We have a moisture buildup in the attic because it appears that the house
does not have enough roof vents (four vents for 1,800 sft house with the hip
We would like to install a power vent with a humidistat.
Can anybody tell how much noice such a vent makes? Is it noticeble? How
often does it turn on?
What is a good vent brand?
yes they do make noise. It is noticable but for the most part not
objectionable. However (in my opinion), you are better off to correct the
intial problem (lack of vents) than to try to band aid it with "more power".
I have had 3 power vents in 3 houses by 3 manufactures and all three froze
up in under 2 years. My bad luck? I don't know but I won't waste my money on
them any more. I also worry about them being fire hazards when they freeze
up. You are also more prone to ice dams in the winter with inadequate
ventilation and power vents don't run in the winter. Do humidistats work in
I strongly suggest you forget the power vent idea and move on to fixing
the real problem. The correct fix will be cheaper and work better in the
BTW why a humidity sensor? What is adding moisture to your attic that
would trigger it? You should not have anything adding moisture.
While I would consider a second opinion (and fresh ideas) he may be
right. Just adding a power vent will not change that however.
It may well be possible to do what is needed and still maintain a good
If it were up to me to put up with a vent where it may detract from the
looks of the roof or not have it and detract from the function of the roof,
I would choose function.
I agree, but still don't understand why doesn't a power vent solve the
problem. It looks for me, that a power vent provides an additional air flow
in the same way as a regular vent does, but since it has a motor, I may need
Of course, if the vent freezes in the winter, I don't want it.
The reason I started thinking about a power vent, is that I found on one web
site that a power vent is the best option for the houses with a hip roof.
Maybe it was the web site of a company who sells it ): ....
My stuff on ventilation says that a power vent does not
reduce the amount of free ventilation space. It seem like
it would, but that is not what they say. I presume you are
talking about a roof mounted fan since you have a hip roof.
The quietness of the fan depends on the roof construction
and a lot of factors. My fan makes very little noise and is
noticeable in only one spot (about 4 foot by 4 foot) if you
listen hard. It mades a bit more noise before I put up a
sound reflector/absorber. This was simply a sheet of
material hanging 1-2 feet below the fan more or less
parallel with the roof and does not interfere with air flow.
The term "freeze up" in common usage means that the shaft
binds tightly and stops turning. It has nothing to do with
freezing temperatures or freezing water. The vent won't
freeze in the winter. Winter, however, does mean that the
motor won't turn on, since power vents are controlled by
thermostats usually set to about 95 or 95 degrees to turn
on. So your power vent definitely won't provide more
ventillation in the winter than if you just left the motor
Your best solution is to add more ventillation grills in the
soffits (smaller more closely spaced are generally better
than a few large grills) and add some more passive roof
vents. Get a hand out from your local BORG or read the
information on a package of asphalt roofing to find out how
much free ventillation you need. It is possible that your
problem, if real, is caused by the soffit vents being
blocked by insulation.
well, let me start by saying that overall, you really do not want a
power ventilator. We had one at our cottage in ontario on lake huron
(really hot attic). We had friends who also had one, and it "froze"
(Motor burnt up). After hearing their story (house caught fire) we
installed a manual motor control with a heater coil, so if the motor
took excessive power, it would just trip the switch. We came home to
the cottage one day, and my 14 year old noticed the switch was "off".
He went into the attic and discovered the motor totally frozen, and
there was no real cause for the freeze up. The motor was new, and the
unit itself was only a year old. Anyway, they are a real pain in the
a** and I would not reccomend buying one.
Ventilation is a two part process. First there has to be a vent out to
get rid of the air. However for that to work there also has to be vents
letting air in.
Another very big factor is the location of the vents. If the locations
short circuit or leave dead areas, those areas will not be properly vented.
The shape of your roof and attic area in relation to the location of the
inlets (lower located vents) and exhaust (high vents) determine this.
I suspect that since the roofer suggested you need some venting on the
front of your roof, that there may be a dead area situation and just adding
a power vent will not change that. At best a power vent may increase the
flow so you can get buy with lest total vent area. It also could create a
short circuit and actually reduce the effectiveness of your vent system
(although I would believe this is the exception, not the rule.
In short, I suggest having someone who knows what they are doing take a
look at your situation and make a second recommendation so you can confirmed
the first of put it in doubt.
I've got one to reduce the temp in the summer. I can hear it, but only
if I listen for it.
I am curious if you've tried to identify the source of the excess
moisture. Generally, one gets moisture problems when warm, moist air
hits a cold surface. Adding extra vents certainly will help remove the
moist air faster, but one has to wonder why it is there. Have you
looked to see if any of the bathroom fans, or other fans, are venting
into the attic?
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