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Posted by DerbyDad03 on November 2, 2007, 8:41 am
On Nov 1, 1:01 pm, cle...@nortelnetworks.com (Chris Lewis) wrote:
>
> > On Oct 31, 9:34 pm, cle...@nortelnetworks.com (Chris Lewis) wrote:
> > > Over thirty years ago, we found that some thermostats start
> > > at around 50F with an offswitch, and others don't have an
> > > offswitch, and start around 36F.
>
> > > We wanted the 36F ones to keep a cottage just above freezing.
> > In reading some of the questions that get sent to the Home Repair
> > section of our local newspaper, I think I recall something about
> > issues with condensation if the temperature is kept below some magic
> > number (50?).
>
> This sort of thing is going to be very dependent on conditions.
> Not just environmental, but building structure and ventilation.
> As a simple example: our garage.
>
> It's vapor-barriered (6 mil plastic) and insulated with decent attic
> ventilation. When we moved in, the floor was just gravel. Unheated.
> Approximately two days per year (usually in the fall), there was a
> moisture problem that caused bare metal (eg: my tools) to begin to rust.
> Visible condensation everywhere.
>
> A few years later, we had a concrete floor put in with a layer of foam
> board under it. Moisture/rust problems _completely_ disappeared. There
> are now heaters in it, and I only turn them on when I'm going to be
> working in the garage for extended periods during the winter. When the
> heaters are off, the temperature in the garage can drop as low as -30C
> or lower during the winter. Zero moisture problems (except when
> the ceiling vapor barrier fatigued in a few places and fell through,
> and the attic got too warm - icicles and condensation at the
> ruptures.)
>
> The cottage is similarly well insulated and vapor barriered (kraft
> insulation). We heated the cottage itself to 4-5C. At first there
> was a moisture issue _under_ the cottage - concrete block foundation,
> dirt floor, and we also kept the pump area warmer by enclosing the
> section with a double "curtain" of 6 mil plastic and a fan heater
> modified to operate at around 5C. But that was eliminated by
> power venting the crawl space outside of the "bagged" zone.
>
> The only moisture deterioration problems were in the cottage ceiling due
> to "cathedral ceiling" (2x6 Cedar T&G, 1" foam, sheathing then shingle -
> no ventilation), no sunlight due to trees (roof stayed damp) and
> (eventually) carpenter ants. Everything was torn off but the T&G,
> "joists" were laid over the T&G, bat insulation with a 2" airgap
> under the sheathing. Moisture problems eliminated.
>
> Anyone saying "don't go lower than 50F" or something like that will
> be doing a CYA because they don't know whether it really will cause
> a problem or not. Whether it causes a problem is determined by
> the building and weather conditions.
> --
> Chris Lewis,
>
> Age and Treachery will Triumph over Youth and Skill
> It's not just anyone who gets a Starship Cruiser class named after them.
Thus my reason for adding the last line to my post:
In any case, the OP might want to do a little research and determine
if "just above freezing" is the correct temperature for his location.
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