Charles, Vent tubes are a great way to provide outside air and I know a lot of commercial greenhouses in this area that use them in the summer. I have talked to the greenhouse owners and managers about them, and with our winter wind. They get too much extremely cold air pushing into the greenhouse when it is not wanted. The result is they seal them up the outside louver during the winter and use them just to recirculate the air inside the greenhouse during the winter.
The idea of a tube to pull the air down from above and mixing it with cooler air from outside, that offers me the option of getting the hot air high in the greenhouse mixed with cold outside air, to provide way to help reduce the heat load in my greenhouse. I am looking at some ideas like this combined with some solar storage. I figure if I combine several ideas together they will do what I want to cut the winter heat load when the sun is shining. When I get some things figured out I will post all the ideas I have gotten on my web site and what I am going to do in my greenhouse. Next winter I will post how well the various ideas worked. Right now with the warm weather we are having I have started to open up my greenhouse and turned on my ventilation fans. Problems for this year are gone, and we will see how the system I install takes care of them next year. thanks, Tom Hillson On Mar 23, 2007, at 5:36 PM, Charles M. Ufford wrote: > Hello Tom et al, > One way of bring in a little cooler air might be to use some Jet > Fan tubes and a fan from the outside. Typically the fan is overhead > in the middle of one far wall. When cooling is needed, a solenoid > pulls open the metal louvers, the fan just inside kicks on and blows > outside air into a plastic tube usually about 1 1/2 feet in diameter > with two rows of holes near each other to direct where you would like > the air to go. You could also have a low power motor open a solid > louver outwards as another option. The latter version would seal > better where there are cold, strong winds. > > One negative of setting this up as we have them at work, is that > there would be a large open area in the wall where cold wind could > blast in as the fan is mounted a few feet away from the louver (for > air mixing) and really cold air does drop down when the vent is open > (you can see the fog dropping right down and can see the crispy > plants right where this air hits). Our setup with fans/large tube > might be too large, but there may be smaller systems that can be had > for smaller houses. If the fan were mounted and sealed directly on > the wall in front of the louver, then only the air coming out of the > vent tube would get in. > > If you wanted to pull down heat from above but didn't want to cook > things below, it might still be good to have a tube pulling air down > from above and be directed underneath, but have a small vent from > outside be pulled through another tube and mix with the above air. A > thermstat of sorts could be placed in the air stream coming from > above (after the mixing zone) that could open or close the spot that > allows the cold air in, keeping it from getting too hot. Otherwise > maybe putting some cold water through pressurized mist right in with > the hot air might help in keeping it from getting too hot. If a vent > tube were put on the floor just inside the wall, then water could be > misted or cold air mixed right inside this tube, and the adjusted air > could be sent down the length of your house, moving up from the floor. > hope this helps, > charles > -- > charles ufford > oriskany, ny usa > > _______________________________________________ > the OrchidGuide Digest (OGD) > [email protected] > http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
