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John,<br>
I stand corrected. I was only considering thermally driven flow and
overlooked stack effect. Mea culpa.<br>
Bob<br>
<div class="moz-cite-prefix">On 10/28/2012 10:46 PM, John Straube
wrote:<br>
</div>
<blockquote cite="mid:508DEDF9.7000002@gmail.com" type="cite">
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<div class="moz-cite-prefix"><font face="Helvetica, Arial,
sans-serif">Hi Sacie<br>
I assume you have double-glazed low-e argon Pellas, with wood
frames?<br>
If you have condensation problems it is very likely too high
RH. I am curious about your comment that the RH is within the
recommended range.<br>
This could be ture, but is that recommended range might be
20%RH or 50%, since I have seen both "recommended" for the
Kansas climate. Have seen some significant condensation on
low-e Argon filled windows in a large multi-unit building
about 1.5 hr drive from Kansas City which was reported to
always be bad at this time of year.<br>
Condensation like this tends to be worse early in the season
as the moisture from building materials is released. In my
airtight home this delay is very noticeable (eg RH is
stubbornly high until January I find), and I have to ventilate
aggressively during this time period to keep my RH within safe
levels.<br>
As rough guidelines, when it is 30F outside, I would target
30%RH and when it is 10F, I would look for 20%RH. It takes a
while to ventilate down to those levels, but once you get
there it tends to stay.<br>
<br>
PS I have triple glazed foam filled fiberglass framed windows.
Condensation can be made to occur on these rather high
performance units merely by letting the RH ride up to, say,
50to 55% during 30F nights. The condensation quantity is
small but totally visible.<br>
PSS Bob's claim that windows leak outward in cold weather is
not true. It is often true for the second storey of homes,
but rarely true for the 1st floor of 2 stroey homes and almost
never true for windows on the windward side during windy
weather.<br>
<br>
<br>
<br>
</font>
<div class="moz-signature">Dr John Straube, P.Eng. <br>
<a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="http://www.BuildingScience.com">www.BuildingScience.com</a></div>
On 12-10-28 1:20 PM, Sacie Lambertson wrote:<br>
</div>
<blockquote
cite="mid:CAM6L0t4dz+GbamEYBVidUVg4Xvy2cNtv5HsEP+=uzGx=7Uiunw@mail.gmail.com"
type="cite">On Sun, Oct 28, 2012 at 10:36 AM, Bob klahn <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:Home-NRG@dnaco.net" target="_blank">Home-NRG@dnaco.net</a>></span>
wrote:<br>
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"> Lance,<br>
<br>
One guideline that has been implied but not stated in any
reply I've read is that whatever approach you choose, the
innermost pane must be the air-tightest to limit
condensation. The old "rule of thumb" was five times
tighter than subsequent panes, if there is any leakage.
This allows any leakage (drying) to be to the outside.<br>
</blockquote>
<div>Re Bob's note on tight windows, we're now moving into the
winter heating season. Our windows are starting to
condensate at the base on the inside. Many of you have
suggested this is the penalty of winter. Isn't there
anything I can do about it? With the windows I have? Or,
are there windows out there that don't condensate in the
winter? Are there windows that don't leak cold air to the
inside from the outside glass per Bob's dictum? Or is this
not a matter of tightness, but rather of the differences in
temperature?<br>
<br>
thanks, Sacie<br>
</div>
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