Don't know if this would be a problem for you guys but venting into the
attic space is a really big NO-NO for those who live in areas where the
attic temperature can go below freezing, particularly for extended
lengths of time.
What happens is that the moisture in the air from all the sweaty ops who
have been following live scores and realize they're 5% behind the leader
will condense on the underside of the roof, etc and will freeze. Over
an extended period of time quite a lot of frost/ice can build up.
On the first warm day of spring, guess what - it starts dripping or
maybe even it all lets go. Either way, you've got some water or a lot
of frost and ice where you don't want it. If the attic has been
insulated with blown or poured cellulose fibre, the water will soak it
and start leaching out the fire retardant chemicals. This has two
undesirable results, one minor and one major.
The minor one is that the fire retardant salts may soak through the
ceiling material and form small stalactites. (I have actually seen
this. My mother was NOT impressed with the insulation job I did for
her.) While these stalactites are good conversation starters, they get
unsightly after a while as they keep growing.
The major one is that your insulation will have poorer fire retardant
performance, not what you really want.
So, carry the vent duct either through the wall at a gable end or
install a proper roof vent and attach the vent duct to that.
This all assumes normal ventilation of the attic space. If you have big
fans up there venting to the outside then you could be OK.
Nothing wrong with cellulose fibre as insulation - you just have to keep
it dry. In fact, I've seen photos of a house where the roof caught
fire, for reasons which I don't remember, and the roof was totally
destroyed. When the fire got down to the cellulose insulation, the
retardants put it out and the rest of the house was still FB. Don't
think it would have fared as well with other forms of insulation.
Blowing moist air into a crawl space during cold weather is another
no-no unless the crawl space is very well vented to the outside.
Typically, people board up the crawl space vents in winter because they
feel that the floors will be cold if they don't. If the floors have
been properly insulated, they'll be fine. However, if moisture is blown
into poorly ventilated crawl spaces, it will hang around and condense on
the floor joists. So, now you run the risk of having soaking wet floor
joists all winter long with ice maybe part way up them and water soaking
into the fibreglass batt insulation and reducing its insulation
effectiveness, thereby making the floors colder and the joists subject
to rot.
Once again, vent moist air directly to the outside rather than into the
attic or crawl space and save yourself a lot of potential grief.
Nothing wrong, though, with venting it into a heated space where it
won't condense, such as other parts of the house. The amount of
moisture will be far less than that produced by cooking or bathing
(unless, of course, there's one hour to go, you're 100 Qs behind and you
desperately need that VE7 mult).
73, Jim Smith VE7FO
David Fuller wrote:
> I have a large skylight that runs from the 8ft ceiling to the pitched roof
> through the attic. I put in a vent up there in the side of the skylight
> tube into the attic and ran small flex duct over near the attic vent which
> is about 25 feet from the shack. There I installed a box enclosed exhaust
> fan and wired it with a simple cooler thermostat in the shack. It comes on
> automatically and pulls the hot air out of the room. This works well
> because I barely hear the fan noise in the shack.
>
> For more volume you could use something like a swamp cooler fan box and
> exhaust the air outside. Grainger is a good source for various industrial
> fan systems. That is where I got mine.
>
> They also make cooler updraft vents that vent from the room to the attic
> space. You could put large fan exhaust on the attic space and it would
> quietly draw air out of the room though the automatic updraft vents. The
> vents will self close when the fan is off.
>
> -Dave NN5K
>
> On Sun, Nov 23, 2008 at 10:48 AM, K5RC <tom@k5rc.cc> wrote:
>
>> I went to single-band amps earlier this year and mounted them in a closet
>> next to the shack with the front panels mounted in the wall. I put a
>> bathroom exhaust fan in the room venting up into the ceiling. The fan is
>> noisy, but, compared to the noise of 6 amps, it is not a problem. I had to
>> put a small window air conditioner in the window in the closet for contests
>> during the summer. Otherwise, leaving the door open works for keeping the
>> room at an acceptable temp. Since my shack is built inside the garage, the
>> open closet door gets cool mountain air most of the time and cold air in
>> the
>> winter. Elegant but simple solution for me, mostly to get rid of the noise
>> and heat inside the shack and hiding hundreds of feet of cabling.
>>
>> Tom Taormina, K5RC
>> Virginia City NV
>> -----Original Message-----
>> Message: 6
>> Date: Sat, 22 Nov 2008 16:40:02 +0000
>> From: "K1TTT" <K1TTT@ARRL.NET>
>> Subject: [CQ-Contest] shack air flow?
>> To: "YCCC" <yccc@yccc.org>, "reflector cq-contest"
>> <CQ-Contest@Contesting.COM>
>> Message-ID: <C2B7926912E8418393EBA3AEFEA16B7B@k1tttibm>
>> Content-Type: text/plain; charset=US-ASCII
>>
>> Normally in m/m contests we end up with windows open and a big box fan
>> running to keep the temperature down in the shack. I am looking for
>> something maybe a bit more elegant. Has anyone used those small high
>> velocity ducts to either blow in air or as exhaust ducts? I am thinking
>> that one in each corner sucking out the hot air may be best, then I could
>> blow it down into the crawl space or upstairs to reducing heating need
>> during cold weather contests. This would have to go above a drop ceiling
>> and preferably not be very noisy.
>>
>>
>> David Robbins K1TTT
>> e-mail: mailto:k1ttt@arrl.net
>> web: http://www.k1ttt.net
>> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>>
>>
>>
>> ******************************************
>>
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