Denise,
Before I glazed my greenhouse with lexan, I had much heavier vents
and I had to cover them in the winter as the strong winds on the
plains would push the cold under them. It does not take much
extremely cold air to cool a greenhouse down fast. That is one of the
reasons most people I know around here try to completely seal their
greenhouses in the winter. Infiltration of very cold air is a
disaster. I can tell you that 15 years ago, I did not seal my
greenhouse like I do now and someone opened one of the lower vent
doors I had to close my vents, as a result I lost over half my plant
collection. Since then I have been completely redoing my greenhouse
and completely sealing it in the winter.
Unless I had some mechanism to lock the vents to create a baffle to
protect the vent, just putting vents on the roof is not a good
solution for me. I think in areas with less wind or less extreme cold
weather your solution would work well.
Tom
On Mar 22, 2007, at 9:36 PM, Denise Nash wrote:
> Hi Tom -
>
> My roof vents don't leak, I think because they are too darn heavy to
> have the wind blow them open. Have you thought of using a different
> material (other than Lexan) for glazing on your roof vents? Mine are
> double paned glass with an air space.
>
> ~Denise
>
> Thomas Hillson wrote:
>
>> Mark,
>>
>> Unfortunately, I tried moving the air to the floor, but the times I
>> tried it, my entire greenhouse went over 90 degrees, way to hot for
>> my cool growing species that I like to keep no more than 60 to 70
>> this time of year. If I did not have a varied collection of orchids
>> this would be easier, but I have over 250 genera and lots of hybrids
>> in my collection. Most of them are Paph species and Paph hybrids, I
>> also have a lot of Pluerothallids, and a heterogeneous collection of
>> other things. I love the unusual, that is part of why I like orchids.
>>
>> I like the idea of more roof vents, but I want to work on a way to
>> shield them from the north and west winds we get here as I found them
>> to drive the cold air under roof vents in the winter. I had some roof
>> vents on my old greenhouse, but I did not replace them when I put new
>> lexan the greenhouse two years ago as I was looking to save heat and
>> keep the greenhouse warmer. The problems I have found with my
>> greenhouse is you want to keep the heat in at times and you want to
>> get rid of it other and it is really hard to do both well. Any one
>> have any roof vents with a baffle or other protection around it or
>> any ideas on how to seal a vent better than the normal ones that just
>> lay on top of the greenhouse.
>>
>> I am enjoying this discussion, I hope we can come up with some good
>> ideas that will help more people.
>>
>> thanks,
>>
>> Tom
>>
>>
>> On Mar 22, 2007, at 12:58 PM, [EMAIL PROTECTED] wrote:
>>
>>
>>
>>> Thomas,
>>>
>>> Another tactic for "I am both trying to keep the cold out and the
>>> very
>>> expensive heat generated by my furnace in the greenhouse" on cold
>>> days
>>> ("A week ago it was still over 100 in my greenhouse but the outside
>>> temperature was 10 degrees.") is to have several fans at the top of
>>> your
>>> green house that blow down. This blows the hot air down to mix with
>>> colder sitting near the floor. Warming up the cooler air or
>>> cooling the
>>> hot air depending on how you want to look at it. The effect is a
>>> closer
>>> temperature more homogeneous from top to bottom in the greenhouse.
>>> This
>>> tactic also decreases the amount of time your heater runs if the
>>> thermostat is located closer to the floor then the top of your
>>> greenhouse. I do this in my own greenhouse.
>>> I can't add anything to the ventilating to the outside
>>> suggestions you
>>> have gotten expect it sounds like you either need more vent fans, a
>>> larger vent fan, some passive roof vents, or a combination to tackle
>>> your problem of " They barely keep my greenhouse temperature from
>>> going
>>> over 110 at 8 feet." If it is possible to install in your
>>> greenhouse I
>>> would go with adding roof vents that open and close with changes in
>>> temperature that Denise Nash talked about, more energy efficient.
>>>
>>> "If you have anything you are using or any ideas let me know, and
>>> lets
>>> keep this discussion online, I would like to see if we can generate
>>> something useful for the archives." I applaud you for saying this.
>>> It allows everyone to learn at the time of discussion, and into the
>>> future. Discussions can lead to new ideas. If Ed Merkle and Denise
>>> Nash
>>> had only sent you private e-mails of their excellent posts, we
>>> would all
>>> be the poorer and the OGD would be relegated to news posts and
>>> squabbles. Nothing wrong with the news posts mind you, but
>>> discussion
>>> is where the OGD gets interesting.
>>>
>>> Mark Sullivan
>>>
>>>
>>>
>>> _______________________________________________
>>> the OrchidGuide Digest (OGD)
>>> [email protected]
>>> http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
>>>
>>>
>>
>>
>> _______________________________________________
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>> [email protected]
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>>
>>
>>
>>
>
>
> _______________________________________________
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