I have an exterior attic vent under the over hang of my roof. The vent is 4" (I think) in diameter. The vent is one of those air-intake vents with rain guards.
For the last few days it's been below freezing. On those cold days, icicles appear on the rain guards. The house has an air exchanger (non-heat recovery) which has been running on those cold days. The house seems to retain a lot of moisture as the windows tend to either have condensation or ice at the bottom when it's really cold outside. Also, the house is heated with electric baseboard heaters.
Before I climb into the attic, I was just wondering if the icicles on the exterior attic vent is normal? I'm a first time home buyer and I do not know much about attic ventilation. My concern is that there may be moisture build up in the attic.
Sounds like some of the humidity in the house is passing out of the vent and freezing. The whole moisture level in the house sounds like it needs to be studied. TB
Chris wrote in news:BBTrh.166183$YV4.155356@edtnps89:
Icicles from vents are not normal. Icicles obviously are water. Moisture vapor is water. Check out where your dryer is venting and if any of the piping for it is leaking. Bath fans as well.
I peaked into the attic. I just stood on the ladder with a flash light as I didn't know where would be safe to step. What I saw was a lot of blown, beige or grey insulation (I was wearing a mask). For the most part, the insulation is evenly spread out. The insulation is severval inches thick and three is a plastic sheet under it. I can see light from the various vents, but I couldn't see the actual vents, only the big vent at the peak of the roof.
The dryer vents through the main floor to the outside on the other side of the house, so it's nowhere near the vent. The bath fan is connected to a black pipe that goes straight up and through the roof. I turn the fan on and didn't see any insulation blowing around.
The wood joists appeared to be clean with no water damage. No signs of mold. There was some insulation clinging to the joists but I figure it got there when the insulation was installed?
I can see the tubing for the air exchanger. It's the grey, insulated soft kind. It was coiled all over the place. Most of the tubing was covered by the insulation. I couldn't see any obvious sign of leakage.
The air in the attic was cool. The outside temp right now is somewhere around -3 C (26.6 F). The air didn't smell musty.
What I figure is that the moisture in the house is rising and getting into the attic - perhaps through the attic door? The vent is right across the attic door. I'm not sure how else the moisture can be getting in there.
If there is too much moisture in the house, perhaps the air exchanger is inadequate? It's an Enviro ENV-100 and the house is roughly 1400 sq feet (each floor is around 700 sq feet). It seems that the blowing in vents inside the house are working very well. But the suction vents are not very strong. Perhaps the air exchanger does need replacing - perhaps with a heat recovery model?
ARe you sure that's an attic vent you're looking at? You only talk about a single 4" round soffit vent, which would be very unusual. Normally, there would be many of them, or continous soffit venting along a thin strip. A single one exhibiting this sounds more like a bathroom fan vent or similar.
Also, what's with the air exchanger? From the description of the house, it sounds like it's an older one. Unless you have a very tightly sealed house, where special steps are taken to make it air tight, which is not common, the house will have enough air leakage so that no air exchanger is needed. Folks go around trying to seal up drafts, not use a fan to suck in cold air, which is like leaving a window open. And if you do have one, I'd be damn sure it was a heat recovery one, especially with electric heat!
I'm sure it's an attic vent. I'll try explain why. The roof over hangs the house. On the underside of the roof, there is a white siding material with tiny wholes. The vent is on this white siding material. On the other side of the over hang are shingles. From a window across from the vent I can see duct work. When I was in the attic I didn't see any duct work over where the vent is located. The over hang part dropped below the floor of the attic.
The house is a semi an is 10-11 years old. The house is pretty air tight. There are some very tiny drafts that I have found, but haven't looked into them that much.
I should also mention that on the other of the concrete wall that separates the two dwellings is the same vent in the same location (relatively). My guess the houses are identical, just mirrored. When the icicles where forming on my vent, there were no icicles on my neighbour's vent.
Unfortunately, the darn air exchanger is very old. My guess it was installed when the hot water tank was installed. I had to replace the hot water tank already it was 10 years old and started to leak. I definitely know that the air exchanger is not an HRV model. I've started looking into getting a new air exchanger. I hope the installation is just as simple as replacing the old unit. Perhaps the installer would go in the attic and inspect the duct work to make sure it's ok?
Which makes it even less likely that the vent was put there for attic ventilation. The siding with the tiny holes on the soffit is continous soffit venting. Normally, that is all that is used to provide the soffit venting. It makes no sense to then just add this one 4" additional vent.
On the other side
Not clear here on what you are seeing here, but if you can see ducting connected to the vent, again this is not normal for attic venting, for which there is no reason to connect ducting.
When I was in the attic I didn't see any duct work over where
Probably 95%+ of houses don't have nor need an air exchanger period.
Yeah, since it's below the floor of the attic, I can't really know for sure. But, I think you are right, it must be a vent for something, I just don't know what.
If that is the case, then the icicles are fine because that means that it is venting moist air from inside the house and doesn't mean there is moisture in the attic?
What is typically connected to a 4" vent? I thought the black, vertical pipe (like the kind the trap for a sink is made of) in the attic was the vent for the bathroom fan, but I think that may be the vent for the plumbing? I think drains need a vent to properly drain right??
You are definitely right. I stuck my hand out the adjacent window and could feel the exhaust from the bathroom fan. So, the icicles are not a problem then.
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