Ventilation 2002:


Many more reservations than expected during the winter of 2002 caused me to start planning further renovations to the Alberta Classic loft because, as it was, it obviously could not accomodate more than 170 birds. I talked this problem over with my friend, Tom, who thought that increasing the efficiency of the ventilation system would be enough of a modification for keeping these youngsters healthy and I would not need to increase the floor space. Regardless of how ideal one arranges a passive ventilation system, in which air keeps moving due to the difference in specific weight of warm vs. cold air, the variability of the climate will put definite limits onto this passive flow of air. I cannot imagine a chicken farmer, for instance, who would trust his birds to such a system although he certainly would like to keep his input costs low. He therefore uses a mechanical fan which allows him to control the flow of air and with it the health of his animals.

My friend, Len, told me about his brother in law, Cobus, who was to look after 20 000 chickens while the owner was away on a short holiday. The electric fan failed due to a power interruption and Cobus was not familiar with the emergency power back-up. Only a dozen chickens were still alive after a couple of hours and opening the barn doors to let fresh air in was obviously insufficient. Birds need much oxygen and will perish quickly without it. A good loft with the proper internal climate may therefore be at least as important as quality birds for flying performance.

I looked up an article of Tony van Ravenstein's ventilation system in the German weekly, "Die Brieftaube", and decided to embark on making the necessary modifications to the Alberta Classic loft.
The ceiling was closed and the loft was made air tight which has the further benefit of keeping mice out. It is recommended to allow the total air volume of the loft to be changed every 2 minutes without creating a draft. Our total volume is 13' X 32' X 6' or 2496 cubic feet. The fan would therefore be required to move 1250 cubic feet of air per minute.Please note that the equidistant holes cut into the ventilation shaft are getting larger as the distance from them to the fan increases. In order to have the furthest ventilation hole still suck air, the sum of the areas of all the holes should not be larger than the cross - section of the ventilation shaft. Our ventilation shaft measures 10" X 21" X 27 feet long. The cross section is therefore 210 inch2. The holes we cut 3 feet apart are 4"X4", 5"X4", 6"X4", 7"X4", 8"X4", 9"X4", and 10"X4". Adding these areas together gives us 196 inch2, definitely less than 210 inch2.

It is advisable to have the air intake as far away from the birds as possible and on the side opposite the perches or nest boxes. This, however, is not possible since we need perches on each side of the loft. Nevertheless, please note the down feather in the left perch is just hanging there - the perch being completely draft free. Air can be detected by looking at the other down feathers and their orientation relative to the red thumb tacks which fasten the thread to the down feather. Even the air intake on the top right and furthest from the fan is trying to pull in the down feather and is therefore functioning well.

A rheostat such as the one to the left can be used to adjust the speed of the fan. This helps us increase the speed during warm weather and decrease it during colder temperatures.
And here on the left is the finished loft for ca. 350 birds augmented by the new 12' X 14' hen section
( 168 ft2 or 15.63 m2 ) on the right. Please note that the nylon mesh surrounding the hen section is almost invisible and will require some study to see how suitable a material it is for this purpose.
The required perches will be moved from the main loft after the darkening period is completed and the "spring season" arrives.

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