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Posted by on January 20, 2007, 10:01 am
Chris wrote:
> Al Bundy wrote:
>
> >
> >> Hello,
> >>
> >> 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.
> >>
> >> Thanks,
> >>
> >> Chris
> >
> >
> > 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?
>
> I guess I should contact my local heating store?
>
> Chris
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!
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