: venting rangehood fan and cold air
2007-02-15, 10:03 PM
We built a new home 4 yrs ago, and we where our own general contractors. We lived on the yard the house was being built and were there on a daily basis to make sure things were done correctly.
Now, our rangehood is on and outside wall and is vented to the outside. In winter time there is quite a bit of cold air that comes in, and sometimes there is even ice on the mesh filter. To me, this does [B]not[B] seem normal.:confused:
Does it sound normal to you?
No, that's not normal. I've always had outside venting range hoods (others are mostly useless) and have one currently. Had one in Calgary for 7 years (where it was cold as Manitoba, brr ;) ) and have one currently in Toronto - it's been close to -20C at night for several weeks now and very windy with wind chills as low as -38C).
There should be a "flap" (or two) in the line that prevents this backflow. Sometimes during strong winds, the flap will "chatter" (you can usually hear this). Your flap may be stuck open. You may also be able to hear the flap close when you turn the fan off after being on.
PS, the current one we have vents out through a "diffuser" something like a roof vent (actually it is a roof vent). This can help dissipate the wind/flow. I just felt my hood and its "inside temperature", not cold at all, but it's not one of the inexpensive range hoods, it's a "Best" built-in hood - operates sort of like the attached photo - "disappears when closed", but ours is actually sleeker with the part that pulls out only being 1" thick, instead of what looks like 4-6" in the photo. The "guts" of the hood are "hidden" in the cabinet above the part that pulls out.
Do a search for roof vents - there are all kinds of designs.
Both of the homes we've had over the years had ranges that vented outdoors. Even in the coldest of weather, I never experienced such a draft. Like 57 says, it sure sounds like a flap is stuck open.
2007-02-16, 07:56 AM
same here, the duct work also has insulation wrapped around it as well.
2007-02-16, 01:34 PM
Or the flap could be missing. It is not uncommon for cheap plastic flaps to break off or come loose with time. It would be best to replace the outside vent with a better quality unit.
2007-02-17, 12:32 AM
well, it definetly sounds like something is wrong. I know the outside cover with the louvers are all there. I really think there isn't any flaps in the ductwork. I know it isn't an overly expensive rangehood, but we can take the front part of our cabinet off [it has a built in look, no metal can be seen unless you look from underneath] and see the hose, I am pretty sure it is just a flexible hose.
Now, the trick is to motivate my hubby to look at it! That is another question!
2007-02-17, 10:12 AM
Based on your initial post, you have vented your range hood through an exterior wall rather than the roof. Is that correct?
You also state that the louvres are closed on the outside cap. Do they open when you turn your fan on?
As 57 stated, your fan should have a damper on it right at the range hood itself regardless of the cost of the unit. The damper typically has a rubber or foam gasket to soften the noise of the damper closing. This should be closed when the fan is off to prevent backflow of outside air.
Turn your fan on and check to see that the louvres are open. Then turn your fan off and listen to see if you can hear the damper close. Then check and confirm that the louvres are closed.
You may have to take the cabinetry off and look at the range hood to confirm that the damper is
1) present and
2) functioning properly
If it isn't there then I would suggest installing one and redoing the ductwork at the fan if required.
Try contacting the fans manufacturer's website or help desk. Good Luck.
2007-02-17, 12:10 PM
Most exhaust fans (and dryers) have a built-in damper to block air and then there's an outside damper (or louvres in your case) to block more air. Sometimes the inside damper is left out (by mistake) or taken out (because there isn't room). In that case you need a better quality wall cap with a better damper.
On a completely different note -- if you have a modern air tight house and the fresh air intake is closed then outside air will be pulled in from things like the kitchen fan exhaust. Those little louvres arent't very airtight and the air has to come from somewhere. If you open a window a little and the problem goes away then there's your problem.
2007-02-17, 01:37 PM
thanks for the words of advice,,, I will check it out! And yes, it is vented out on the wall, not the roof.
2007-02-18, 07:13 PM
ok, checked the outside vent while the fan was running and the louvres where opened and it all looked fine there.[I could even smell the macaroni my daughter was cooking]
So, next step is to get hubby to take the decorative front off so we can get a closer look at the insides. I couldn't hear any damper closing when I turned the fan off, so I am pretty sure it is lacking one.