Hi everyone,
I used to post as “Paula” but I guess we had to get new logins, so I switched to Paularado. We’re still working on our log home in the mountains above Denver/Boulder (started 4 years ago). Hopefully a few of you still remember me!
Anyway, we decided to install a hood over our range that requires 6″ ductwork. No problem, we can vent it straight up and out the roof (probably about a 14′ run). Everything seemed easy enough until my neighbor told me that he has to tape his damper closed on his hood or it will rattle incessantly in the wind (there is no shortage of wind!). I’m wondering if anyone has any ideas about this. Part of the ductwork runs through a closet, so I’m wondering if we could put a manual damper on the “chimney”….or even better, is there an electronic damper we could add? Are there vent caps that are better than others?
We bought a Sirius SU3 hood, if that matters.
http://www.siriushoods.com/products-wh-su3.htm
Thanks All!
Paula
Replies
Anyone? I'm the only one who lives in a wind tunnel? LOL!
Paula
Hey Paula, you might get an answer yet, some folks here actually have jobs
and have not seen the post yet..:>}"
That's why I cleverly bumped it at the end of the day.
http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemKey=5C524
or if that link doesn't work:
http://www.grainger.com/Grainger/wwg/start.shtml
and then type in Grainger Part # 5C524
this damper must be accessible for cleaning, inspection, and replacement.
carpenter in transition
Paula,
The hood vent is only one piece of the problem; what about your bathroom vents? I close them off evening when we have decent winds to prevent them rattling. They have a damper similar to the Fantech part at Graingers. I have been considering a couple of options for a major remodel;
1) A powered damper such as at http://www.famcomfg.com/Dampers.htm.
2) Tamarack http://tamtech.com/ has several options, including their "Cape Damper" which is supposed to be quieter, and seal better, and the "Preventilator 2" http://www.rewci.com/prev2througw.html, http://www.energyfederation.org/consumer/default.php/cPath/30_426_102, which may not still be available.
For a fireplace chimney one option is "Control Top Cover" http://www.controlcover.com/, Lymance available from several sources including http://www.volko.com/lyemance.htm, or http://www.chimalators.com/chimalatorpics.htm for a closeable cap. I am worried that it may not draft well when open as something such as a Beldes inc Belcap (No web site 800 456 8803), or a Vacu-stac, but an active draft inducer might work with a closable stack.
You can also get a lot of noise from your DVW penetrations through the roof; I was considering using cheaters (Air admittance valves) http://www.studor.com/index.htm
If you use any of these I would appreciate knowing whether they work or not.
Hilltop,Those are some great links. Thank you so much for the information! I have got to believe that other people will benefit from this thread.Our fireplace chimney does make a little noise every once in a while in the wind, but it is a 14" pipe for a Fireplace Xtraordinaire, not a regular masonry fireplace. I can live with that sound; it isn't a rattle or a whistle and that fireplace gives us so much in return. It's simply amazing.Thank you!!!
Paula
Hi Tim,Thanks for the suggestion. I'm going to have to look at that.I appreciate it!
Paula
Paula, I am down the hill and have a vented hood with the fan unit on the roof (its a 1200cfm w/10" pipe),,, the thing has been there for 20+ years and the only thing you can hear is the rain/hail hitting it .Your neighbor may have a crappy unit..
Bud
Seb,Your experience is encouraging. Thanks so much for the feedback. I cannot believe the amount of wind we have here. We used to live 6 miles further north off the same hwy we do now, and even that place didn't have as much wind. I guess it's a topography thing. I'm so glad we built a log home with a serious glu-lam roof system. Nothing creaks, even in 90 mph wind. Add in dense pack cellulose and radiant heat, and the house is QUIET. I think I'd go nuts if after all that effort, the stupid hood was rattling in the wind! Paula
Paula,
Hello from a wind-blown carpenter from Laramie. The big log homes we worked on along the CO/WY boarder were high on some very windy ridges. Very windy even by Laramie standards.
The main problems we had with vents had to do with the windward side of the house being pressurized while the off side of the house had somewhat of a vacuum. The roof line effected which rooftop vent was typically pressurized and which was typically drawing air.
Vents exiting the pressurized side would exert pressure on the vent flaps causing whistles and air leaks, not to mention the vent fans have to overcome the force of the air that wants to come in. Basically a hard to win battle. About all you can do is get a vent flap that seals very well. We would sometimes add a thin stick-on foam weatherstrip around a flap to quiet it and help the seal. It's much better if possible to reroute side vents to the low pressure or neutral side if possible.
Vents on the low pressure side of the house would draw air very well and sometimes drew too much, essentially keeping the vent flaps open as air was sucked from the house. During the summer this might not be bad, but in the colder part of the year it can result in a great amount of heat loss. We've added a bit of weight to a flap to keep it somewhat closed until needed, balancing that with a more powerful exhaust vent to overcome the resistance. This would be a good place for a powered flap.
Vertical vents were a source of whistles and banging flappers. Keep in mind that wind blowing across a vent opening creates a vacuum the faster things blow, thus creating flap rattles as the wind gusts. Sometimes altering the cap on the vent reduces the vacuum.
On the roof, if you have a few possible locations for a vertical vent, it might be a good idea to put up a temporary pole with a fabric streamer to act as a windsock. The streamers will show how hard the area is hit by the wind coming over the roofline and can help when deciding between two locations.
Also keep in mind that a high pitched roof can experience a large pressure differentiation from one side of the peak to the other. A vent on one side would be on the high pressure side while just a few feet away on the other side it's sheltered from the high-velocity wind gusts and is much more user friendly.
Assuming you are limited to one location for a vent penetration, you're stuck with optimizing the vent flapper or replacing it with a wind resistant one. We usually still had to mess with almost all vents, even the wind resistant ones. I'd start by adding a thin foam ring to dampen the sound and increase the seal. This may require altering the hinge and counter balance. We would joke about a $20 flapper being worth $200 by the time we reworked them. Then try various vent caps to minimize flapper "flap."
I'll throw out another solution to the flapper flap that is for the worst situations if an automated flapper isn't an option and requires the most work. Using a plastic flapper, a small (1/8" round) high powered magnet is attached to the flap and another is taped to the outside of the flapper housing. By varying the distance of the two magnets the flapper is held tight enough that it takes the force of the vent motor to open it. Once the flapper is open the magnets are farther apart and essentially no longer exert closing force on the flapper and thus don't reduce the efficiency of the fan. Like I said, this takes some messing with to work and you have to be a tinkerer at heart, but it can work very well.
In really high wind areas, windows seem to cause all sorts of leaks and whistles, as you're probably very aware of. These are probably harder to fix, but that's another topic altogether. :-)
Don't get blown away and have fun figuring out your homes pressure areas.
:-)
Don
Hi Don,Many thanks for taking the time to explain your experiences with wind. It's funny because I was thinking.....isn't anyone from Wyoming reading this thread? Surely THEY know what to do! LOL! (I have a friend who lives on Lake Hattie).The wind is predominantly from the northwest, but if there is an upslope storm coming, it can come from the east. If it is Chinook winds (the strongest) they come from the south. I guess it's more like a big swirling vortex I live in actually, not a wind tunnel! So, I'm not sure that there a pressurized vs non-pressurized side. It changes. You gave me some great ideas to think about. I really appreciate it! The foam and magnets are intriguing. Paula
Edited 11/10/2005 10:15 am ET by Paularado
Paula, Up in Wyoming our wind is almost always from the same direction so it's hard to imagine wind from everywhere. :-)
The foam really does quiet a damper quite a bit, even those plastic "quiet" dampers. Another trick that we've used with good results is increasing the sound resistance of whatever material you have around your vent. A bare vent pipe can be quieted down a bunch with a fiberglass wrap and doubled sheetrock if it runs just under a sheetrock ceiling or wall.
Many times the metal shroud just above the hood, if applicable, needs free air movement between it and the vent ducting, but that doesn't mean the metal duct can't be wrapped in a sound deadening material that doesn't effectively insulate (surgical tubing).
Yet another thing almost forgotten, is to avoid dampers close to earspace. For instance a bathroom vent damper is often in the bathroom fan enclosure and can easily be heard, but a remote flapper, or better yet a remote fan, greatly cuts down on the noise.
:-)
Just a quick update, we installed the hood with fingers crossed, but, alas, it rattles. So, we're planning to explore the great ideas offered here. I will report back. Do you ever feel like the butt of a joke played by mother nature? Here we spent big bucks to build a log home with a mega strong glu-lam roof system that makes no noise in the wind. Our french doors are outswing so they blow in and seal themselves in a windstorm, and yet......after all of that....some stupid kitchen hood makes an annoying rattle and sucks the heat out of your house. Sometimes you gotta wonder if someone out there is laughing at you! :-)Paula
Thanks for bringing this topic up. I live in the Ridgecrest Wind Festival (1/1-12/31 annually) area. 25-30 kts summer, up to 100 kts winter. This will definitely help as I build my house.
Erich
Paula,
Is it the noise that bothers you, or the lost heat? I live high atop a hill in SE WI in a "loose" house (20-50 MPH winds the norm in winter) and have the same problem and cured it with double dampers, one spring loaded, the one on the roof facing mostly downwind ie South and down.
WSJ