needed. I'm picturing something like an ordinary dryer vent with a flapper that opens to the outside when the dryer runs, but in reverse so it opens when there is a pull from inside. Then there was also a suggestion above about using some piping to allow some heat exchanging. I think. The exchanger in my HRV is very simple, and it can only get so much warmth out of the air before it exhausts it. We actually keep it off most of the winter since even though the incoming air gets warmed some by outgoing air, the incoming air is still pretty darn chilly when it's minus temps outside.

I'm thinking on the same lines of what maple 1 said.
Keep the dryer where it is, build a simple air tight room around it (see how easy I made that sound ) Then go out through the rim board of the house, should be able to access this from the basement, with a length of duct work that would connect to, and allow air to be drawn into the room with the dryer when it's operating.

I never considered my house to be overly tight, I'm fairly sure it isn't since I've never put any effort into it (I believe, as a carpenter, being air tight creates a lot of issues in the long run) but a couple weeks ago, the fire was just catching, already established a draft, wife turned on dryer and bathroom vent, draft started reversing . Took a second to figure out what the heck was happening, easy fix, Crack window, done....

Completely agree on the excess moisture thing, that is to be avoided no doubt. I read a lot of posts during the winter though about people complaining their houses are too dry in the winter and all the things they do to add moisture. Those are situations where venting things indoors could get two birds at once.

jb6l6gc said:

Had one of these before, wouldn't recommend if u don't have to the maintenance on them is a pita.

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I have to disagree a bit. We've been using a Bosch condensing dryer for over a year now and our maintenance amounts to monthly cleaning of the heat exchanger module and its pre-filter. They take about 15 sec. to remove and 5 minute to clean in our kitchen sink.
Yes, this is more work than just cleaning the lint filter on a standard dryer but we have no vent ducting to clean. Clogged dryer vents decrease efficiency and are a major cause of household fires.
Keep in mind too that Heat Pump Dryers are relatively new and are different than the condensing dryers you (likely) and I use(d).
http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/heat-pump-clothes-dryers

semipro said:

I have to disagree a bit. We've been using a Bosch condensing dryer for over a year now and our maintenance amounts to monthly cleaning of the heat exchanger module and its pre-filter. They take about 15 sec. to remove and 5 minute to clean in our kitchen sink.
Yes, this is more work than just cleaning the lint filter on a standard dryer but we have no vent ducting to clean. Clogged dryer vents decrease efficiency and are a major cause of household fires.
Keep in mind too that Heat Pump Dryers are relatively new and are different than the condensing dryers you (likely) and I use(d).
http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/heat-pump-clothes-dryers

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Wait till your drain line clogs Trust me had it happen lol. Wow a year with no problems I expect at least 10. Don't get me wrong Bosch are good would not buy another lg or Samsung product though. From personal experience I think lg stands for lousy goods

semipro said:

I have to disagree a bit. We've been using a Bosch condensing dryer for over a year now and our maintenance amounts to monthly cleaning of the heat exchanger module and its pre-filter. They take about 15 sec. to remove and 5 minute to clean in our kitchen sink.
Yes, this is more work than just cleaning the lint filter on a standard dryer but we have no vent ducting to clean. Clogged dryer vents decrease efficiency and are a major cause of household fires.
Keep in mind too that Heat Pump Dryers are relatively new and are different than the condensing dryers you (likely) and I use(d).
http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/heat-pump-clothes-dryers

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4% of the fires (in one of the recent studies) . . . definitely not up there with cooking, heating equipment and electrical . . . but it does come in at the #6 slot for top causes of fires in the U.S.

http://www.nfpa.org/research/report...roperty-type/residential/home-structure-fires

Warm_in_NH said:

I never considered my house to be overly tight, I'm fairly sure it isn't since I've never put any effort into it (I believe, as a carpenter, being air tight creates a lot of issues in the long run)....

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There still is a lingering feeling on building new houses along the lines of "tight, but not too tight - the house has to breathe." That simply doesn't work. Any house that is uncomfortably dry inside during winter is a house that leaks far too much air. Outside air leaking in to replace conditioned air leaking out flushes out the moisture produced inside by human activity. If you add moisture to inside air, such as with a humidifier or unvented electric dryer (unvented gas dryer would be a hazard), that moisture ultimately goes out through the walls and into the attic, where it too easily can condense on cold surfaces and be absorbed into the wood, which will result in rot and mold when the weather moderates in spring, unless the house is so leaky that the air leakage dries out the wet wood fast enough as things warm up. Vent that dryer directly outside, always, unless the dryer is a condensing dryer that sends the water down a drain.

There is simply no way to build in the "right" amount of "leakiness" when building a new house. The house doesn't have to breathe. The occupants do, while the house has to avoid moisture accumulation problems. Leakage is driven by wind pressure and by air density difference between cold outside air and warm inside air. You can't build in the proper amount of air leakage that will give the occupants the right amount of fresh air to breathe in any particular weather conditions, other than by dumb luck. In cold, windy weather the house leaks the most, and when it's a windless day in the 60s the house doesn't leak at all. In between it's anything, and inevitably wrong, and can't be controlled. The only building strategy that works is to make the house tight as possible, make sure interior air is kept out of the walls and attic space, and provide mechanical ventilation at a controlled rate. In a heating climate that would be done by a HRV, for heat recovery. With the HRV balanced for normal operation (in=out), it will go out of balance when an exhausting device (eg. dryer, range hood) depressurizes the house. Having a wood stove in a very tight house makes it difficult to light off with a dryer going without an OAK, and even then cracking a window open until draft is established is a good idea.

My buddy just built a house here in NH in an air tight fashion using multiple layers of rigid on the exterior, something like 8" of it, taped and sealed! The roof is similar but thicker. He's near 60 now and we bust each others chops, as I keep telling him I'm going to charge him an arm and a leg to fix all the rot and moisture issues he built into his home when it rots out in 10 years. He swears they've been doing in Alaska for years with great results, I say it's because it gets cold and stays cold in Alaska, the constant swings in temperature and humidity here is what's going to ruin your plan.

I suppose in 9 more years we'll sit down with a beer and one or the other one of us will be able to say, "I told ya so!" (I hope it's him), until then he's heating the place with radiant floor heat very efficiently.

That design they've been using in Alaska, with all the foam insulation outside of the sheathing, keeps the sheathing well above the dew point of inside air, preventing condensation problems. I think that's what is called REMOTE, developed from the PERSIST method. This link describes it:
http://www.cchrc.org/remote-walls

The use of a lot of rigid foam insulation outside of the framing and sheathing works in all climates for moisture management.