can't quantify it for you, but my hunch is that a 4" ceiling vent relying on stratification and not mechanical force is not large enough to overcome static pressure and induce significant flow through a 4" ground intake--particularly if the ground intake is long enough to cool incoming air appreciably. A venting skylight might be a better option, assuming summertime solar gain and wintertime thermal loss were factored in. regardless, many variables need to be considered...<br>
<br><br clear="all"><b style="color:rgb(0, 102, 0)">Alan Abrams</b><b style="color:rgb(0, 102, 0)"><br>Abrams Design Build LLC</b><br style="color:rgb(0, 102, 0)"><i style="color:rgb(0, 102, 0)">A sustainable approach to beautiful space</i><br style="color:rgb(0, 102, 0)">
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<br><br><div class="gmail_quote">On Mon, Aug 29, 2011 at 8:20 PM, Frank Tettemer <span dir="ltr"><<a href="mailto:frank@livingsol.com">frank@livingsol.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi All,<br>
<br>
Here's a ventilation question, for all the fresh air fans on this list.<br>
I'd like to use gravity ventilation, and I need to plan a way of opening and closing the vent.<br>
<br>
We're building a small straw bale home for a couple this year that has engineered trusses.<br>
The upper cord, defining the roof surface, is 6/12 pitch.<br>
Inside, the ceiling in one area of the house is a 3/12 pitch.<br>
The walls are 8'-3" at the truss plate, and the central high point in the ceiling is 10'6".<br>
The home will be heated with an ESSE wood cooker, and has a 4" diameter ABS pipe emerging from the floor, behind the ESSE, bringing in fresh air, from below ground, and will be ducted to the combustion air inlet on the wood stove for the winter.<br>
During the summer, a 4" TEE in this air pipe will allow earth-cooled outside air into the home.<br>
(We've provided condensation drainage, as well as a straight clean-out, from the outside of the home, to deal with potential mildew troubles.)<br>
<br>
What I would like to do is provide a 4" exhaust vent, up at the peak of the interior ceiling, to complete the ventilation scheme, which relies on gravity to power the flow, i.e., hot ceiling air vents upward, through the attic space, while colder earth-tempered air is drawn in from the outside in the North shadow, to the centre of the home, near the stove.<br>
<br>
I know that while windows are open, the earth-tempered air may not flow inward with any serious pressure.<br>
But the hot air, at ceiling height of 10'-6" will surely flow upwards and out, no problem.<br>
<br>
Back to my original question around ventilation. How do I open and close that 4" ceiling vent?<br>
Is there anything on the market that has very positive closure, and could be used? A good closure system will be necessary during the long winter months, here in Ontario, near Algonquin Park, which has weather similar but colder than Ottawa, Ontario.<br>
<br>
I'm sure this has been done before, and there must be a practical way to control this venting.<br>
Any ideas?<br>
<br>
Frank<br>
<br>
-- <br>
Frank Tettemer<br>
Living Sol ~ Building and Design<br>
<a href="http://www.livingsol.com" target="_blank">www.livingsol.com</a><br>
<a href="tel:613%20756%203884" value="+16137563884" target="_blank">613 756 3884</a><br>
<br>
<br>
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