FACT SHEET 2

5. The practice of using one individual light trap per fan carries over from the days when only 36 inch fans were used in houses. With the high performance 48 inch or larger fans that we use today, individual fan light traps generally do not work well. Even a 60- inch x 60-inch, 25 square foot light trap is likely to raise static pressure too high when put on one of today's tunnel fans.

4. The fan performance characteristic to look for in choosing a pullet house fan is a high airflow ratio. A high airflow ratio means that the amount of air the fan moves does not drop off that much as the static pressure gets higher. Airflow ratios in the 0.80 range are considered very good.

3. Because of fact #2, we must realize that when designing or retrofitting a pullet house you should choose a fan that holds up well under higher static pressure. Most well designed pullet houses have fans that are operating in the 0.15 to 0.18 inches of static pressure range when they are in full tunnel ventilation. The performance characteristics of the fan that you choose are very important in making your house operate properly.

2. Light trapping makes ventilation more difficult. Choosing a high efficiency, high airflow light trap goes a good way toward alleviating the problem. But we must take into account that even the best light traps will offer some resistance to airflow. As we apply light traps to cooling pads, fans, and inlets, fans must work harder and will give lower performance. This is an important fact to keep in mind when choosing light traps and fans.

6. Because of fact #5, the definate tread in the design of new pullet houses is the use of a false wall for light trapping. The false wall incorporates the light trap area needed, and is placed about five feet from the tunnel fan end, of the house. This allows all light traps to be utilized when less than all tunnel fans are being operated. It allows more light trap area, than the one light trap per fan method and is by far the most effective way to ventilate a tunnel pullet house.

7. Proper winter time ventilation has been recognized as an extremely important factor in growing a good pullet. Proper wintertime power ventilation allows us to bring cool air in high above the birds and not chill them. We can blend cold air with hot air and achieve the target temperatures we desire while maintaining good litter moisture and conserving fuel.

8. Effective wintertime ventilation for pullet houses requires prefabricated light trapped inlet vent boxes connected to vent machines and operated by static pressure. These are indispensable and are being installed in most new houses. Hand-made wooden boxes are much more diffucult to operate and to pull air through than the modern prefabricated light trapped vent boxes.

Virtually all pullet houses in the broiler belt of the United States are going to tunnel ventilation.